The article isn't very precise, but my understanding was that the run some kind of machine learning based on past data. Adding in the more recent data changed the predictions dramatically.
So it's not an issue of versioning (I assume they could reproduce the old results using the old data).
It's not machine learning, it's a physical model. Computers solve a big differential equation that takes in all of the physical things we know about the Earth's climate system and runs them forward in time. The increase in thermal predictions are due to changes in the cloud and aerosol models which were made due to an improved understanding of the physics involved.
The line can be a bit blurry, because they are actually running inverse problems with the PDEs to fit the data. This needs regularization just like statistical ML models. Usually this amounts to solving an iterated least square problem, just like logistic regression. Bayesian methods are becoming more popular, though.
Yes, that's right. The issue is that systems like these have a lot of free parameters that have to be estimated from the data. This is basically because you have to make assumptions if you don't want to simulate Earth's systems down to the subatomic level. The inferred values of these parameters are usually very important as well for interpretation.
All PDEs are solved numerically by discretizing them into linear or nonlinear systems. If it's convex enough, Tikhonov regularization is often used.
Linear PDEs, where the solution depends only linearly on its derivatives, can be discretized into matrices. This gives a system like A m = d, where A is the discretized PDE, m is the "model" or parameter values, and d is the data. This is usually over or under-determined from the data, so it has to be solved by least squares. Since the resulting system is usually almost singular, regularization is applied, usually by penalizing the L2 norm of the model:
min || A m -d || + r ||m||^2
If it's nonlinear but convex enough, one can just solve it by fixed point iteration, with the above linear equation being solved at every step (Newton's method often doesn't work well). If it's too nonconvex, then MCMC or other Bayesian methods are better, since a single solution is useless if the parameter values could plausibly around widely separated minima.
They technically use the term constitutive model development. The math is similar to machine learning.
Typically we know the basics of the physics, i.e. conservation of energy, momentum and angular momentum which set up the equations. But there a number of constitutive laws which relate parameters between these are "machine learned" but in generally, they are typically linear relations.
Well, politicians aren't doing anything anyway, whether the models predict catastrophe or CATASTROPHE. Already according to the 3° sensitivity predictions we would need an effort that rivals WW2 to stay below 1.5°. Yet major countries are led by climate denialists.
Can you even imagine how a Total War economy/society based on transitioning to greener energies, cutting emissions and pollutants, and working on improvements to housing and urban planning would end up looking?
Like ignoring the whole climate change thing for a moment (though we absolutely should not do that), just the quality of life improvements to our health and well being this kind of mobilization would bring would be astonishing.
The wartime World War Two economy we learn about in school was only made possible because of two factors:
1) A massive surge in federal government spending, financed by borrowing from public markets (incl. war bonds), to buy the materiel needed to fight a war on two fronts (in Europe against Germany and in the Pacific against Japan). Such spending caused the public debt as a share of GDP to surge to its highest historical level ever, from about 40% at the start of the war to 100% at its peak, as you can see on this graph: https://upload.wikimedia.org/wikipedia/commons/a/a7/US_Debt_... . Today, without such a total war effort, we are running trillion dollar deficits. To put it as shortly and bluntly as I could, trying the same thing today would bankrupt the government. Our debt levels are far higher than they were then, in relative terms, and increasing by over a trillion every year. We would be looking at 2 or 3 trillion dollar deficits. Deficits of that magnitude might shake investors' confidence in the U.S.'s ability to service its debt.
2) The United States was coming out of the Great Depression, and the unemployed labor pool was in the double digits, as you can see on this graph: https://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Un... . In other words, there were a lot of unemployed people with nothing to do who could quickly be put to work to produce stuff for the war economy. This is not the case today. The economy is running at full employment. The large spare labor pool that existed then doesn't exist today.
America has a large shadow labor force. People who do not regularly apply to work are not counted as officially “unemployed.” Have to take this into account.
Total wars are not known to increase the quality of life. If a transition to a green economy guaranteed such massive economic gains (and no pains) don't you think that politicians of all colours would scramble to implement it? The first step to solving issues is to acknowledge all the difficulties that lie ahead: otherwise you end up in a delusional state in which solutions are obvious and easy and the only reason they're not adopted is that everyone else is evil.
The other sad conclusion to derive from this is that the "improvements to urban planning" bit is largely not happening, despite generally broad bipartisan support.
It signals to me that people like complaining about things, but do not participate in politics in any productive fashion. Right now it's just team sports, and most people can not name the candidate they are voting for, outside of the presidential election, until they read it off the ballot.
It may also be that people like the idea of 'improvements in urban planning' when they are intangible, but if those changes involved limiting their land use or bulldozing their inefficient homes and neighborhoods they balk; they may also not like moving those planning decisions from their local communities to some bureaucracy outside of their direct engagement.
Don't need to bulldoze much of anything to do something though. The inefficiency of buildings is a tiny part of the problem, especially in temperate climates; more mixed use zoning, and the relaxing of single family dwelling zoning, will have a dramatic impact on excess travel.
Transport accounts for basically a third of U.S. energy use, though it has been hardly growing over the last few years, which is a good start.
The most efficient car, bus, or train, is the one that you didn't ride.
I think we agree. I meant inefficiency in building density not energy use. I was thinking about row houses in San Francisco and brownstones in New York City. Old short and inefficient buildings could be torn down and replaced with tall, dense, efficient structures; but people who own row houses, or rent apartments with high rents, or like the way their neighborhood is now don't seem to want this kind of transformation.
And over what time period would you finally offset the excess co2 introduced in the environment by tearing down and rebuilding existing buildings? They're already medium-density buildings, with considerable historical and urbanistic value. Seems a crazy idea to me.
> Total War economy/society
> quality of life improvements to our health and well being this kind of mobilization would bring would be astonishing.
The impact on quality of life and society would be "astonishing," but they won't be improvements. The Soviets and Chinese tried similar "mobilization[s]" for food production. The idea was to direct society's efforts to producing enough food for everybody. Tens of millions of people died of starvation as a result. It turns out that governments are bad at running economies.
I don't know why so many people think that the same mechanism (a command-and-control economy) will lead to a different result just because you change the goal from food or industrial production to climate change mitigation.
Thanks for the straw man. American WW2 mobilization didn't kill ten million people - that's not an intrinsic attribute of a country focusing on something.
Think also new deal / public works projects like the Hoover Dam (many died working on the Dam but not because it was a government mobilization project). Just the government spending a bunch of money on environmentally focused projects could happen and could be good.
It's not a straw man, and your examples are no more apt than Rayiner's.
America's WWII mobilization is really nothing like the Green New Deal. The total cost of the U.S. war effort is estimated at around $300 B (adjusted for 2009 dollars) [1]. The lowest realistic estimates for the cost of an effective Green New Deal are around double that amount every year, and lasting for decades [2].
It's true that WWII cost far more relative to GDP (over a third, versus 2% for the New Green Deal estimate above), but expressing the cost relative to GDP is not very useful in this context; in 1945 the U.S. was poised to enter a period of ten percent annual GDP growth at a time that military spending was plunging. The situation now is completely opposite; the U.S. will possibly never sustain greater than 2% GDP growth, and the Green New Deal proposes to pull money out of that for decades to come.
The character of WWII spending was also completely different. That money was largely spent on things that were pretty much guaranteed to help the war effort; materiel, industrial infrastructure, and troops. There was little risk of misallocation.
In contrast, the Green New Deal is fraught with misallocation risk. In that way, I suppose that a comparison to modern military spending is actually quite appropriate.
Well, what other experimental data is there? If these incidents are the only data points, then that's the natural extrapolation, even though it is only weakly supported.
As someone else pointed out, the New Deal, which gave us massive infrastructure projects that we still rely on and helped set the stage for postwar prosperity.
The impact of the New Deal on post-war prosperity is debatable, but I want to focus on two different points. First, the New Deal mobilization is small in comparison to what has been proposed in the context of the "Green New Deal." From 1930 to 1940, total government spending (at all levels), jumped from 12% to 18%. That's 6% of GDP, or about $1.17 trillion annually. It's unclear what folks who use the phrase "total war mobilization" mean. If you're talking about the Green New Deal's proposal of hitting 0 carbon emissions within a decade, that's not close to enough: https://www.factcheck.org/2019/03/how-much-will-the-green-ne...
> Pollin, however, strongly disagrees with the resolution’s aim of getting to net zero with just a decade of investment. “I think it’s completely unrealistic and it’s not worth costing out,” he said of the Green New Deal.
$1 trillion is the price tag of a much more conservative approach that puts a much longer timeline on carbon reduction:
> Edward Barbier, an economist at Colorado State University, agrees that a strict timeline isn’t realistic. He advocates jump-starting the transition by investing about 5 percent of GDP over five or so years. GDP was $20.5 trillion in 2018, according to the Bureau of Economic Analysis, so that’s a little over $1 trillion a year. “That would push us on a path to clean energy, and a path that permanently lowers carbon emissions,” he told us.
The second point I want to make is that we have much less headroom to do a "New Deal"-style project than we did in 1930. We are actually already far in excess of New Deal-era government involvement in the economy. (See my link above.) Today, government spending is at around 35% of GDP. We are in fact closer to the "total war mobilization" of World War II (where spending peaked at 45%) than to the New Deal era 18%.
This demonstrates nothing other to me that the complexity of Capitalist economies and their industries grows over time in such a way that requires further state intervention and support to undergird them. This is true across most of the developed world and in regimes like China and likely will only expand in the future. Especially if Capitalism is to possibly survive the destructive consequences of its externalities.
You’re referencing The Great Leap forward right? Because if so you’re completely ignoring the details in an attempt to use it to bolster your point. The reason tons of people died in The Great Leap Forward has nothing to do with food production per se. Rather, the Chinese government declared several animals to be pests and commanded everyone to eradicate them to protect the harvest. Among those animals were sparrows. Sparrows are minor agricultural pests, but they are fantastic at eating bugs. And so, having hunted sparrows nearly to extinction the Chinese were unpleasantly surprised when a huge plague of Locusts descended on their fields and ate nearly all of the harvest.
So the real lesson is not that command economies are bad but rather that unforeseen circumstances should be avoided. If they hadn’t killed the sparrows we would not now be hearing about how many died.
> If they hadn’t killed the sparrows we would not now be hearing about how many died.
The Four Pests Campaign is a great example of humans suffering the unintended consequences of their own stupidity and hubris. However the Great Famine had many proximal causes, and there is no evidence that simply sparing the sparrows could have prevented it.
Germany had a Total War economy in WW2. North Korea has one today. The Russian Revolution might not be considered 'Total War', but was single-minded in its focus similar to what you're suggesting. None of these economies worked out well for their citizens. Even the US economy/society during WW2 was more than victory gardens and war bonds; personal freedoms were limited, there were interment camps, forced enlistment, war profiteering, and propaganda (along with the hundreds of thousands of deaths).
My point is that Americans were willing to pay that price even though the actual threat of Nazi Germany was not even in the same ballpark as the threat posed by climate change. I'm also reasonably sure that the switch away from fossil fuels can be done without hundreds of thousands dead.
That's not how I imagine a total war. The point of "Total War" is that you start making every decision necessary to achieve your goal, that you weren't willing to make under a democratic process.
If we go to total war to prevent climate change, that means things like:
* Shutting down power and fuel supplies to poor countries that can't afford current solar or wind power
* Military conquest of uncooperative countries
* Bombing coal mines to shut them down
* Bombing oil fields so nobody can get the oil
* Slaughtering foreign civilians to reduce their carbon emissions
When I think of a "total war" caused by an emergency response to global warming, those are the sort of consequences I imagine. Let's hope we don't get to "total war".
It's because the predominate feeling of those in power is this issue is overpopulation. And yes a population reduction the type WWII provided would be in the 'right direction'. That this is all 'carrying capacity' and they know how to deal with that. Just need more room to live.
Steve Bannon and Trump are fans,
"The authors envision a return to a more traditional, conservative social order as one outcome of a crisis. They also see the possibility of retribution and punishment for those who resist or refuse to comply with the new expectations for conformity. Mr. Trump’s “with us or against us” attitude raises questions about what kind of leader he would be in such a crisis — and what kind of loyalty his administration might demand." https://www.nytimes.com/2017/04/08/us/politics/bannon-fourth...
Major countries are led by popular demands. Minor countries as well.
Vast overuse of energy resources is a pattern intertwined with modern life, from housing to transportation to food to recreation. The people demand having a vehicle with more than 100hp at their whim. Now picture a herd of 100 horses for every person on Earth. It is political suicide to propose cutting down to ecological sustainable levels of 1 horse per person. That's before we take in account the population explosion of 5-10-20x compared to pre-industrial levels. Not sure where you even begin implementing policies to reduce the population levels to ecological sustainable levels.
As a species, we are simply incapable to comprehend that the way out of poverty is intelligent frugality. Instead, we attempt to brute force our way. The effort needed to fall back into an ecological sustainable band far surpasses WW2, and no one wants to hear about the actual costs. Nothing will change until mother Nature will do the change for us. The hard way.
We already know how to reduce population - education for women and access to contraception. Birth rates have slowed so much in some parts of the world that it is, apparently, worrying for their economic stability.
We humans have developed one fairly good approach to problem solving by focusing on localized concerns and self-interest. For many problems, this seems to work fairly well with a few negative yet manageable side-effects.
In my opinion, these approaches completely fail at solving large issues that require large orchestrated efforts that require things at state, nation, and even world scale and longer timescales than an individual or their kids.
We haven't really developed a 'hammer' for those sort of problems and that hammer keeps competing with our 'saw' we use on the other problems whose proponents want to only use their 'saw' for every problem they see, ignoring its shortcomings.
Yes, I think it is pretty clear that this social structure is the cause and at this point the only solution. Why the only solution? Generally I view the prevention of a strong global government to be a conservative issue and for better or for worse that isn't likely to happen (peacefully). The construction of such a government would speed up solving this issue but then we'd be left with another power hungry government to reign in.
Certainly high ROI ones (say not building new coal power plants), but definitely not the lower ROI interventions.
Nor is cost net negative if you use high discount rates and try lower co2 targets (e.g. 3 degrees warming by 2100 is much more likely to have positive ROI than say holding 2 degrees). Huge controversy around protecting against lower probability, highly destructive scenarios. Point is there's lots of controversy here.
> Already according to the 3° sensitivity predictions we would need an effort that rivals WW2 to stay below 1.5°.
Comparisons to a war are overly dramatic because it puts the destruction on the opposite side of the effort. If you're in a war and two countries spend a trillion dollars fighting the war, those resources go to causing trillions of dollars of damage to the other country -- most of the cost of the war is getting bombed, not making bombs. With climate change it's the opposite -- the more we do against it, the less damage there is overall. On top of that, most of the "costs" are just replacing other costs -- you have to spend money building solar panels, but then you don't have to spend money doing oil exploration or mining coal, which offsets most to all of the cost.
On top of that, wars are characteristically fought by governments with all the bureaucratic inefficiency that implies, whereas the single biggest thing we could do against climate change is to accurately price carbon and then let the market find the most efficient way to optimize it out.
Obviously that doesn't get us out of actually doing it, but the biggest problem isn't that it's actually that hard from an economic perspective, it's that it's hard from a political perspective because the oil industry has a trillion dollar interest in not ceasing to exist.
> While it is true that we estimated damages as high as 10% of GDP annually at the end of the century for warming of 15°F above pre-industrial levels, the odds of a temperature change that would drive damages of this magnitude are slim. In fact, they are less than 1-in-100 by our original calculation. Under a scenario of continued growth in global emissions, 9-out-of-10 global change temperature projections fall approximately in the range of 4°F to 11°F by 2100. The median change is closer to 6°F. We deliberately incorporate tail risks in our research, not just “most likely” outcomes, because consideration of tail risks is crucial to sound risk management.
> In other words, if global GDP doubles or halves by 2100, the results suggest real GDP per capita would still be 7.22% below where it would be otherwise.
For most of the world, an RCP8.5 scenario is equivalent to knocking out 3-4 years of GDP growth. Bad, but not catastrophic, and probably less bad than the impact of "WWII-style mobilization" and shifting the economy into command-and-control mode.
Pointing at GDP over and over again is at a best a fuzzy indicator of overall well-being, especially in the developed world where inequality has unmoored it from improvement in material standards for many people. Amazon stock prices skyrocketing tells you little about the health or well-being of their workforce.
GDP is the number we have. It's not perfect, but it's better than trying to assess the costs without reference to numbers. More significantly, GDP per capita gives a strong measure of the country's capacity to provide for well being, including through redistribution. The specific redistributive policies we adopt or not are mostly orthogonal to climate change.
> Our localized approach to studying the relationship between climate and society reveals that the burden is spread unevenly. In many counties, GDP decline could total more than 10% by 2100, and in the worst-hit county, Florida's Union County, losses could near 28% for a likely warming scenario under continued emissions growth (the 7°F median change, not the extreme 15°F change highlighted in press coverage). The combined tally almost certainly understates the extent of the damages, because the worst effects are concentrated in places where incomes are lowest. Tumbling incomes in poor counties have a correspondingly small impact on nationwide GDP, meaning the economic burden of climate change is reduced because it falls on those with low incomes.
> If the burden is spread evenly, 1% or 2% of national GDP might seem manageable, but we will not all be equal in the face of climate change. Across the United States, there will be winners and losers. What is lost in all of this noise is the sad fact that even those smaller numbers are too high a cost. They come from a subset of outcomes that are well-measured. As ever in this debate, it is important that we look beyond the headlines, beyond the averages, and examine the people at the heart of the issue. Look at the mass of evidence that points to people who will actually be negatively affected by climate change. They are not abstract people not-yet-born and in some far-off land. They are your neighbors. They are your friends. They are you. Combining local climate projections with historical observations yields a personalized, evidence-based outlook of future risk. Our ongoing research is mapping out these local impacts across the globe.
It's only catastrophic if we don't respond appropriately to mitigating the impact in hard-hit areas, and even then only to a relatively small number of people. Retooling our system to perform that mitigation is a much more limited task than the "total war economy" people are talking about to address climate change.
Why is a 1.5° maximum a target that should be aimed for? William Nordhaus says a 3.5° maximum is the optimal target. His models show that a 3.5° maximum would result in a net benefit of 30 trillion whereas a 2.5° maximum would be a detriment of 50 trillion[1]. That is to say the reduction in damage would be far less than the cost of implementing such a policy. The cost for a 1.5° maximum target would be even more severe.
[1]W. Nordhaus, “Projections and Uncertainties about Climate Change in an Era of Minimal Climate Policies,” American Economic Journal: Economic Policy, vol. 10, no. 3, pp. 333–360, Aug. 2018, doi: 10.1257/pol.20170046.
edit: This comment is currently sitting at -2. If you think a 1.5° target is optimal, you should explain why you think so rather than just down voting this post. The paper I linked to is by William Nordhaus who won the Nobel Prize for economics in 2018 for his work related to the economics of climate change.
"we would need an effort that rivals WW2" Exactly and from what I remember WW2 had around 75 million casualties. Which is an unfortunate and grim prediction on what it's going to take to get any real action from politicians.
I’ve read a few times that clouds are a big problem for climate modelers as they are far more complex in their implications for the climate than my grade school planet heats > evaporation > cloud forms > rain falls understanding of them suggests.
Animals have immune systems too. It’s not a phenomenon unique to humans, as Anthropomorphism would suggest.
> they don’t like it
Who? HNers? I don’t care. I think it more that people don’t like seeing themselves as the virus or cancer, when we could easily change our behavior and we wouldn’t be.
The title seems like clickbait, and the last part of the article does explain that the scientists actually know that new cloud models are mostly responsible for the change.
The big question is then of course whether the new cloud model is wrong and the temperature increase therefore as well, or whether the new cloud model is more accurate than previous ones and the temperature increase is a real effect.
I found another article that looks at this in a bit more detail:
Or a third, frustrating possibility—the new cloud model is more accurate, but some other inaccuracy in the model used to be balanced out by the inaccurate cloud model.
Or that there are multiple inaccuracies in the model which interact, so finding and correcting each one makes progress but still doesn't improve the model overall.
Having built some models to simulate very basic things myself, I've seen first-hand how the slightest deviation of the model from reality can completely invalidate the entire output of the model.
For this reason, I'm skeptical of models that try to simulate very complex systems with a lot of variables and feedback loops.
Models that have a large number of variables are particularly difficult to get right because different tiny mistakes in various parts of the model can compound and yield completely arbitrary and contradictory results. Approximating the reality in software is almost impossible.
It's not impossible. Listen to this podcast, it's a discussion about weather forecasting models with the scientists that create them. They discuss model verification for weather models and they touch how this also applies to climate modelling.
http://omegataupodcast.net/326-weather-forecasting-at-the-ec...
Cloud modelling is only part of it - advances in computing have allowed the reduction of cell size, allowing more detailed and therefore hopefully more accurate physical simulations.
> advances in computing have allowed the reduction of cell size, allowing more detailed and therefore hopefully more accurate physical simulations.
'Hopefully' is doing a lot of work there. In modeling a highly dimensional dynamic system it's not obvious that a smaller cell size will lead to more accurate predictions.
I guess that depends on the nature of the models. If they actually capture the inherent chaos of the system they claim to model, then minor tweaks will have wildly unpredictable side effects.
Not to diverge, but I'd be extremely wary of editorial bias/spin from this particular publication until November or so.. which is not to say that the topic itself is suspect - as you point out, the big question is if the updated model is actually worse than previous models or if it is better
"In all, as many as a fifth of new results published in the last year have come in with anomalously high climate sensitivity." The article suggests that a consensus may well form around the new, higher estimates. So, quite possibly.
"You are in private mode. Subscribe to continue reading." Ok, that's one more I will not open anymore; seems Bloomberg started using similar "privacy mode" detection as NYT.
I use two browsers for this scenario both on iPhone and desktop. The first browser is my regular one (take your pick) and the second one is Brave with scripts Disabled (one click option in settings). I use Brave when going to sites like this.
Disabling scripts generally doesn't break these types of sites but it does stop them from detecting whatever it is they are trying to detect.
I don't see how you brought socialism into any of this.
Ironically, socialism is being sold as a solution that you yourself make very clear. That, the pace of scientific progress is really fast ,and automation is going to make a lot of jobs obsolete.
Socialism (in the nordic sense, ie. capitalism with social welfare) is being proposed as a solution to rising inequality and unregulated for-profit forces in the free market of industries where the consumer has no choice. (medicine, education)
I mostly somewhat agree with you but unless you find a more appealing package for your arguments, you're just going to exacerbate the bifurcation on issues like this, and definitely not convince or enlighten anyone.
I am not a climate change denier by a long shot, but stories like these give a ding to the credibility of climate scientists.
> "So we can't throw them out yet."
This might be an elementary view of science, but I think there is a danger here that while everyone is making their models, if anyone is an outlier they go and tweak their model to match the patterns of others: 'Klaus Wyser’s group "switched off" some of the new cloud and aerosol settings in their model, he said, and that sent climate sensitivity back down to previous levels'. That seems to me a questionable reason to "switch off" part of the model - you should create the most accurate simulation possible and trust the output, not tweak the inputs to match literature data.
Typically it's not obvious what to switch on and off for "accuracy".
If your model produces wildly different results from previous models, either you hit on some really big discovery or you made a mistake. An ethical scientist will try to rule out the latter possibility before accepting the former.
It goes deeper than that. If you can tweak your new model to correspond to an older one for which you have results available, you must run tests in which you apply these tweaks and verify that you get the same results. If you get different results, one of the models simply isn't doing what you think it's doing and you need to understand that. And in the vast majority of cases, it's likely a mistake in a model, not any kind of new science.
One pretty general debugging/analysis strategy for a complex model is to deactivate it piece by piece until you get it to a point where it should reproduce a result that you can verify by other, independent means. E.g. tweak the parameters of the model so that reproduces a result that is known analytically. For instance, whenever it is possible in a model, a good sanity check is to set parameters that must lead to e.g. a perfect conservation of certain quantities.
Tweaking the inputs would help one to identify what factor is causing the difference, which allows you to focus on that. It doesn’t mean you permanently leave it out.
And it does not make a credibility issue. This is how science works — it is a process that strives to be as accurate as possible, not come up with a static answer and stick to it (that’s what religion does).
The ability for science to change and adapt is what makes it so strong. That is the message that needs to always be driven when discussing science; not throwing hands in the air and saying “why do these scientists keep changing their answers? They obviously don’t know what they’re doing”
These are valid points, and it is important to figure out what changes in the model is causing such a dramatic change and scrutinize it more.
> The ability for science to change and adapt is what makes it so strong
To me this article is them _resisting_ change, looking for a reason NOT to accept it, because it goes against what they previously said. Maybe this is all to early, and in a year or so we will be seeing 4 or 4.5 degree predictions, but this article describes them trying to change their inputs to match previous answers, not getting new answers.
If your model suddenly changes its predictions, you need to make 100% sure you know why and that is valid.
Just imagine they would go public with this "Scientists found climate change is worse than previously thought with updated model" and then weeks later find an error in the changes made to the model "Scientists made mistakes, climate change less severe than previously thought".
What do you think would hurt their credibility more?
Well this is the problem. People are reticient to make public a private finding that is different, because it is probably wrong and they'll probably lose credibility. But if everyone is doing that...
They are not reticent to make it public, they are publishing papers and are asking for peer review. There is a public newspaper article about it with quotes of the involved scientists. They couldn't be any more transparent about this.
They are not throwing away their findings and they are not burying it. They are working to valdiate/invaldiate them, because they are scientists.
Again, that's the way that science tends to operate - a la Kuhn and his Structure of Scientific Revolutions. You have some novel research that seems to contradict well-established consenus. It comes under close scrutiny, because science tends to be conservative. If after giving it a good kicking, its clear that the old consensus is wrong, science takes the wrecking ball to it. But it prefers not to get the wrecking ball out of it can help it.
> You have some novel research that seems to contradict well-established consenus. It comes under close scrutiny, because science tends to be conservative.
Indeed, even people we nowadays consider brilliant minds of their time, encountered plenty of resistance [0] during these very same times because their proposed ideas just seemed too outrageous.
It certainly does hurt the credibility of people saying we need drastic changes now based upon the models. If the answer might change next year, then making a drastic change based upon the current projections seems foolhardy.
The answer is going to change every year, with new inputs from the prior year. That is how prediction models work. Using your logic would lead to never making any changes, which I don't think will really help.
They say we need drastic changes based on the best evidence we have along with given the likely outcomes if change isn't introduced.
What you're saying is that you have established a prior that undermines all further evidence presented to you, because it has changed substantially in the past. However, that seems irrational to me.
Too much of it is, as water in your lungs, or air in your beer: having too much of it will make your greenhouse too hot, the one you live in and cannot leave.
This isn’t really a helpful reply, because of course it’s not a question of magically reducing pollution.
There are two basic modes of reducing pollution. Technological advancement, and conservation.
In the case of technological advancement, you get less pollution per unit of output as the same or lower cost. As long as capital is fairly cheap, these advances tend to propagate quickly through a competitive market.
In the case of conservation, it’s more a question of which groups of people should conserve (i.e. suffer) for this outcome, and by how much.
Why do governments fail to take advantage of this opportunity to inject money into their economy? Didn't Trump promise to bring the manufacturing jobs back? How is he going to achieve that if he's not going to rebuild the current power infrastructure or discourages companies from investing into the lucrative EV market?
I'm seriously wondering why there is any reason to oppose technological progress at all. What can they possibly gain by sticking to the old technology? Who's going to benefit from something so short sighted?
FUD. The statement that we need drastic changes is not dependent on the details of the projection and is not based on it. Further, climate models have correctly predicted the heating we have already caused.
We have known the rough level of the climate sensitivity (delta T per doubling CO2) in the current macro state for decades. We have observed it. This science is incredibly settled. We don't know where the tipping elements are and we don't know how the impacts will be distributed.
Questioning the credibility of people calling for action might look like you are being the circumspect and rational one, asking for action proportionate to the evidence. In reality you are endorsing an ignorant position that ignores the evidence we have. If this is not wilful ignorance then please read up on this. The IPCC report summary is a good spot to start. Sceptical Science also often provides good writeups: https://skepticalscience.com/climate-sensitivity.htm
The fundamental physics that drive the sensitivity are straightforward. Energy balance and water vapour. That gets you a ballpark figure that is confirmed by the last 100 years of emissions.
Individuals, corporations, and the politicians who set policy all operate on imperfect knowledge in many many domains as a routine matter of course.
It is a denier talking point to claim that we just don't know enough, or that the models are always being tweaked and we should just wait until scientists have "the final answer" before doing anything.
Hey, let's stop giving NOAA weather forecasts because they aren't 100% accurate. Let's close down the stock market until everyone can decide what the values should be. Let's disband the military because not all military leaders have the same opinion.
If we are mature enough to recognize that imperfect but credible models are worth acting on in other domains, why do we hold climate change to impossible standards?
Sadly no, the hypotheses that are now being shown to have been too optimistic were the ones that implied drastic changes. The updated models are telling us something else, you'll figure it out, and/or it will figure you out.
Try thinking from a basic Risk Analysis point of view. If climate scientists are wrong and we do something we will invest heavily in infrastructure and efficiency, reduce our environmental impact, and reduce air pollution for our children. If they are right and we do nothing then the 9 to 11 billion of us still living on Earth will be crammed up against the North and South poles while sea level rise claims many small nations. We will run low on arable land, many of our animal and plant species will die, and the planet our children inherit will be a dirty hellscape that’s too hot to live on.
Given that, how could you possibly advocate for doing nothing?
But it should make the scientists more circumspect about public policy recommendations. They're not making evidence-based policy, if yesterday's models are evidence and today's models are not.
> This is how science works — it is a process that strives to be as accurate as possible, not come up with a static answer and stick to it (that’s what religion does).
That's fine. Many public policy advocates throw around the term 'settled science'. But based on what you said, is there such a thing?
But it should make the scientists more circumspect about public policy recommendations.
From the article:
Climate models have been doing a fine job projecting warming for a long time. A recent study compared models as old as 1970 with observations made in the decades since. Some models warmed up too much, and some too little, but 14 of 17 past projections turned out to be consistent with the measured path of global average temperatures.
Scientists can not give definite answers in such complex systems, but it is the closest we can get in extrapolating the trajectory that we are on and computing what the effect of various measures is.
> That's fine. Many public policy advocates throw around the term 'settled science'. But based on what you said, is there such a thing?
Yes, there is. Just because there is no absolute certainty, doesn't mean it's all just baseless speculation. Just because, as a matter of scientific methodology, atomic theory is not absolutely certain (i.e., we could hypothetically find evidence that contradicts the model), doesn't mean someone just made it up and it has no predictive power.
I think you're missing the point. From how I read the parent comment, the problem they see is how scientists are using the data available to them. When you make a hypothesis, you are supposed to validate or invalidate it based on its predictions - not change the predictions to fit the evidence.
If you change your model (hypothesis) to fit the facts, your model is merely descriptive of the evidence that is already available, and useless for prediction - as proven by the act of changing the model. That's how science works.
Uh, you realise this article is about work in progress, right?
If you want to cast it in the rigid hypothesis testing language (not a very good description of the actual practice), the description is this:
A physically motivated modification to existing tools lead to unexpected results that are not understood yet. As part of figuring out the cause of the new result they are running a series of smaller experiments to test various hypothesis of what aspects of the modifications matters most for the new results.
In effect, objecting to the practice of turning things off and on again is to object to the very notion of doing experiments, which is not very scientific.
I don't know how you could have reached that malicious interpretation of why that part was switched off. To go and impugn all of climate science in the basis of a misinterpretation of motivations would indicate that you have internalized the denialists claims and look to seek to justify them.
To point out just how wrong your misinterpretation is, the very next sentence has the "why":
> A new research paper co-authored by Zelinka from the Lawrence Livermore National Lab likewise pointed to the role of virtual clouds in determining the results.
The key phrase being "role of virtual clouds." The motivation wasn't to slavishly reproduce results from the literature, and to even suspect that it completely outside the bounds of reasoned discourse. It comes across as if you are trying your hardest to find something to nitpick, some small phrase that you can misinterpret in order to raise doubts in those who aren't paying close attention.
This is exactly how denialists and propagandists behave.
I'd propose that has more to do with the headlines than any of the actual science. Model tweaking is exactly how a lot of this works - models are supposed to reflect reality, so part of how we explore them is to find out what models fit past (and predict current/future) reality. This is both intuitive, and based on theoretically sound inference (see Approximate Bayesian Computing for an exploration of the connection between simulation and formal inference).
This part of climate "science" always makes me put on my Popper hat. The social aspect of being the outlier (grants dry up, career goes away) makes me skeptical of the IPCC reports, just not in the usual direction. I fear reality could be much worse.
I can't ding the climate scientists too much, though... I'm not sure there's a better way to study this stuff.
I don't think I implied they did. I'm only saying that humans are social creatures and that scientists are susceptible to peer pressure (even in "hard" sciences with lots of possibility for experiment). I imply no maliciousness, but am trying to voice my fear of the impossibility of knowing whether or not the consensus warming scenario is a "reversion to the social mean", that is, we just have to wait and see if warming is worse that expected.
But I'm only a bit surprised this would be such a controversial opinion here.
This idea, along with the null hypothesis, are simply not honored by this part of the scientific community. Climategate proved this ten years ago. It's a doomsday cult and they'll stick you with the "D" word if you don't narrative-fit. Check out Ned Nikolov's work for a better alternate theory.
That's the main problem I have with climate science. They don't really have the luxury of proving by experimentation, and I have seen enough perfectly good backtestings in my industry (finance) that go wildely off as soon as they go live, that I have a fundamental mistrust of backtesting as a way to calibrate a predictive model.
Especially because they seem to test it by making it predict history, but we don't have anywhere near the same amount of historical data. So what are you testing, really? Just that it accurately finds average temps?
Climate models as far back as the 1970s have predicted the temperature changes in the time from then to now -- those are not predictions that are coming from hindsight, but rather predictions where their effects were observed over the last 50 years.
From the article: "A recent study compared models as old as 1970 with observations made in the decades since. Some models warmed up too much, and some too little, but 14 of 17 past projections turned out to be consistent with the measured path of global average temperatures."
So we actually did an experimental test of the predictions made in 1970, and those predictions turned out to be largely correct.
We should probably halt this experiment on ethical grounds.
Sadly the political activists have hijacked the normal scientific process. And this allowed some pseudoscience (with alarming predictions or alarming observations) to mix in too.
In some science news I read that the Arctic Ice-sheet is growing back, and that Envisat showed that the oceans were not rising. So very likely the climate is more complex than some alarmed scientists thought.
The reason clouds are starting to be simulated now where they weren't before is probably because we have only recently had the computing power available to do this at the level of detail required. Switching the 'clouds' feature on and off is part of the model verification process. Listen to this podcast[0], it's a in depth technical discussion about weather forecasting models with the actual scientists that create them. They discuss model verification for weather models and they touch on how this also applies to climate modelling.
Does anyone know if this is actually true? I was under the impression that climate models have been mostly overshooting reality over the past 40 years
> One question modeling can help answer is called “climate sensitivity,” an estimate of how much warmer the planet will be once it has adjusted to atmospheric CO₂ at double the pre-industrial level. (At current rates, CO₂ could reach a doubling point in the last decades of this century.) This is the old, reliable number that’s come out to 3°C for 40 years. It was as close as anything gets to certainty.
Pardon the pedantry, but "-the- models have done a great job of predicting reality" seems like a bit of an overly strong statement. The link you give and the original article seem to be comparing a completely different set of models, and the main article even says there are "dozens still left to report....".
Perhaps. I'm just pointing out that using ambiguous terms like "the models" is problematic, in that you and the original article both refer to "the models", but you are dealing with entirely separate sets of models.
Perhaps literally all historic climate models have been accurate, I've read extremely enthusiastically received articles suggesting as much.
If you are like me, you hate reading articles like this. You know there is a problem but you feel like you can't do anything about it. You recycle, you turn off lights, you have a programmable thermostat but you know it's a drop in the ocean.
I finally decided to do something about it last fall. I researched and have committed to purchasing green power. Every month I purchase 850 kWh for $22 from Bullfrog Power (a Canadian company, I have no affiliation). It's much more reasonable than I thought. I still conserve as much as I can but $22/month allows me to feel like I am doing something. If in 40 years, my kids ask me what I did to prevent climate change, I feel like I'll have an answer I'll be proud of.
That's awesome and I'm right there with you on wanting to do more.
Have you considered your next step, and do you have any suggestions? Purchasing green power is such a minor sacrifice for my household, I'm still looking for something more.
My next steps will be writing to my government representatives. I live in Alberta and we just elected a right wing party that scrapped our carbon tax (although we now have a federal carbon tax).
> If in 40 years, my kids ask me what I did to prevent climate change, I feel like I'll have an answer I'll be proud of.
Doesn't it kind of feel like this is the equivalent of a kid in the 70's asking why their parents didn't stop World War 2? We absolutely need to be as vocal as possible, but as individuals, outside of trying to get people with power to affect the change we need, I don't know what we can expect to accomplish. You just can't do enough diet modifications, carbon footprint reduction, or recycling to have it matter on a global scale.
Why would we have wanted to stop WW2? WW2 was an objectively good war for the Allies to fight (not that the Allies had a choice, as it only takes 1 side to start a war).
I feel like you're missing my point, but I'll concede it may have been a bad example, even though I find it hard to argue that it was good that all those people died, which would be a child's understanding of the event.
>You just can't do enough diet modifications, carbon footprint reduction, or recycling to have it matter on a global scale.
I used to think like that. I used to think "There's nothing I can do, why do anything." Then I had kids and I realized that I need to be able to tell them I did something. Our world might be a wasteland of burnt forests and flooded cities, but at least I will be able to look my children in the eye and say "I tried."
There is a problem and you can't do anything about it. We are way past the point where individual action is going to cut it. You have to vote. No other action is going to have a meaningful impact and you shouldn't pretend otherwise because it makes you feel better about yourself.
Not being a Chinese citizen, there's very little I can do there (AFAIK there's not very much I could do if I was either). I certainly will vote for any politician that promises to put pressure on China to change their policies.
China is actually also doing a lot pro-climate. Also, reading this as a German: I think the U. S. can do a lot first, before pointing their finger to China. Same for Germany btw., because we have similar discussions here as well like "why should we do anything? The US and China are the culprits".
You can follow this logic all the way down to an individual level.
If China doesn't do anyting, the US doesn't have to do anything either. If the US doesn't do anything, Germany doesn't have to do anything either. If not Germany, then not Munich. If not Munich, then not our little town. If not our neighbor, then me neither.
Everybody and every country should do whatever they can. Will it be enough? Probably not. But you gotta start where you actually have some control.
You're right that individual action isn't enough. But individual action does also have an impact. Commuter cars and SUVs (not airplanes, not shipping trucks) are the largest single source of carbon emissions in the US[1], accounting for about 15% of all US carbon emissions[2]. If just 1 in 10 commuters switched to taking public transit instead of driving, that alone would drop US emissions by 1.5%. If public transit became the default method for most transportation, we could realistically lop off 7-10% of US emissions. These are individual choices. It's true local and federal governments could do more to encourage using public transit, but most of that action would be driven by increased demand, which comes from individuals.
Don't fall into the trap that there's no reason to change your own habits because you think individual action doesn't matter. It does. But you're also right that it isn't enough.
[1] US EPA, 2017, "The transportation sector generates the largest share of greenhouse gas emissions. ... The largest sources of transportation-related greenhouse gas emissions include passenger cars and light-duty trucks, including sport utility vehicles, pickup trucks, and minivans. These sources account for over half of the emissions from the transportation sector." https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...
[2] Same source, 29% of emissions from Transportation; more than half that from commuter cars.
> If public transit became the default method for most transportation, we could realistically lop off 7-10% of US emissions.
I honestly struggle to understand this statement in the context of discussing individual action. Making public transit a reasonable option for most personal transportation in the US would be a public works project on the scale of the New Deal.
Perhaps more importantly, cutting US emissions by 10% is very nearly inconsequential unless it is part of a coordinated effort that is driving global emissions down by significantly more than 10%.
> Making public transit a reasonable option for most personal transportation in the US would be a public works project on the scale of the New Deal.
I don't agree. Most large-ish cities already have quite good public transportation networks, but outside of a couple special places like NYC, Chicago, and maybe SF, they're not the default option. If the demand is there, adding more bus routes and increasing frequency is trivial. Adding more rail and subway lines is definitely a major task, but we spend more on garbage like the TSA and the F-35 than we do on increasing public transit options; it's hardly a task on the order of the New Deal.
My overall point is individual action is a major factor in transit emissions, which is a major source of carbon, and thus individual action does have an impact on our climate change future. The fact that individual action alone isn't enough to fix the problem isn't an excuse for individuals to avoid making choices to lower their emissions.
> Perhaps more importantly, cutting US emissions by 10% is very nearly inconsequential unless it is part of a coordinated effort that is driving global emissions down by significantly more than 10%.
I don't agree at all that decreasing US emissions by 10% is inconsequential[1], but yes, of course, it is not enough. I already agreed with you that individual action is not enough. But it is significant. I'm trying to back up that assertion with numbers.
You also shouldn't pretend that voting is going to solve the problem because it makes you feel better about yourself. I agree that recycling a single aluminum can isn't going to make a big difference. But it could very well make a bigger difference than a single vote.
I am like you. And you and me both will be on the wrong side of history anyway, simply because we have children. It's the singles that are doing more for climate change than all those people with kids combined.
Not to rain on your parade, but programs like this from big power companies are essentially meant to allow customers to feel good while simultaneously not going through the work and cost of switching completely to renewable power.
That's because the power companies want to keep people from developing competition to them... if enough individuals install solar plants with battery storage, eventually they power company simply won't be needed any more, which is what they're trying to avoid.
By selling "green" feel good power, they quiet the impulse that people like you get to make changes that would impact their business.
It's still good that you choose to purchase green power over e.g. coal fired power, but it's also the power companies you're keeping in business that are causing a lot of climate change, and who have contributed to it all along.
The idea is that a CO2 tax will never be implemented. Instead of doing nothing the best thing you could possibly do is to self impose a CO2 tax on yourself. If politicians finally decide to implement a CO2 tax you've already prepared yourself and won't see a significant increase.
The problem of this "easy" method is that it does not scale: if everyone was doing it there would be much more problems to manage: renewables are not continous (storage needed), we do not have near enough capacity yet, the grid may not be designed for decentralized production, etc.
edit: also it is very rare to have the externalities included into the sum of CO2 emissions (dams need cement, wind turbines need steel, solar panel need mining, we need to transport these components, etc. -> all of that is probably not currently powered by CO2 neutral energy).
Is there a typo somewhere? I run multiple computers at home 24/7 and I'm using ~2500 kWh a year. Also, 850 kWh for $22 sounds crazy cheap, I pay ~100€ per 200kWh (including the rented meter, but more importantly, taxes).
Sorry I should have said, "every month I purchase offsets equating to 850kWh for $22". This is in addition to my regular electricity bill (I pay about $0.07/kWh). Bullfrog Power isn't my supplier, they are a company investing in green energy projects.
I’m a climate change skeptic almost entirely because I don’t trust models. I believe there are too many dynamic things happening in the world for anyone to be able to predict accurately say the next 100 years (solar, earthquakes, volcanoes etc). One way to make me a believer though is an experiment: if I were to give you a 100 year stretch of history and you were able to accurately predict with the models what exactly happened in those 100 years.
The article talks about it a little bit about how the models are used to predict the 19th century to see if they are correct. But the models use the last 100 years as input so of course it will give you accurate output. But the real challenge of the models would be to accurately predict things that are not part of the inputs into the model. I don’t believe that these models can do this and are thus an exercise in straight extrapolation based on very complex and interconnected inputs.
That's not what climate is about. Also, it depends on location, in many places it was colder in 2019 than in 2018. If you're talking about some calculated "global" temperature, it doesn't exist in a valid form.
It is not possible if there aren't valid temperature measurements available for all points throughout the measured period of time, so that many temperatures are "interpolated", estimated etc.
Except that we do have a massive number of recorded temperatures across a massive number of locations in the last 100 years. Climate models, some dating back to the 1970s, have correctly predicted global temperature changes in the 50 years since based on this data.
The measurements are real, and there is an established history of the models being generally correct (if not in specific details) by now. Climate study is not the new science you seem to think it is.
> Climate models, some dating back to the 1970s, have correctly predicted global temperature changes in the 50 years since based on this data.
Can you point me to one such model? One that actually predicted temperatures correctly back in the 1970s and not after various recent "adaptations" like "corrected" emission data?
> The measurements are real
Yes, measurements are real. Interpolations, resulting "global" temperatures and predictions aren't.
you can, in fact, compute a mean temperature for the globe. and you can, in fact, plot a trend line over that mean. and that mean is, in fact, meaningful.
no, a noisy measure around a globally increasing trend line went down.
I believe that the noisy measure goes up, on average, because it is (noisily) measuring a warming climate. I'll make that bet every year, and I will come out ahead...
using the trend line, you could set odds at which the betting on a colder 2021 would be the correct bet - but it isn't 50/50, which it would be if the process were random noise.
as a professional poker player I'm not surprised by this argument, but I am saddened.
edit: do you actually not understand the basics of statistical inference? this is like, middle-level high school math.
> * I'll make that bet every year, and I will come out ahead...*
Good luck with that, but you first asked about one year (next year), which is a different matter altogether.
> (edit: do you actually not understand the basics of statistical inference? this is like, middle-level high school math.
I completely understand your point and how you are trying to move the goalpost from an easily refutable argument to something more useful. Perhaps your "professional poker player" mind doesn't understand that recent increases/decreases in temperature averages affect next year's weather, whereas past poker games don't affect your current one.
Climate is long term patterns. Weather is what is happening at a specific time. If the distinction wasn't made then someone could argue that a cold winter day disproves warming.
I'm well aware of the distinction between weather and climate. I was asking if the climate change skeptic would take a bet that the global mean temperature (operationalized in some acceptable way) would decline in 2021 compared to 2020. If they believe that the earth is not, on average, getting hotter, then they should be indifferent to this bet (inter-year variation should be random around a fixed point).
I don't think any intellectually honest person is indifferent to this bet. Everyone believes there is a solid chance that the climate is actually getting warmer, and almost no one would wager serious money at even odds on a globally colder 2021.
If you wouldn't bet against the climate getting warmer, then I don't think you have any place calling yourself a "climate change skeptic"
In a similar vein, I invest in index funds because I'm not a market skeptic. The market (at the moment) tends to grow year over year. I put my money where my mouth is in the market, I'd do the same on global temperature, and I'd win (on average, if I bet year over year, unless something changes dramatically).
sure, but if I believe the climate is getting warmer or colder, I know where to place my bets. feel free to propose a better or more precisely defined bet.
History is dominated by the vagaries of human behavior.
Climate is a physical phenomenon which can be modeled. One problem is that humans have an effect on the climate, so models can't predict how much effort humanity is going to put into averting that change. Since that aspect can't be modeled, they produce different projections for multiple cases of human behavior: business as usual, modest efforts to change, aggressive efforts to change.
People use models to try to nail down the details, not to see whether climate change from CO2 emissions is a real thing. That's well established by physics and geological history. A good presentation of this evidence is in a couple chapters of Hansen's Storms of My Grandchildren.
Then proceed to intermediate and advanced. There are a TON of citations for your perusal. After your are done with that, the comments have some additional insights.
Have fun. This is quite the rabbit hole to dive into.
I question a lot the models as well. I think pollution is a big problem in general, but CO2 is totally the wrong focus; like focusing on the sniffles and ignoring the flu. The real issue is consumerism and consumption. We cannot buy our way out of environmental disaster, but the CO2 camp is trying to offer that option: buy green, electric cars, etc.
In realize, we need fewer cars, more trains, better transport options, cell phones that last 8 years and that are repairable rather than 1.5 year planned obsolescence Internet of Trash devices.
The debate over climate/CO2 is a religious ideology at this point, and a very unhelpful one at that.
ah yes, that anti-science. I have four publications in Geography journals and hold a BS and MS in CompSci. Your "Science" is a religious ideology of its own.
are thus an exercise in straight extrapolation based on very complex and interconnected inputs
If I throw a ball to you, your ability to put your hand approximately where it's going to be and catch it is "extrapolation based on very complex and interconnected inputs," and as it gets closer you're able to improve based on additional input.
Sure the models could all be wrong, we could be on the brink of a new ice age, and that ball could suddenly take a sharp right turn and accelerate. I wouldn't recommend putting all your money on either of those as a bet.
My argument to this would be that changing our world because of a faulty model system would be disastrous. Because of the advancements of the last two centuries more people have had food and water and basic necessities being met then at any time in history (and yet we still have billions suffering). Worsening their lives over something that might not happen is not a good way to run the world. The models being accurate is important so that if we do implement policy that end up worsening people’s lives we have proof that it is worth it.
The current consensus on the impact of climate is NOT "something that might not happen".
Climate change is happening right now, with effects that are observable as trends across the globe. Even the most optimistic model is predicting widespread catastrophe.
The models being accurate is important so that if we do implement policy that end up worsening people’s lives we have proof that it is worth it.
The models differ in the scale of how bad it's going to be, not on whether it's going to be bad. Your stance is kind of like saying "Well doc, you're telling me I have sepsis, but you can't tell me how bad that's going to be so I'm refusing treatment until you can improve your models."
Even if you ignore the statistical forecasting models, look at the natural disasters occurring every season, and the massive changes happening in glaciers and arctic regions. Forget future projections, what's wrong with acknowledging many historical records are being smashed here and now? Isn't that evidence of climactic change to you?
The best thing we can do to see if the models work is to look how they performed compared to reality in the decades since we have climate models. Turns out: They worked really, really well.
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/201...
Right, but again this goes back to OP's point that there is a survivorship bias in the models which tends the community to accept the models that both "predict" the past as well as reinforce the narrative that temperatures will continue to increase.
Having said that, the reality remains that, even without the models, the CO2 levels are increasing, they are well correlated to temperature increases, and they are expected to increase further - so VERY PROBABLY - climate change is a very serious massive problem. This is all true even without the models.
When it comes to the reliability of models, the devil is in the details. ...but, of course, no one should assume that a model turning out to be wrong or biased suddenly negates all the other evidence we have. Models are just one piece of a probability decision tree we need to navigate.
The main article's set of models are different than the ones referred to in another link someone in this thread provided, and I suspect the article you've linked will also use yet another unique set.
If it was me trying to persuade people, and all historic climate change models did indeed work really, really well, I'd make an authoritative web page that lists all of these models including their inputs and outputs, and show a detailed quantitative comparison of their outputs. I would think this approach would be more persuasive in multiple ways than hundreds of separate articles written in a narrative style, lacking numbers and consistency in sets of models.
> I’m a climate change skeptic almost entirely because I don’t trust models.
We don't need any climate models to know that Earth is warming. We can tell that just from what we know of: how electromagnetic radiation works, the basic thermodynamics of gases, determining isotope ratios of the carbon making up a sample of CO2, how much solar energy falls on the Earth, the mechanisms by which energy can leave the Earth, the amount of energy leaving Earth as measured by satellites.
That's enough to allow verifying that:
(1) a net heating of the Earth taking place,
(2) this is mostly caused by humans (mostly be emission of greenhouse gases from fossil fuels) (and yes, we can tell the difference because emissions from burning fossil fuels have a different carbon isotope ratio than other sources), and
(3) it is getting more extreme.
All you need climate models for is to try to figure out where the extra heat will end up and what it will do there.
Is it not possible to backtest these sorts of things? If it were, I would assume results would be the first bullet point on articles like this, but I also don't understand why it wouldn't be possible.
The article does sort of address this for one of the models: "The model run by NCAR, one of American’s main climate-science institutions, started producing unusual data last year while trying to reproduce the recent past. “We got some really strange results,” Gettelman said. The scientists went on to try 300 configurations of rain, pollution, and heat flows—something they can do as gods of their own digital earth—before matching the model to history. But by solving that puzzle, Gettelman’s team sent future projections upward at an unheard-of rate."
Basically, the backtesting failed to match reality for the recent past, they tweaked parameters to get it to fit, and that produced surprisingly high predictions for the future. I don't think that would leave them anything to backtest on, since they'd used effectively all their historical data to fit the model to.
> The simulations showed that the rate of Arctic warming in a world without CFCs would be cut in half – a striking effect for a category of substances that are only present in small quantities to begin with. To ensure the result was not simply a quirk of the simulation, the researchers ran the experiment using two different climate models and arrived at a similar outcome.
There is a big observational campaign happening right now that is trying to get to the heart of this called EUREC4A (main website: http://eurec4a.eu and information sheet: http://eurec4a.eu/fileadmin/user_upload/eurec4a/2019/Press/E...). The key uncertainty between different climate models is whether shallow clouds in the tropics (which in general cool the Earth through radiation) will disappear or not and make our planet even warmer - some models predict this (!)
We are 100s of individuals from more than 30 national and international partner institutions with planes, drones, ships, ground stations and autonomous buoys trying to understand how and why these clouds form, how that links to their environment, dust from Africa, the ocean current, the jetstream aloft, etc. The positions of the different platforms can be seen live on the main website and the data we are producing is appearing on there too.
If you have any questions about what we're doing I'd be very happy to help or point you towards the right people :)
I suppose my immediate question is - is there any way for an non-professional with a pair of eyes and a smartphone to contribute in a crowd-sourcy way?
Why do you want to a horde of “non-professional[s] with a pair of eyes and a smartphone” to contribute if literally hundreds of professionals with high-end equipment, meteorological observation satellites, and oodles of computational firepower are already on the task?
The main problem has never been a lack of science, the problem has always been (and alas, continues to be) a lack of political wherewithal to actually rapidly implement the drastic steps necessary to avoid the worst outcomes.
Maybe we’re finally getting what we collectively deserve?
I think what precedes the problem you mention (and one of the main points in the article) is the problem of generating reduced uncertainty in the model. Maybe there’s a chance for more granular data to enhance that?
The problem isn’t the granularity of observations, it’s the granularity of the grid with which the simulations are run. As I understand it (by analogy with my own field of macroeconomics) the current limit is the fact that the grid is coarser than the average size of a cloud, and that therefore cloud cover needs to be approximated. That is the real source of uncertainty.
Precisely. But don’t take my word for it. If you’re into a light introduction, consider watching Sabine Hossenfelder’s interview of Tim Palmer (a theoretical physicist’s interview of a leading climatologist is a thing of beauty in its own right).
I don’t know since they aren’t accompanied with comments but my hunch is they may be conflating scientific consensus with model uncertainty. I.e., if I bring up model uncertainty, then I’m casting doubt on the scientific consensus (which isn’t the case). It’s more about our confidence in the models which is the point of the article.
Nate Silver’s “The Signal and the Noise” gives a much better description than I could do
>Why do you want to a horde of “non-professional[s] with a pair of eyes and a smartphone” to contribute if literally hundreds of professionals with high-end equipment, meteorological observation satellites, and oodles of computational firepower are already on the task?
Because the Earth is huge, data collection is expensive, and funds are limited. There is a lot of [literal] ground to cover and it's perfectly feasible to augment professional work with amateur data, now that pressure, temperature, and location sensors are relatively cheap and ubiquitous.
I suppose that’s true, abstractly speaking. But does it make sense to assume that the world’s meteorological community would put satellites into geosynchronous orbit that are not suited for the purpose of observing the Earth’s atmosphere from geosynchronous orbit? I think we can safely discount that assumption.
You're assuming that "observing the Earth's atmosphere" is a yes/no question when it's actually a spectrum. I'm not familiar with the matter, but I can imagine a scenario like "We need to record a very particular part of the EM spectrum and all those existing satellites happen not to have suitable equipment for that."
> Satellites view half the globe at once. But you know that just as well as I do.
They don't, because of perspective. Even satellites in Geosynchronous orbits don't see half the globe. They are above the equator but they can never see both poles at once. Satellites closer than that only see a small part of the globe. A satellite would have to be infinitely far away to see an entire hemisphere at once.
A GPS satellite at 20000 km of altitude only sees 38% of the Earth.
Not really; you'd probably take the Folding@Home approach† to work distribution: assign each small piece as a job to N non-trustworthy "workers" (humans, computers), and then trust the results if all N results concur. If they don't, fail the job back into the work queue to be tried again later with different workers. (And maybe give the workers a reputation score, kicking out the ones who participate in enough failed jobs.)
iNaturalist.org does this for finding plants and animals but to be honest, I don't know how they deal with bad data. They even have schoolkids submitting data during class. So, kind of adversarial data collectors!
Well, thank you for that helpful suggestion. I was interested in knowing whether the research needed more data points and if so, whether a 'citizen scientist' could contribute.
http://www.cesm.ucar.edu/models/ccsm4.0/ seems to offer what you are looking for (first Google hit for “NCAR climate model source code”) but without a cluster of supercomputing nodes, what are you planning to do with it?
How do these models address overfitting? I'm sure this is taken good care of, but from just reading the article it almost sounds like some details were added to make it fit recent changes better.
You don't really optimise parameters for large scale climate models, you put in your best guess at the initial values and then wait for weeks to months depending on your goal. With function evaluations that costly, I don't really see how you have time to overfit.
The big worry is bias, a lot of assumptions about how physics can be approximated are needed to make these models, but there isn't time to test every combination of them at the full scale. So you do small scale tests and hope nothing unexpected happens in the full run.
For scale, a performance basline paper from 2018 reports achiving 0.23 simulated years per wall clock day using 4900 GPU cores [1].
Can you talk about the process of depositing materials into the atmosphere behind airplanes, euphemistically being called "Stratospheric Aerosol Injection" by the United States government? What materials are being used, how often are they being sprayed, where in the world, and what is the proposed environmental impact of blanketing the skies in the stuff?
When you go outside and look up and see streaks of stringy clouds being laid, one after another, which then spread and cover the once-blue into a giant tapestry of pulled cotton, are these all deliberate depositions of foreign material into the upper atmosphere?
It seems like sulfuric acid is one such component of the mixtures https://en.wikipedia.org/wiki/Stratospheric_aerosol_injectio... . I remember learning about the detrimental effects of acid rain in elementary school. Is it true that we've actually been spraying the skies for decades, that all the ridicule levied against those concerned by this practice has been a disinformation campaign to silence legitimate concern, and now we've codified the act in a new package to deliver to the masses so we can convince them that the thing that's been denied for so long is actually being done, and it's good for us? When you are observing cloud formation, how do you know whether it's a "real" cloud or a man-made cloud?
Why the heck are we debating about 1 degree or 2 degrees or whatever. The imperative should be to reduce emisssions as much as possible as soon as possible.
A model isn't reality. A lot of climate research is based entirely on experimenting with these climate models. Of course, the climate is a non-linear dynamic system, so even if you had a perfect model (we don't), if your input parameters were off by the slightest bit, reality would veer off wildly from your prediction within a short time. This is why weather forecasts don't work beyond 10 days.
A lot of climate research is based entirely on experimenting with these climate models.
We have a lot of data measured at many points on Earth spanning many decades. The data clearly shows that our planet is warming up and that there is a strong correlation with greenhouse gasses. One can extrapolate from these data points with certain reliability.
What is hard is to take into account are tipping points (which is why the IPCC excludes them in their projections), such as the effects of methane release from warming tundra soil. As far as I understand, most known possible tipping points only make things worse, not better.
At this point the question is not if climate change is happening (there is near universal agreement on that among climatologists), but whether it will be bad, but manageable, it will be ugly, or life-threatening to mankind. In any of these cases, we have to act now.
We have data that shows warming in the early 20th century, cooling in the mid 20th century (through the 70s) and warming in the decades after that. CO2 ppm was increasing steadily through those ups and downs, so it's not correlated perfectly. Meanwhile there are natural phenomenon like the Atlantic Multi-decadal Oscillation, the Pacific Decadal Oscillation, ENSO, NAO, etc that also correlate quite well with climate change.
In the terms of "bad, unmanageable" climate change, I would invite you to research the early Holocene, which had temps as much as 7 degrees hotter than modern temps. The early Holocene began about 12K years ago and ended about 6K years ago. The warm temperatures correlate with boom times for humanity.
See: Early Holocene Temperature Oscillations Exceed Amplitude of Observed and Projected Warming in Svalbard Lakes
I live in a small, old apartment in the EU, without proper AC. I'm pretty worried about the next summer. I can crash at a friend where the temperature never went above 26C last summer, despite a heatwave.
I always hope that if heatwaves keep coming summer after summer, governments/the UN will take tough decisions.
If nothing is done and summers are too hot, I clearly see people protesting/striking/blocking roads/etc until governments concede. My biggest fear are consumers that will refuse to adapt their consumption because they will see this as unfair rich-vs-poor restrictions. People addicted to consumerism would easily riot to denounce how capitalism ruined their living standard.
More AC units are going to make the problem worse as long as we are not using solar/wind/hydro/nuclear-power.
Last summer when there was a heat wave here, lot of people bought ACs. Next year, they are also switching them on when it's 30 degrees Celsius outside.
> because they will see this as unfair rich-vs-poor restrictions
Which, in all fairness, it is. It's not like e.g. miles travelled is similar for everyone in any society. You have the upper class with multiple international vacations (usually via airplane, cruise ship etc), you have the middle class with maybe one trip per year to a foreign country, and you have the lower classes with maybe one trip every five or ten years. "Everybody just has to cut one trip a year" really is different for the rich vs the poor, isn't it?
The same is true for many related issues. It's not the poor families that own two or three cars (because you sometimes need a small car, can't take your SUV everywhere).
What's true is that the masses will have a large impact simply because they exist in large numbers. What's not true (by a long shot) is that they consume anywhere close to what the rich consume.
legit. He's trying to mimic nature and keep the photosynthesis running by using ruminants to speed up the decomposition of organic matter and by timely management, have the regrowth sequester more atmospheric CO2 without overgrazing and compromising the grass plant or ecosystem.
331 comments
[ 3.4 ms ] story [ 352 ms ] threadSo it's not an issue of versioning (I assume they could reproduce the old results using the old data).
Could you explain this a bit more? Are you talking about data assimilation?
All PDEs are solved numerically by discretizing them into linear or nonlinear systems. If it's convex enough, Tikhonov regularization is often used.
Linear PDEs, where the solution depends only linearly on its derivatives, can be discretized into matrices. This gives a system like A m = d, where A is the discretized PDE, m is the "model" or parameter values, and d is the data. This is usually over or under-determined from the data, so it has to be solved by least squares. Since the resulting system is usually almost singular, regularization is applied, usually by penalizing the L2 norm of the model:
min || A m -d || + r ||m||^2
If it's nonlinear but convex enough, one can just solve it by fixed point iteration, with the above linear equation being solved at every step (Newton's method often doesn't work well). If it's too nonconvex, then MCMC or other Bayesian methods are better, since a single solution is useless if the parameter values could plausibly around widely separated minima.
Typically we know the basics of the physics, i.e. conservation of energy, momentum and angular momentum which set up the equations. But there a number of constitutive laws which relate parameters between these are "machine learned" but in generally, they are typically linear relations.
Like ignoring the whole climate change thing for a moment (though we absolutely should not do that), just the quality of life improvements to our health and well being this kind of mobilization would bring would be astonishing.
The wartime World War Two economy we learn about in school was only made possible because of two factors:
1) A massive surge in federal government spending, financed by borrowing from public markets (incl. war bonds), to buy the materiel needed to fight a war on two fronts (in Europe against Germany and in the Pacific against Japan). Such spending caused the public debt as a share of GDP to surge to its highest historical level ever, from about 40% at the start of the war to 100% at its peak, as you can see on this graph: https://upload.wikimedia.org/wikipedia/commons/a/a7/US_Debt_... . Today, without such a total war effort, we are running trillion dollar deficits. To put it as shortly and bluntly as I could, trying the same thing today would bankrupt the government. Our debt levels are far higher than they were then, in relative terms, and increasing by over a trillion every year. We would be looking at 2 or 3 trillion dollar deficits. Deficits of that magnitude might shake investors' confidence in the U.S.'s ability to service its debt.
2) The United States was coming out of the Great Depression, and the unemployed labor pool was in the double digits, as you can see on this graph: https://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Un... . In other words, there were a lot of unemployed people with nothing to do who could quickly be put to work to produce stuff for the war economy. This is not the case today. The economy is running at full employment. The large spare labor pool that existed then doesn't exist today.
America has a large shadow labor force. People who do not regularly apply to work are not counted as officially “unemployed.” Have to take this into account.
It signals to me that people like complaining about things, but do not participate in politics in any productive fashion. Right now it's just team sports, and most people can not name the candidate they are voting for, outside of the presidential election, until they read it off the ballot.
Transport accounts for basically a third of U.S. energy use, though it has been hardly growing over the last few years, which is a good start.
The most efficient car, bus, or train, is the one that you didn't ride.
You would hope, but sadly it depends on what lobbying group they're listening to and what industries are employing their constituents.
The impact on quality of life and society would be "astonishing," but they won't be improvements. The Soviets and Chinese tried similar "mobilization[s]" for food production. The idea was to direct society's efforts to producing enough food for everybody. Tens of millions of people died of starvation as a result. It turns out that governments are bad at running economies.
I don't know why so many people think that the same mechanism (a command-and-control economy) will lead to a different result just because you change the goal from food or industrial production to climate change mitigation.
Think also new deal / public works projects like the Hoover Dam (many died working on the Dam but not because it was a government mobilization project). Just the government spending a bunch of money on environmentally focused projects could happen and could be good.
Um, sure it did? Killing a lot of people was, in a sense, the goal.
America's WWII mobilization is really nothing like the Green New Deal. The total cost of the U.S. war effort is estimated at around $300 B (adjusted for 2009 dollars) [1]. The lowest realistic estimates for the cost of an effective Green New Deal are around double that amount every year, and lasting for decades [2].
It's true that WWII cost far more relative to GDP (over a third, versus 2% for the New Green Deal estimate above), but expressing the cost relative to GDP is not very useful in this context; in 1945 the U.S. was poised to enter a period of ten percent annual GDP growth at a time that military spending was plunging. The situation now is completely opposite; the U.S. will possibly never sustain greater than 2% GDP growth, and the Green New Deal proposes to pull money out of that for decades to come.
The character of WWII spending was also completely different. That money was largely spent on things that were pretty much guaranteed to help the war effort; materiel, industrial infrastructure, and troops. There was little risk of misallocation.
In contrast, the Green New Deal is fraught with misallocation risk. In that way, I suppose that a comparison to modern military spending is actually quite appropriate.
1 - https://eh.net/encyclopedia/the-american-economy-during-worl...
2 - https://newleftreview.org/issues/II112/articles/robert-polli...
Extrapolating a general theory from just two examples seems like a mistake.
> Pollin, however, strongly disagrees with the resolution’s aim of getting to net zero with just a decade of investment. “I think it’s completely unrealistic and it’s not worth costing out,” he said of the Green New Deal.
$1 trillion is the price tag of a much more conservative approach that puts a much longer timeline on carbon reduction:
> Edward Barbier, an economist at Colorado State University, agrees that a strict timeline isn’t realistic. He advocates jump-starting the transition by investing about 5 percent of GDP over five or so years. GDP was $20.5 trillion in 2018, according to the Bureau of Economic Analysis, so that’s a little over $1 trillion a year. “That would push us on a path to clean energy, and a path that permanently lowers carbon emissions,” he told us.
The second point I want to make is that we have much less headroom to do a "New Deal"-style project than we did in 1930. We are actually already far in excess of New Deal-era government involvement in the economy. (See my link above.) Today, government spending is at around 35% of GDP. We are in fact closer to the "total war mobilization" of World War II (where spending peaked at 45%) than to the New Deal era 18%.
So the real lesson is not that command economies are bad but rather that unforeseen circumstances should be avoided. If they hadn’t killed the sparrows we would not now be hearing about how many died.
The Four Pests Campaign is a great example of humans suffering the unintended consequences of their own stupidity and hubris. However the Great Famine had many proximal causes, and there is no evidence that simply sparing the sparrows could have prevented it.
If we go to total war to prevent climate change, that means things like:
* Shutting down power and fuel supplies to poor countries that can't afford current solar or wind power
* Military conquest of uncooperative countries
* Bombing coal mines to shut them down
* Bombing oil fields so nobody can get the oil
* Slaughtering foreign civilians to reduce their carbon emissions
When I think of a "total war" caused by an emergency response to global warming, those are the sort of consequences I imagine. Let's hope we don't get to "total war".
Steve Bannon and Trump are fans, "The authors envision a return to a more traditional, conservative social order as one outcome of a crisis. They also see the possibility of retribution and punishment for those who resist or refuse to comply with the new expectations for conformity. Mr. Trump’s “with us or against us” attitude raises questions about what kind of leader he would be in such a crisis — and what kind of loyalty his administration might demand." https://www.nytimes.com/2017/04/08/us/politics/bannon-fourth...
"If they do not yield — kill all males", says the terrorist christians: https://en.wikipedia.org/wiki/Matt_Shea#%22Biblical_Basis_fo...
Vast overuse of energy resources is a pattern intertwined with modern life, from housing to transportation to food to recreation. The people demand having a vehicle with more than 100hp at their whim. Now picture a herd of 100 horses for every person on Earth. It is political suicide to propose cutting down to ecological sustainable levels of 1 horse per person. That's before we take in account the population explosion of 5-10-20x compared to pre-industrial levels. Not sure where you even begin implementing policies to reduce the population levels to ecological sustainable levels.
As a species, we are simply incapable to comprehend that the way out of poverty is intelligent frugality. Instead, we attempt to brute force our way. The effort needed to fall back into an ecological sustainable band far surpasses WW2, and no one wants to hear about the actual costs. Nothing will change until mother Nature will do the change for us. The hard way.
In my opinion, these approaches completely fail at solving large issues that require large orchestrated efforts that require things at state, nation, and even world scale and longer timescales than an individual or their kids.
We haven't really developed a 'hammer' for those sort of problems and that hammer keeps competing with our 'saw' we use on the other problems whose proponents want to only use their 'saw' for every problem they see, ignoring its shortcomings.
The problem with climate change is that it is really expensive to fix with highly uncertain costs to do so.
So it's not expensive in any long-run calculation, only the short-run.
Nor is cost net negative if you use high discount rates and try lower co2 targets (e.g. 3 degrees warming by 2100 is much more likely to have positive ROI than say holding 2 degrees). Huge controversy around protecting against lower probability, highly destructive scenarios. Point is there's lots of controversy here.
https://en.m.wikipedia.org/wiki/Economics_of_climate_change_...
Comparisons to a war are overly dramatic because it puts the destruction on the opposite side of the effort. If you're in a war and two countries spend a trillion dollars fighting the war, those resources go to causing trillions of dollars of damage to the other country -- most of the cost of the war is getting bombed, not making bombs. With climate change it's the opposite -- the more we do against it, the less damage there is overall. On top of that, most of the "costs" are just replacing other costs -- you have to spend money building solar panels, but then you don't have to spend money doing oil exploration or mining coal, which offsets most to all of the cost.
On top of that, wars are characteristically fought by governments with all the bureaucratic inefficiency that implies, whereas the single biggest thing we could do against climate change is to accurately price carbon and then let the market find the most efficient way to optimize it out.
Obviously that doesn't get us out of actually doing it, but the biggest problem isn't that it's actually that hard from an economic perspective, it's that it's hard from a political perspective because the oil industry has a trillion dollar interest in not ceasing to exist.
> While it is true that we estimated damages as high as 10% of GDP annually at the end of the century for warming of 15°F above pre-industrial levels, the odds of a temperature change that would drive damages of this magnitude are slim. In fact, they are less than 1-in-100 by our original calculation. Under a scenario of continued growth in global emissions, 9-out-of-10 global change temperature projections fall approximately in the range of 4°F to 11°F by 2100. The median change is closer to 6°F. We deliberately incorporate tail risks in our research, not just “most likely” outcomes, because consideration of tail risks is crucial to sound risk management.
> In other words, if global GDP doubles or halves by 2100, the results suggest real GDP per capita would still be 7.22% below where it would be otherwise.
For most of the world, an RCP8.5 scenario is equivalent to knocking out 3-4 years of GDP growth. Bad, but not catastrophic, and probably less bad than the impact of "WWII-style mobilization" and shifting the economy into command-and-control mode.
> Our localized approach to studying the relationship between climate and society reveals that the burden is spread unevenly. In many counties, GDP decline could total more than 10% by 2100, and in the worst-hit county, Florida's Union County, losses could near 28% for a likely warming scenario under continued emissions growth (the 7°F median change, not the extreme 15°F change highlighted in press coverage). The combined tally almost certainly understates the extent of the damages, because the worst effects are concentrated in places where incomes are lowest. Tumbling incomes in poor counties have a correspondingly small impact on nationwide GDP, meaning the economic burden of climate change is reduced because it falls on those with low incomes.
> If the burden is spread evenly, 1% or 2% of national GDP might seem manageable, but we will not all be equal in the face of climate change. Across the United States, there will be winners and losers. What is lost in all of this noise is the sad fact that even those smaller numbers are too high a cost. They come from a subset of outcomes that are well-measured. As ever in this debate, it is important that we look beyond the headlines, beyond the averages, and examine the people at the heart of the issue. Look at the mass of evidence that points to people who will actually be negatively affected by climate change. They are not abstract people not-yet-born and in some far-off land. They are your neighbors. They are your friends. They are you. Combining local climate projections with historical observations yields a personalized, evidence-based outlook of future risk. Our ongoing research is mapping out these local impacts across the globe.
That sounds pretty catastrophic.
[1]W. Nordhaus, “Projections and Uncertainties about Climate Change in an Era of Minimal Climate Policies,” American Economic Journal: Economic Policy, vol. 10, no. 3, pp. 333–360, Aug. 2018, doi: 10.1257/pol.20170046.
edit: This comment is currently sitting at -2. If you think a 1.5° target is optimal, you should explain why you think so rather than just down voting this post. The paper I linked to is by William Nordhaus who won the Nobel Prize for economics in 2018 for his work related to the economics of climate change.
There’s a nice article here on the issue and frustration of clouds for climate modelers by the head of the Royal Meteorological Society here: https://www.carbonbrief.org/guest-post-why-clouds-hold-key-b...
> they don’t like it
Who? HNers? I don’t care. I think it more that people don’t like seeing themselves as the virus or cancer, when we could easily change our behavior and we wouldn’t be.
The big question is then of course whether the new cloud model is wrong and the temperature increase therefore as well, or whether the new cloud model is more accurate than previous ones and the temperature increase is a real effect.
I found another article that looks at this in a bit more detail:
https://news.ucar.edu/132678/ncars-new-climate-model-running...
The linked paper this is based on has the following as the last sentence:
> What scares us is not that the CESM2ECS is wrong (all models are wrong, [Box, 1976]) but that it might be right.
For this reason, I'm skeptical of models that try to simulate very complex systems with a lot of variables and feedback loops. Models that have a large number of variables are particularly difficult to get right because different tiny mistakes in various parts of the model can compound and yield completely arbitrary and contradictory results. Approximating the reality in software is almost impossible.
[1] https://en.wikipedia.org/wiki/Chaos_theory
'Hopefully' is doing a lot of work there. In modeling a highly dimensional dynamic system it's not obvious that a smaller cell size will lead to more accurate predictions.
Not to diverge, but I'd be extremely wary of editorial bias/spin from this particular publication until November or so.. which is not to say that the topic itself is suspect - as you point out, the big question is if the updated model is actually worse than previous models or if it is better
Currently studying solar energy transfers via hot solar particles, latest hot topic.
https://addons.mozilla.org/en-US/firefox/addon/temporary-con...
Disabling scripts generally doesn't break these types of sites but it does stop them from detecting whatever it is they are trying to detect.
Ironically, socialism is being sold as a solution that you yourself make very clear. That, the pace of scientific progress is really fast ,and automation is going to make a lot of jobs obsolete.
Socialism (in the nordic sense, ie. capitalism with social welfare) is being proposed as a solution to rising inequality and unregulated for-profit forces in the free market of industries where the consumer has no choice. (medicine, education)
> "So we can't throw them out yet."
This might be an elementary view of science, but I think there is a danger here that while everyone is making their models, if anyone is an outlier they go and tweak their model to match the patterns of others: 'Klaus Wyser’s group "switched off" some of the new cloud and aerosol settings in their model, he said, and that sent climate sensitivity back down to previous levels'. That seems to me a questionable reason to "switch off" part of the model - you should create the most accurate simulation possible and trust the output, not tweak the inputs to match literature data.
If your model produces wildly different results from previous models, either you hit on some really big discovery or you made a mistake. An ethical scientist will try to rule out the latter possibility before accepting the former.
One pretty general debugging/analysis strategy for a complex model is to deactivate it piece by piece until you get it to a point where it should reproduce a result that you can verify by other, independent means. E.g. tweak the parameters of the model so that reproduces a result that is known analytically. For instance, whenever it is possible in a model, a good sanity check is to set parameters that must lead to e.g. a perfect conservation of certain quantities.
And it does not make a credibility issue. This is how science works — it is a process that strives to be as accurate as possible, not come up with a static answer and stick to it (that’s what religion does).
The ability for science to change and adapt is what makes it so strong. That is the message that needs to always be driven when discussing science; not throwing hands in the air and saying “why do these scientists keep changing their answers? They obviously don’t know what they’re doing”
> The ability for science to change and adapt is what makes it so strong
To me this article is them _resisting_ change, looking for a reason NOT to accept it, because it goes against what they previously said. Maybe this is all to early, and in a year or so we will be seeing 4 or 4.5 degree predictions, but this article describes them trying to change their inputs to match previous answers, not getting new answers.
Just imagine they would go public with this "Scientists found climate change is worse than previously thought with updated model" and then weeks later find an error in the changes made to the model "Scientists made mistakes, climate change less severe than previously thought".
What do you think would hurt their credibility more?
They are not throwing away their findings and they are not burying it. They are working to valdiate/invaldiate them, because they are scientists.
Indeed, even people we nowadays consider brilliant minds of their time, encountered plenty of resistance [0] during these very same times because their proposed ideas just seemed too outrageous.
[0] https://en.wikipedia.org/wiki/Criticism_of_the_theory_of_rel...
What you're saying is that you have established a prior that undermines all further evidence presented to you, because it has changed substantially in the past. However, that seems irrational to me.
There are two basic modes of reducing pollution. Technological advancement, and conservation.
In the case of technological advancement, you get less pollution per unit of output as the same or lower cost. As long as capital is fairly cheap, these advances tend to propagate quickly through a competitive market.
In the case of conservation, it’s more a question of which groups of people should conserve (i.e. suffer) for this outcome, and by how much.
I'm seriously wondering why there is any reason to oppose technological progress at all. What can they possibly gain by sticking to the old technology? Who's going to benefit from something so short sighted?
We have known the rough level of the climate sensitivity (delta T per doubling CO2) in the current macro state for decades. We have observed it. This science is incredibly settled. We don't know where the tipping elements are and we don't know how the impacts will be distributed.
Questioning the credibility of people calling for action might look like you are being the circumspect and rational one, asking for action proportionate to the evidence. In reality you are endorsing an ignorant position that ignores the evidence we have. If this is not wilful ignorance then please read up on this. The IPCC report summary is a good spot to start. Sceptical Science also often provides good writeups: https://skepticalscience.com/climate-sensitivity.htm
The fundamental physics that drive the sensitivity are straightforward. Energy balance and water vapour. That gets you a ballpark figure that is confirmed by the last 100 years of emissions.
It is a denier talking point to claim that we just don't know enough, or that the models are always being tweaked and we should just wait until scientists have "the final answer" before doing anything.
Hey, let's stop giving NOAA weather forecasts because they aren't 100% accurate. Let's close down the stock market until everyone can decide what the values should be. Let's disband the military because not all military leaders have the same opinion.
If we are mature enough to recognize that imperfect but credible models are worth acting on in other domains, why do we hold climate change to impossible standards?
Given that, how could you possibly advocate for doing nothing?
> This is how science works — it is a process that strives to be as accurate as possible, not come up with a static answer and stick to it (that’s what religion does).
That's fine. Many public policy advocates throw around the term 'settled science'. But based on what you said, is there such a thing?
From the article:
Climate models have been doing a fine job projecting warming for a long time. A recent study compared models as old as 1970 with observations made in the decades since. Some models warmed up too much, and some too little, but 14 of 17 past projections turned out to be consistent with the measured path of global average temperatures.
Scientists can not give definite answers in such complex systems, but it is the closest we can get in extrapolating the trajectory that we are on and computing what the effect of various measures is.
I am not sure what else one could base policy on.
Yes, there is. Just because there is no absolute certainty, doesn't mean it's all just baseless speculation. Just because, as a matter of scientific methodology, atomic theory is not absolutely certain (i.e., we could hypothetically find evidence that contradicts the model), doesn't mean someone just made it up and it has no predictive power.
If you change your model (hypothesis) to fit the facts, your model is merely descriptive of the evidence that is already available, and useless for prediction - as proven by the act of changing the model. That's how science works.
If you want to cast it in the rigid hypothesis testing language (not a very good description of the actual practice), the description is this:
A physically motivated modification to existing tools lead to unexpected results that are not understood yet. As part of figuring out the cause of the new result they are running a series of smaller experiments to test various hypothesis of what aspects of the modifications matters most for the new results.
In effect, objecting to the practice of turning things off and on again is to object to the very notion of doing experiments, which is not very scientific.
To point out just how wrong your misinterpretation is, the very next sentence has the "why":
> A new research paper co-authored by Zelinka from the Lawrence Livermore National Lab likewise pointed to the role of virtual clouds in determining the results.
The key phrase being "role of virtual clouds." The motivation wasn't to slavishly reproduce results from the literature, and to even suspect that it completely outside the bounds of reasoned discourse. It comes across as if you are trying your hardest to find something to nitpick, some small phrase that you can misinterpret in order to raise doubts in those who aren't paying close attention.
This is exactly how denialists and propagandists behave.
I can't ding the climate scientists too much, though... I'm not sure there's a better way to study this stuff.
But I'm only a bit surprised this would be such a controversial opinion here.
http://calteches.library.caltech.edu/51/2/CargoCult.htm
If you are unfamiliar with climate sensitivity, this is a good place to start: https://skepticalscience.com/climate-sensitivity.htm
So we actually did an experimental test of the predictions made in 1970, and those predictions turned out to be largely correct.
We should probably halt this experiment on ethical grounds.
Sadly the political activists have hijacked the normal scientific process. And this allowed some pseudoscience (with alarming predictions or alarming observations) to mix in too.
In some science news I read that the Arctic Ice-sheet is growing back, and that Envisat showed that the oceans were not rising. So very likely the climate is more complex than some alarmed scientists thought.
[0]http://omegataupodcast.net/326-weather-forecasting-at-the-ec...
> One question modeling can help answer is called “climate sensitivity,” an estimate of how much warmer the planet will be once it has adjusted to atmospheric CO₂ at double the pre-industrial level. (At current rates, CO₂ could reach a doubling point in the last decades of this century.) This is the old, reliable number that’s come out to 3°C for 40 years. It was as close as anything gets to certainty.
I'd be curious where your impression comes from, in terms of what sources of information you're receiving.
I think 5 out of 8 is not a very strong difference from 4 out of 8, which is the comparison that makes sense in this context.
Perhaps literally all historic climate models have been accurate, I've read extremely enthusiastically received articles suggesting as much.
I finally decided to do something about it last fall. I researched and have committed to purchasing green power. Every month I purchase 850 kWh for $22 from Bullfrog Power (a Canadian company, I have no affiliation). It's much more reasonable than I thought. I still conserve as much as I can but $22/month allows me to feel like I am doing something. If in 40 years, my kids ask me what I did to prevent climate change, I feel like I'll have an answer I'll be proud of.
Have you considered your next step, and do you have any suggestions? Purchasing green power is such a minor sacrifice for my household, I'm still looking for something more.
Trying to solve it on individual goodwill of course helps but is not enough by itself.
Doesn't it kind of feel like this is the equivalent of a kid in the 70's asking why their parents didn't stop World War 2? We absolutely need to be as vocal as possible, but as individuals, outside of trying to get people with power to affect the change we need, I don't know what we can expect to accomplish. You just can't do enough diet modifications, carbon footprint reduction, or recycling to have it matter on a global scale.
I used to think like that. I used to think "There's nothing I can do, why do anything." Then I had kids and I realized that I need to be able to tell them I did something. Our world might be a wasteland of burnt forests and flooded cities, but at least I will be able to look my children in the eye and say "I tried."
You can follow this logic all the way down to an individual level.
If China doesn't do anyting, the US doesn't have to do anything either. If the US doesn't do anything, Germany doesn't have to do anything either. If not Germany, then not Munich. If not Munich, then not our little town. If not our neighbor, then me neither.
Everybody and every country should do whatever they can. Will it be enough? Probably not. But you gotta start where you actually have some control.
Don't fall into the trap that there's no reason to change your own habits because you think individual action doesn't matter. It does. But you're also right that it isn't enough.
[1] US EPA, 2017, "The transportation sector generates the largest share of greenhouse gas emissions. ... The largest sources of transportation-related greenhouse gas emissions include passenger cars and light-duty trucks, including sport utility vehicles, pickup trucks, and minivans. These sources account for over half of the emissions from the transportation sector." https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...
[2] Same source, 29% of emissions from Transportation; more than half that from commuter cars.
I honestly struggle to understand this statement in the context of discussing individual action. Making public transit a reasonable option for most personal transportation in the US would be a public works project on the scale of the New Deal.
Perhaps more importantly, cutting US emissions by 10% is very nearly inconsequential unless it is part of a coordinated effort that is driving global emissions down by significantly more than 10%.
I don't agree. Most large-ish cities already have quite good public transportation networks, but outside of a couple special places like NYC, Chicago, and maybe SF, they're not the default option. If the demand is there, adding more bus routes and increasing frequency is trivial. Adding more rail and subway lines is definitely a major task, but we spend more on garbage like the TSA and the F-35 than we do on increasing public transit options; it's hardly a task on the order of the New Deal.
My overall point is individual action is a major factor in transit emissions, which is a major source of carbon, and thus individual action does have an impact on our climate change future. The fact that individual action alone isn't enough to fix the problem isn't an excuse for individuals to avoid making choices to lower their emissions.
> Perhaps more importantly, cutting US emissions by 10% is very nearly inconsequential unless it is part of a coordinated effort that is driving global emissions down by significantly more than 10%.
I don't agree at all that decreasing US emissions by 10% is inconsequential[1], but yes, of course, it is not enough. I already agreed with you that individual action is not enough. But it is significant. I'm trying to back up that assertion with numbers.
[1] Ten percent of US emissions is about 1.37% of global emissions, https://en.wikipedia.org/wiki/List_of_countries_by_carbon_di...
That's because the power companies want to keep people from developing competition to them... if enough individuals install solar plants with battery storage, eventually they power company simply won't be needed any more, which is what they're trying to avoid.
By selling "green" feel good power, they quiet the impulse that people like you get to make changes that would impact their business.
It's still good that you choose to purchase green power over e.g. coal fired power, but it's also the power companies you're keeping in business that are causing a lot of climate change, and who have contributed to it all along.
edit: also it is very rare to have the externalities included into the sum of CO2 emissions (dams need cement, wind turbines need steel, solar panel need mining, we need to transport these components, etc. -> all of that is probably not currently powered by CO2 neutral energy).
Is there a typo somewhere? I run multiple computers at home 24/7 and I'm using ~2500 kWh a year. Also, 850 kWh for $22 sounds crazy cheap, I pay ~100€ per 200kWh (including the rented meter, but more importantly, taxes).
https://youtu.be/YkA65vpeA5g
That too, yeah. Though they are primarily subsidized by not paying taxes on energy, they're not paying negative prizes (yet).
The article talks about it a little bit about how the models are used to predict the 19th century to see if they are correct. But the models use the last 100 years as input so of course it will give you accurate output. But the real challenge of the models would be to accurately predict things that are not part of the inputs into the model. I don’t believe that these models can do this and are thus an exercise in straight extrapolation based on very complex and interconnected inputs.
What makes such a measurement an "invalid form"?
The measurements are real, and there is an established history of the models being generally correct (if not in specific details) by now. Climate study is not the new science you seem to think it is.
Can you point me to one such model? One that actually predicted temperatures correctly back in the 1970s and not after various recent "adaptations" like "corrected" emission data?
> The measurements are real
Yes, measurements are real. Interpolations, resulting "global" temperatures and predictions aren't.
HadCRUT4 (from UK Met Office Hadley Centre and the University of East Anglia’s Climatic Research Unit)
GISTEMP from the NASA GISS
MLOST from the NOAA
JMA from the Japan Meteorological Agency
I'm open to other datasets. I'm not choosy.
I believe that the noisy measure goes up, on average, because it is (noisily) measuring a warming climate. I'll make that bet every year, and I will come out ahead...
using the trend line, you could set odds at which the betting on a colder 2021 would be the correct bet - but it isn't 50/50, which it would be if the process were random noise.
as a professional poker player I'm not surprised by this argument, but I am saddened.
edit: do you actually not understand the basics of statistical inference? this is like, middle-level high school math.
Good luck with that, but you first asked about one year (next year), which is a different matter altogether.
> (edit: do you actually not understand the basics of statistical inference? this is like, middle-level high school math.
I completely understand your point and how you are trying to move the goalpost from an easily refutable argument to something more useful. Perhaps your "professional poker player" mind doesn't understand that recent increases/decreases in temperature averages affect next year's weather, whereas past poker games don't affect your current one.
I don't think any intellectually honest person is indifferent to this bet. Everyone believes there is a solid chance that the climate is actually getting warmer, and almost no one would wager serious money at even odds on a globally colder 2021.
If you wouldn't bet against the climate getting warmer, then I don't think you have any place calling yourself a "climate change skeptic"
In a similar vein, I invest in index funds because I'm not a market skeptic. The market (at the moment) tends to grow year over year. I put my money where my mouth is in the market, I'd do the same on global temperature, and I'd win (on average, if I bet year over year, unless something changes dramatically).
The climate isn't getting warmer or colder just because next year's temperature does.
Climate is a physical phenomenon which can be modeled. One problem is that humans have an effect on the climate, so models can't predict how much effort humanity is going to put into averting that change. Since that aspect can't be modeled, they produce different projections for multiple cases of human behavior: business as usual, modest efforts to change, aggressive efforts to change.
Start here: https://skepticalscience.com/empirical-evidence-for-co2-enha...
Then proceed to intermediate and advanced. There are a TON of citations for your perusal. After your are done with that, the comments have some additional insights.
Have fun. This is quite the rabbit hole to dive into.
What was the CO2 ppm in the early Holocene? Why was the early Holocene so much warmer than today in spite of lower CO2 concentrations?
Early Holocene Temperature Oscillations Exceed Amplitude of Observed and Projected Warming in Svalbard Lakes
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201...
Here's one of them from that page, chosen at random: https://www.tandfonline.com/doi/abs/10.5589/m04-044
A blog page linking a bunch of academic papers is as good as a hackernews comment linking a bunch of academic papers.
Your linked paper is about arctic temperatures, not global average temperatures.
In realize, we need fewer cars, more trains, better transport options, cell phones that last 8 years and that are repairable rather than 1.5 year planned obsolescence Internet of Trash devices.
The debate over climate/CO2 is a religious ideology at this point, and a very unhelpful one at that.
Taliban
If I throw a ball to you, your ability to put your hand approximately where it's going to be and catch it is "extrapolation based on very complex and interconnected inputs," and as it gets closer you're able to improve based on additional input.
Sure the models could all be wrong, we could be on the brink of a new ice age, and that ball could suddenly take a sharp right turn and accelerate. I wouldn't recommend putting all your money on either of those as a bet.
You don't have to believe the models:
https://www.fooledbyrandomness.com/climateletter.pdf
Climate change is happening right now, with effects that are observable as trends across the globe. Even the most optimistic model is predicting widespread catastrophe.
The models differ in the scale of how bad it's going to be, not on whether it's going to be bad. Your stance is kind of like saying "Well doc, you're telling me I have sepsis, but you can't tell me how bad that's going to be so I'm refusing treatment until you can improve your models."
Pascal's wager has no information. You know nothing of the state of god's existence.
The precautionary principle uses current equalibrium as the default.
The current working equalibrium embeds information.
The precautionary principle does not state it will result in the best outcome. Only that it's more likely to not have the worst.
Having said that, the reality remains that, even without the models, the CO2 levels are increasing, they are well correlated to temperature increases, and they are expected to increase further - so VERY PROBABLY - climate change is a very serious massive problem. This is all true even without the models.
When it comes to the reliability of models, the devil is in the details. ...but, of course, no one should assume that a model turning out to be wrong or biased suddenly negates all the other evidence we have. Models are just one piece of a probability decision tree we need to navigate.
Does "they" refer to all models?
The main article's set of models are different than the ones referred to in another link someone in this thread provided, and I suspect the article you've linked will also use yet another unique set.
If it was me trying to persuade people, and all historic climate change models did indeed work really, really well, I'd make an authoritative web page that lists all of these models including their inputs and outputs, and show a detailed quantitative comparison of their outputs. I would think this approach would be more persuasive in multiple ways than hundreds of separate articles written in a narrative style, lacking numbers and consistency in sets of models.
We don't need any climate models to know that Earth is warming. We can tell that just from what we know of: how electromagnetic radiation works, the basic thermodynamics of gases, determining isotope ratios of the carbon making up a sample of CO2, how much solar energy falls on the Earth, the mechanisms by which energy can leave the Earth, the amount of energy leaving Earth as measured by satellites.
That's enough to allow verifying that:
(1) a net heating of the Earth taking place,
(2) this is mostly caused by humans (mostly be emission of greenhouse gases from fossil fuels) (and yes, we can tell the difference because emissions from burning fossil fuels have a different carbon isotope ratio than other sources), and
(3) it is getting more extreme.
All you need climate models for is to try to figure out where the extra heat will end up and what it will do there.
Basically, the backtesting failed to match reality for the recent past, they tweaked parameters to get it to fit, and that produced surprisingly high predictions for the future. I don't think that would leave them anything to backtest on, since they'd used effectively all their historical data to fit the model to.
> The simulations showed that the rate of Arctic warming in a world without CFCs would be cut in half – a striking effect for a category of substances that are only present in small quantities to begin with. To ensure the result was not simply a quirk of the simulation, the researchers ran the experiment using two different climate models and arrived at a similar outcome.
https://www.theglobeandmail.com/canada/article-cfcs-are-a-ma...
The danger here is that there's something else we fundamentally don't understand about the atmosphere.
We are 100s of individuals from more than 30 national and international partner institutions with planes, drones, ships, ground stations and autonomous buoys trying to understand how and why these clouds form, how that links to their environment, dust from Africa, the ocean current, the jetstream aloft, etc. The positions of the different platforms can be seen live on the main website and the data we are producing is appearing on there too.
If you have any questions about what we're doing I'd be very happy to help or point you towards the right people :)
The main problem has never been a lack of science, the problem has always been (and alas, continues to be) a lack of political wherewithal to actually rapidly implement the drastic steps necessary to avoid the worst outcomes.
Maybe we’re finally getting what we collectively deserve?
Perhaps you should tell the people who are running the "big observational campaign happening right now" that they can pack up and go home.
Nate Silver’s “The Signal and the Noise” gives a much better description than I could do
Because the Earth is huge, data collection is expensive, and funds are limited. There is a lot of [literal] ground to cover and it's perfectly feasible to augment professional work with amateur data, now that pressure, temperature, and location sensors are relatively cheap and ubiquitous.
They don't, because of perspective. Even satellites in Geosynchronous orbits don't see half the globe. They are above the equator but they can never see both poles at once. Satellites closer than that only see a small part of the globe. A satellite would have to be infinitely far away to see an entire hemisphere at once.
A GPS satellite at 20000 km of altitude only sees 38% of the Earth.
https://www.wtamu.edu/~cbaird/sq/2013/05/10/since-one-satell...
† does this general strategy have a name?
https://www.climateprediction.net/
I used to work for them a few years ago.
[1] https://boinc.berkeley.edu/
[2] https://www.cpdn.org
The big worry is bias, a lot of assumptions about how physics can be approximated are needed to make these models, but there isn't time to test every combination of them at the full scale. So you do small scale tests and hope nothing unexpected happens in the full run.
For scale, a performance basline paper from 2018 reports achiving 0.23 simulated years per wall clock day using 4900 GPU cores [1].
[1]: https://www.geosci-model-dev.net/11/1665/2018/gmd-11-1665-20...
It seems like sulfuric acid is one such component of the mixtures https://en.wikipedia.org/wiki/Stratospheric_aerosol_injectio... . I remember learning about the detrimental effects of acid rain in elementary school. Is it true that we've actually been spraying the skies for decades, that all the ridicule levied against those concerned by this practice has been a disinformation campaign to silence legitimate concern, and now we've codified the act in a new package to deliver to the masses so we can convince them that the thing that's been denied for so long is actually being done, and it's good for us? When you are observing cloud formation, how do you know whether it's a "real" cloud or a man-made cloud?
We have a lot of data measured at many points on Earth spanning many decades. The data clearly shows that our planet is warming up and that there is a strong correlation with greenhouse gasses. One can extrapolate from these data points with certain reliability.
What is hard is to take into account are tipping points (which is why the IPCC excludes them in their projections), such as the effects of methane release from warming tundra soil. As far as I understand, most known possible tipping points only make things worse, not better.
At this point the question is not if climate change is happening (there is near universal agreement on that among climatologists), but whether it will be bad, but manageable, it will be ugly, or life-threatening to mankind. In any of these cases, we have to act now.
In the terms of "bad, unmanageable" climate change, I would invite you to research the early Holocene, which had temps as much as 7 degrees hotter than modern temps. The early Holocene began about 12K years ago and ended about 6K years ago. The warm temperatures correlate with boom times for humanity.
See: Early Holocene Temperature Oscillations Exceed Amplitude of Observed and Projected Warming in Svalbard Lakes
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201...
I'd say all of thinking is based entirely on experimenting with mental models. Are you saying your thinking is invalid? :))
I always hope that if heatwaves keep coming summer after summer, governments/the UN will take tough decisions.
If nothing is done and summers are too hot, I clearly see people protesting/striking/blocking roads/etc until governments concede. My biggest fear are consumers that will refuse to adapt their consumption because they will see this as unfair rich-vs-poor restrictions. People addicted to consumerism would easily riot to denounce how capitalism ruined their living standard.
Last summer when there was a heat wave here, lot of people bought ACs. Next year, they are also switching them on when it's 30 degrees Celsius outside.
The irony.
Which, in all fairness, it is. It's not like e.g. miles travelled is similar for everyone in any society. You have the upper class with multiple international vacations (usually via airplane, cruise ship etc), you have the middle class with maybe one trip per year to a foreign country, and you have the lower classes with maybe one trip every five or ten years. "Everybody just has to cut one trip a year" really is different for the rich vs the poor, isn't it?
The same is true for many related issues. It's not the poor families that own two or three cars (because you sometimes need a small car, can't take your SUV everywhere).
What's true is that the masses will have a large impact simply because they exist in large numbers. What's not true (by a long shot) is that they consume anywhere close to what the rich consume.
https://www.ted.com/talks/allan_savory_how_to_fight_desertif...