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Economists have fit ludicrously inadequate functions to model the effects of temperature increase on GDP. They disregarded rainfall and physics in general.

I feel betrayed by the IPCC for treating these studies seriously. This is particularly of concern, since the IPCC was created specifically as a non-industry scientific body to help policymakers.

I apologize for further propagating the false sense of security in a previous Ask HN[1]. But I thank elviejo[2] for linking me to this video. I published it again, because I think it is the most important discussion of the century.

1 - https://news.ycombinator.com/item?id=33999229

2 - https://news.ycombinator.com/item?id=33999547

For those who prefer text, the paper is here: https://mahb.stanford.edu/wp-content/uploads/2021/07/The_app...

danukar, you deserve respect for so publicly questioning and then changing direction on your prior assumptions.

I also thank the HN community (and dang) for enabling such discussion.

I tried to voice my concerns in /r/AskScience, but my post was not phrased in a sufficiently scientific manner. I asked why we ought to combat climate change, rather than scientifically answerable issues about the damage models.

Who is this guy? He is contradicting economic analysis that’s been incorporated into IPCC reports. He uses the phrase “so called Nobel Prize.” He isn’t even currently a professor at any institution. He’s apparently supporting his research with “crowd sourced funding.” https://en.wikipedia.org/wiki/Steve_Keen

Apart from that, the gist of his critique seems to be that economists are using linear extrapolations and aren’t incorporating “tipping points” into their analysis. But its the climate scientists at the IPCC itself who have consistently declined to give tipping points and runaway effects significant weight. That’s true even in the latest 2022 IPCC report: https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6.... The strongest thing the executive summary says about “tipping points” is that certain ones “cannot be ruled out.”

The Economics Nobel isn't considered a real "Nobel Prize":

https://en.wikipedia.org/wiki/Nobel_Memorial_Prize_in_Econom...

He's right to question Nordhaus, but I don't think the rest of his stuff is particularly out of the mainstream of economics, though he quotes a kook on minerals, he still ends up with carbon pricing as the fix.

Also, IPCC scientists aren't dismissing tipping points, they're just hard to model and unnecessary, as even without them (for good and bad, e.g. cheap solar tipping points), dealing with climate change makes financial sense.

Why is he right to question Nordhaus? Nordhaus literally won a Nobel prize for studying the economics of climate change.
Those assumptions seem reasonable to me. What’s the gist of the criticism?
For one, the "integrated" damage model does not use any climate data other than temperature. Rainfall, for instance, is crucial for agriculture, but is ignored. Note the parameters of the model:

https://web.archive.org/web/20141014141710/http://www.econ.y...

Secondly, the damage function is a quadratic polynomial (see the parameters a1 and a2 in the formula). But that is an unreasonable assumption, as heating can induce exponential or logistic effects (or worse). More explanations about this by prof. Keen starting 14:42 in the video:

https://youtu.be/5LvyxH3O7kE?t=882

Take, for instance, a phase change. Water boils at 100°C extremely nonlinearly compared to temperature. In fact, in a stepwise manner.

> He isn’t even currently a professor at any institution.

Steve Keen is a (retired) Australian economist who has held some senior positions at institutions around the world.

He holds heterodoxical views on a number of economic topics and has predicted, several times, the collapse of the Australian economy due to the continued strong growth in the housing market.

Is he wrong about climate science? Not sure, but it's not his area of expertise. However I also suggest that the IPCC are not a trusted source (IMO) in this argument, especially given they are essentially a political tool rather than a scientific one.