I read the entire article and agree with most of it. I don't agree with: "All of this helps explain why IPCC anticipates climate change will have a modest impact on economic growth. By 2100, IPCC projects the global economy will be 300 to 500% larger than it is today. Both IPCC and the Nobel-winning Yale economist, William Nordhaus, predict that warming of 2.5°C and 4°C would reduce gross domestic product (GDP) by 2% and 5% over that same period." I don't know what the reference point is for 2.5 degree C. and 4.0 degree C. warming. I'll assume that it is from the late 19th century. I think that the economic affects will be more severe and the potential for several meters of sea level rise will be high. Most of that sea level rise would occur after the year 2100. Severe weather
coupled with a meter or more of sea level rise could be catastrophic for many urban areas. I don't know about the practicality or cost of building sea walls to protect areas prone to sea level rise or
if that was figured into the economic cost.
Here is an opinion from Wikipedia - William Nordhaus.
Criticisms[edit]
Economist Professor Steve Keen has severely criticized Nordhaus work and said that his claim that a 4°C increase in global temperature over pre-industrial levels is only going to reduce GDP per capita by between 2% and 4% is nonsense. Keen disagrees that Nordhaus's "Damage Function" should be a quadratic equation. To show how absurd it is he says that since his damage function is symmetrical "it predicts precisely the same level of damage to GDP from a fall of, for example, 4°C in the global average temperature, as it does for a rise of 4°C." If we try to apply the function to a period we had 20,000 years ago, during the last Ice Age, where countries like Canada, Ireland, Scotland, northern Germany, Poland, Denmark, Norway, and Sweden were under a kilometer or more of ice, the function would also estimate a reduction of GDP by 2% and 4%. [32]
Professor Steve Keen's also gave a presentation "Flawed Approaches (and a New Approach) to Environmental Challenges" at the OECD Conference "Averting Systemic Collapse" in Paris on September 18th 2019 criticizing in detail why he believes Nordhaus's work is fatally flawed. In one of his slides, he shows that 4°C of warming would mean that approximately 6.7 billion people die, which is incompatible with the idea that GDP would only be reduced by a few per cent. [33]
Others have also pointed out that climate scientists and ecologists have a very negative opinion of Nordhaus. Dr. Jason Hickel, who researches ecological economics, writes that "Many believe that the failure of the world’s governments to pursue aggressive climate action over the past few decades is in large part due to arguments that Nordhaus has advanced." One of his criticisms is that Nordhaus uses a very high discount rate which allows him to argue that we shouldn’t reduce emissions too quickly, because the economic cost to people today will be higher than the benefit of protecting people in the future. [34]
Most climate scientists assume non-linear impacts [35]. This had not been properly accounted for by Nordhaus in the 1980s, when less was known about climate change:On the first condition, there is no convincing evidence of which I am aware that the effects of CO2 are known to be highly nonlinear. Possible exceptions are the melting of the Arctic sea-ice pack and disintegration of the West Antarctic ice sheet. These would surely have highly nonlinear effects, but (particularly for the second) we do not have clear ex-ante knowledge of where (or when) the nonlinearity will arise. Put differently, if our ex-ante (or judgmental) probability of such discontinuous events is smooth, then from a decision-maker's perspective the expected consequences are not highly non-linear and the presence of uncertainly probably does not change the best guess strategy markedly.