Gremlins intervened in the preparation of my paper “The Economic Effects of Climate Change” . . . minus signs were dropped from the two impact estimates . . . [also there were] two overlooked estimates . . .
Although the numbers have changed, the conclusions have not. The difference between the new and old results is not statistically significant. There is no qualitative change either.
The assessment of the impacts of profound climate change has been revised: We are now less pessimistic than we used to be.
The original impact curve projects an impact of −15 (−7 to −33) percent of income for a 5°C warming, whereas the corrected and updated curve has −6 (−3 to −21) percent. This is relevant because the benefits of climate policy are correspondingly revised downwards.
Given that the studies in Table 1 use different methods, it is striking that the estimates are in broad agreement on a number of points—indeed, the uncertainty analysis displayed in Figure 1 reveals that no estimate is an obvious outlier.
The fitted line in Figure 1 suggests that the turning point in terms of economic benefits occurs at about 1.1 degrees Celsius warming (with a standard deviation of 0.7 degrees Celsius).