Evidence That Standard Models Understate Climate Change’s Impact on the Poor


As clowns like Representative Todd Akin (R-MO) are wont to point out, the scale of the average temperature shift associated with catastrophic climate change is not especially large relative to ordinary fluctuations in the weather. In other words, in most parts of the world summer is much hotter than winter, and the summer-winter gap exceeds the sort of changes associated with carbon emissions. If you’re dumb, this becomes a reason to get blasé about climate change. If you understand the issue, you understand that even modest structural shifts in the climate can have enormous impacts—shifting rainfall patterns, altering sea levels, massively increasing the odds of extreme weather, etc.

Consequently, most climate change analysis focuses on these kinds of problems. But new research from Melissa Dell, Benjamin Jones, and Benjamin Olken gives reason to believe that the hot weather on its own will likely have large adverse consequences for economic growth rates in poor countries:

We find that higher temperatures reduce the growth rate in poor countries, not simply the level of output. Since even small growth effects have large consequences over time, these growth effects – if they persist in the medium run – imply very large impacts of permanent temperature increases. […]

To the extent that responses to future climate change are similar to historical responses, our findings have implications for quantifying potential future impacts of climate change. Even assuming that countries adapt fully after only a decade to temperature changes, if the future response follows our historically-driven estimates, the future effects of climate change for poor countries would be substantially more negative than those implied by existing models. For example, our estimates imply that global climate change would lower the median poor country’s growth rate by 0.6 percentage points each year from now until 2099. Extrapolated over 90 years, the median poor country would then be about 40% poorer in 2099 than it would have been in the absence of climate change.

That’s the estimated negative impact assuming complete and successful adaptation . And that, in turn, is a completely heroic assumption. Members of congress considering the Waxman-Markey bill should think that over, but so should political leaders in China, India, and Brazil.

All this via Ryan Avent.