- Research found that, at the turn of the century, 77 percent of countries will be poorer, in terms of per capita wealth, than they would be in a world without climate change.
- Economic output rises up until a 13°C/55°F threshold, then falls at increasingly faster rates as temperatures rise.
- The researchers say the lesson for negotiators in Paris should be that the more they spend on mitigation now, the less global warming will cost us in the future.
Human productivity peaks at an annual average temperature of 13° Celsius (55° Fahrenheit) and declines sharply the hotter it gets, according to researchers at UC Berkeley and Stanford.
That could lead to growing economic inequality as incomes the world over shrink as much as 23 percent by 2100 in response to global warming — a much higher toll than previous research has suggested, the researchers say. Their findings were summarized in an article published by the journal Nature.
“The data tell us that there are particular temperatures where we humans are really good at producing stuff,” Marshall Burke, a professor of Earth system science at Stanford and a lead author of the Nature article, said in a statement. “In countries that are normally quite cold — mostly wealthy northern countries — higher temperatures are associated with faster economic growth, but only to a point. After that point, growth declines rapidly.”
Many of the impacts of global warming are well understood, but exactly how much rising temperatures will disrupt economic productivity has received less attention, Burke and his co-authors write in the report.
Once average temperatures move beyond the 13°C/55°F comfort zone, even wealthier nations will see economic output begin to lag. But many poorer countries in the tropics are already hotter than that on average, which means they will suffer an even larger drop in productivity, widening the economic gap between rich and poor.
Still, the economic suffering will be fairly widespread. The authors estimate that, by the turn of the century, 77 percent of countries will be poorer, in terms of per capita wealth, than they would be in a world without climate change.
The researchers analyzed data from 166 countries gathered between 1960 to 2010 and compared economic productivity during years with normal temperatures to years that were unusually warm or cool. They found output rose up until the 13°C/55°F threshold, then fell at increasingly faster rates as temperatures rose.
“Many other researchers have projected economic impacts under future climate change,” Solomon Hsiang, a professor of public policy said. “But we feel our results improve our ability to anticipate how societies in coming decades might respond to warming temperatures.”
China, Japan, and the US have average annual temperatures close to optimal, so rising temperatures will only hurt their economies. But Brazil, India, Indonesia and Nigeria are much warmer already, so their economies will take a bigger hit.
Not all countries will fare poorly, at least in the short-term. The UK and Germany, for instance, are cooler than 13°C/55°F, meaning their economies may grow at first, though they’ll start to decline as temperatures continue to rise.
Stanford’s Burke said attendees of the UN climate negotiations taking place in Paris in December — known as COP21 because it is the 21st Congress of Parties to the United Nations Framework Convention on Climate Change — should take note of the study’s results, because they clearly show that the more we spend now to mitigate the impacts of global warming, the less it will cost us in the future.
“Our research is important for COP21 because it suggests that these economic damages could be much larger than current estimates indicate,” Burke said. “What that means for policy is that we should be willing to spend a lot more on mitigation than we would otherwise. The benefits of action on mitigation are much greater than we thought, because the costs of inaction are much greater than we thought.”
The study did not factor in extreme weather events such as droughts or hurricanes, rising sea levels or any other impact of climate change besides rising temperatures — meaning the true economic costs of global warming could be far higher.
Thomas Sterner of Sweden’s University of Gothenburg in Sweden, who was not involved in the report, told the Guardian that we are already experiencing economic impacts due to global warming, such as more frequent heat waves that increase health costs and employee absenteeism while reducing crop yields.
“The conclusion [of the new research] that temperature-associated costs will be higher than previously calculated will cause a stir, and should have stark repercussions for policy,” Sterner said. “My feeling is that we are only beginning to understand just how much damage a changed climate can wreak.”
- Burke, M., Hsiang, S. M., & Miguel, E. (2015). Global non-linear effect of temperature on economic production. Nature 527. 235–239. doi:10.1038/nature15725