A new paper in Nature looks at the macroeconomic damages of rising temperatures, and its authors—Marshall Burke, Solomon Hsiang, and Edward Miguel—hail from Stanford University and University of California, Berkeley. Hsiang co-directs the Lab. They looked at economic data from 1960 to 2010 in 166 countries, and found that a nation’s productivity declined as its climate got hotter. The researchers’ model found that national productivity increases as temperature goes up, but peaks at an annual average of 55ºF. At higher annual average temperatures than that, a country’s productivity starts declining. They concluded that by the year 2100, 77 percent of countries will be poorer as a result of this lost productivity —with poor countries in hot regions getting hit the hardest.