Burke, Marshall, Solomon Hsiang, and Edward Miguel. 2015. "Global non-linear effect of temperature on economic production", Nature, doi:10.1038/nature15725.

We show that overall economic productivity is nonlinear in temperature for all countries, with productivity peaking at an annual average temperature of 13 C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change.