Climate and the Emergence of Global Income Differences

The latitude gradient in comparative development is a striking fact: as one moves away from the equator, economic activity rises. While this regularity is well known, it is not well understood. Perhaps the strongest correlate of ( absolute) latitude is the intensity of ultraviolet radiation (UV-R), which epidemiological research has shown to be a cause of a wide range of diseases. We establish that UV-R is strongly and negatively correlated with economic activity, both across and within countries. We propose and test a mechanism that links UV-R to current income differences via the impact of disease ecology on the timing of the take-off to sustained growth.