Do hot climates create sluggish economies?

Countries with hot climates tend to be the most economically challenged ones. For most of us, the explanations are routed in the world history of slavery and colonialism. But for MIT economics professor Ben Olken, the story may not be that simple. Olken and his colleagues have examined the temperature-income relationship not just between countries but within countries. What did they find? A negative relationship between temperature and income does exist, although it is much weaker than that between countries. A full paper of this work can be found here, and a full report on the NPR website (including an interesting discussion with many interesting suggested explanations).