Increased temperatures from climate warming will hurt poor countries and limit their long-term growth, a U.S. researcher says. Ben Olken, a professor of economics at MIT who co-authored the study, said every 1-degree-Celsius increase in a poor country over the course of a given year reduces its economic growth by about 1.3 percentage points. And it\'s not just droughts and hot weather hurting agriculture, he said; hot spells have much wider economic effects. \"What we\'re suggesting is that it\'s much broader than [agriculture],\" Olken said. \"It affects investment, political stability and industrial output.\" The study looked at temperature and economic-output data for each country in the world, in every year from 1950 through 2003, looking at economic data by type of activity, an MIT release reported Tuesday. There are a variety of \"channels\" through which weather shocks hurt economic production, the researchers found, by slowing down workers, commerce, and perhaps even capital investment. \"If you think about people working in factories on a 105-degree day with no air conditioning, you can see how it makes a difference,\" Olken said. The researchers said their findings apply only to the world\'s developing nations, as wealthier countries do not appear to be affected by the variations in temperature. \"The impacts of these things are going to be worse for the countries that have the least ability to adapt to it,\" Olken said. \"[We] want to think that through for the implications for future inequality. It\'s a double whammy.\"