Thursday, August 6, 2009

Immigration and climate change

Tree Hugger has posted about an interesting idea: immigration actually causes more pollution.

The argument here is that immigration and population growth are not zero sum. When people move to another country, they do so because it offers better opportunities. With those better opportunities comes the possibility of having a larger family, and so world population will increase more than if the people had stayed home. This is then followed by a graph suggesting that the US population would be less than half what it is now if there had been no immigration since the founding of the country.

I have two problems with this argument. The first is that population growth is actually higher in developing countries. This happens for a number of reasons, but the relationship is clear. So, while we may think that moving to the US means you have a better opportunity to have a large family, after only one or two generations that effect is reversed.

Second, Tree Hugger is making the mistake of looking at the average effect of an American. A new immigrant probably does not consume as much meat, drive a car as much, or buy as much stuff in general that the average American does, at least for the first few generations. So, the impact of an immigrant is actually much smaller than this might suggest.

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