Via LA Times:

For environmentalists, population has long been a problem. Many of the things we do wouldn’t cause so much trouble if there weren’t so many of us. It’s why I wrote a book some years ago called “Maybe One: An Argument for Smaller Families.” Heck, it’s why I had only one child.

And many of us, I think, long viewed immigration through the lens of population; it was another part of the math problem. I’ve always thought we could afford historical levels of immigration, but I understood why some other environmentalists wanted tougher restrictions. More Americans would mean more people making use of the same piece of land, a piece that was already pretty hard-used.

In recent years, though, the math problem has come to look very different to me. It’s one reason I feel it’s urgent that we get real immigration reform, allowing millions to step out of the shadows and on to a broad path toward citizenship. It will help, not hurt, our environmental efforts, and potentially in deep and powerful ways.

One thing that’s changed is the nature of the ecological problem. Now that global warming is arguably the greatest danger we face, it matters a lot less where people live. Carbon dioxide mixes easily in the atmosphere. It makes no difference whether it comes from Puerto Vallarta or Portland.

It’s true that the typical person from a developing nation would produce more carbon once she adopted an American lifestyle, but she also probably would have fewer children. A December report from the Pew Research Center report showed that birthrates in the U.S. were dropping faster among Mexican American women and women who immigrated from Mexico than among any other group.