Commentary: Can carbon credits save the rainforest?

California, a global leader on climate change, is poised to take the lead once again as it considers expanding its carbon offset program to allow polluting companies to compensate for their excess emissions by paying to preserve the Amazon rainforest.

That sounds like a winning proposition: The carbon preserved in trees spared from deforestation would cancel out the corresponding amount of pollution from, say, refineries. But as I found on a recent trip