The Sierra Club is backing Obama.

According to Carl Pope, the Sierra Club executive director, Obama supports the “strongest set of positions that any candidate has ever offered” on the environment.

Mr. Obama favors a cap and trade system aimed at reducing carbon dioxide emissions in the United States to 80 percent below 1990 levels by 2050. He has also called for 25 percent of electricity to come from renewable energy sources by 2025.

(Source: New York Times via Obama Campaign blog)