SACRAMENTO, Calif., and SEATTLE - A number of states and cities have committed to reducing their greenhouse gas emissions in recent weeks. Most notable is California, where Governor Arnold Schwarzenegger has issued an executive order setting a number of greenhouse gas targets.

Under the California executive order, the state will aim to cut greenhouse gas emissions to 2000 levels by 2010, to 1990 levels by 2020, and to 80 percent below 1990 levels by 2050. Meeting those goals will be a challenge, since a recent report from the California Energy Commission (CEC) notes that if current trends continue, the state's greenhouse gas emissions will grow to 32 percent above 1990 levels by 2020.

Mayors of U.S. cities are also getting into the act, as the U.S. Council of Mayors endorsed an effort by Seattle Mayor Greg Nickels to challenge cities to meet or beat the requirements of the Kyoto Protocol: cutting emissions to 7 percent below 1990 levels by 2012. Before the meeting of the council, 164 cities had signed on to the challenge. Portland, Ore., has the largest head start. City officials announced in June that Portland has reduced its greenhouse gas emissions to 1990 levels. Portland officials credit the city's investments in public transit, energy efficiency, renewable energy, green building technologies, and recycling.