Accounting for about 7 percent of total U.S greenhouse gas emissions, California passed an aggressive anti-global-warming law last year that calls for reducing those emissions 25 percent by 2020. To prove that reductions are actually taking place, the state is funding a pilot program that will rely on sensors atop two towers in northern California to continuously measure a suite of greenhouse gases, including carbon dioxide and methane. The sensors will wire data back once a day to be inspected and analyzed. This is the first time a state has monitored greenhouse gases from a mixture of urban, suburban and rural areas in a systemic fashion--one tower is in San Francisco and the other is in Walnut Grove, which has a population of about 700. The project, funded through the state Energy Commission's Public Interest Energy Research Program and overseen by the Lawrence Berkeley National Laboratory, is also part of a larger experiment run by the National Oceanic and Atmospheric Administration to determine, among other things, how much of the greenhouse gases are coming from outside California. NOAA has five other such towers in Wisconsin, Maine, Texas, Colorado and Iowa. If the California Greenhouse Gas Emissions Project, or CALGEM, goes well, the state will extend it into Southern Calfornia. To learn more, call PIER at 916-654-4878.