A look at Senate global warming bill

Global warming legislation approved Wednesday by the Senate Environment and Public Works Committee would:

_ Require carbon dioxide and other so-called greenhouse gas emissions reduced by 20 percent from 2005 levels by 2020, and 70 percent by 2050.

_ Cover electric power, manufacturing and transportation, which accounts for 80 percent of U.S. economy-related greenhouse gas emissions.

_ Allow trading of emission allowances, a "cap-and-trade" system. Companies unable to meet their emission cap could buy allowances from other companies that have exceeded their required cuts.

The bill, which was approved 11-8, represents the first action by Congress to advance mandatory greenhouse gas emission reductions since global warming emerged as an environmental issue in the 1980s.

Senate leaders plan to take up the legislation next year but prospects of passage are uncertain. The House has yet to take up climate change legislation.