Reuters: The chairman of a key committee in the House of Representatives will propose climate change legislation that would cut greenhouse gas emissions at a rate that is somewhat more aggressive than proposals by President Barack Obama, sources said on Monday. The legislation by House Energy and Commerce Committee Chairman Henry Waxman would require that U.S. carbon emissions be reduced by 20 percent from 2005 levels by the year 2020, 42 percent by 2030 and 83 percent by 2050, according to …