U.S. Must Meet Global Warming Challenge

Democratic front-runner Hillary Clinton Monday pledged to slash US greenhouse gas emissions, as she aimed to bounce back from her most difficult week yet on the campaign trail.

Clinton's comprehensive plan to tackle global warming represented the latest sign that environmental issues are playing a greater role in the 2008 White House race, than in any previous US election.

"This is the biggest challenge we've faced in a generation, a challenge to our economy, our security, our health, and our planet," Clinton said in the midwestern state of Iowa, which holds first party nominating contests on January 3.

"It is time for America to meet it," she said.

The Clinton plan uses a cap and trade system to reduce greenhouse gas emissions by 80 percent from 1990 levels by 2050, in a bid to head off the most damaging results of global warming.

It also sets a target of reducing foreign oil imports to the gas guzzling United States by two-thirds from levels projected to be reached in 2030 -- a cut of 10 million barrels per day.