FACTBOX-Comparison of regional U.S. carbon plans

(Reuters) - U.S. states who have led their country in setting limits on emissions of the gases most scientists blame for global warming are keeping up the pressure even as a federal plan to address climate change takes shape.

President Barack Obama wants to cut emissions of greenhouse gases to 1990 levels by 2020 and 80 percent from there by 2050. Leaders in Congress hope to put forth a bill later this year.

In the East, the Regional Greenhouse Gas Initiative has already started regulating carbon dioxide emissions from power plants.

On the opposite coast, the Western Climate Initiative hopes to start regulating six greenhouse gases across the entire economy with tougher caps starting in 2012.

Below is a comparison of how the Eastern and Western states plan to cut emissions.

Plan RGGI (East) WCI (West)

Emissions covered CO2 six gases including CO2,

methane, and sulfur

hexaflouride

States 10 in the East 7 in the West led by Calif. and

Led by NY 4 Canadian provinces

Effective date 2009 2012 for power plants and

industry. 2015 for

transportation

Number of regulated 233 power plants To be determined

polluters

Emissions cap level 10 pct reduction 15 pct reduction by 2020

by 2018 below 2009 below 2005 levels

levels

Distribution of About 90 pct min 10 pct auction by 2014

permits auctioned min 25 pct auction after 2020

Offsets Limited to 3.3 pct No more than 49 pct of

of a generator's total emission reductions

total emissions from 2012 to 2020

-Sources: Environment Northeast, states.

(Reporting by Timothy Gardner; Editing by David Gregorio)