(08-22) 12:04 PDT SACRAMENTO -- A coalition of six Western states and two Canadian provinces will announce this afternoon that they have set a regional goal to fight global warming - a goal similar to last year's California legislation to cut greenhouse gas emissions.

Six months ago, governors in Arizona, California, New Mexico, Oregon and Washington signed an agreement to create the Western Climate Initiative partnership to improve the environment by reducing carbon emissions. Since then, Utah and Canadian provinces Manitoba and British Columbia have also joined the effort.

The partners today will announce that they have set a goal to reduce the region's greenhouse gas emissions about 25 percent by 2020, which is similar to California's AB32 legislation that passed with much fanfare.

The region's new standard was based on some existing goals that the states and provinces have set to reduce their emissions, said Sarah Cottrell, energy and environmental policy adviser to Gov. Bill Richardson in New Mexico.

The partnership also plans to later create a blueprint for the so-called "cap-and-trade" system in the region, a proposal that would allow high-polluting businesses to buy carbon credits from low-polluting firms in other states and the provinces.

Gov. Arnold Schwarzenegger and business organizations have championed such a system for California, although Democratic lawmakers and environmentalists have argued that AB32 requires regulations to cut emissions before considering such market-based systems of trading carbon credits.

It is not yet clear exactly what measures will be taken to reduce greenhouse gases in other states or California. Some of the governments involved in today's decision still must pass laws to establish long-term or short-term reduction goals for the gases like carbon dioxide and methane.