According to AP, via Forbes, California would become the first state to impose a limit on all greenhouse gas emissions, including those from industrial sites, under a groundbreaking deal reached by Gov. Arnold Schwarzenegger and legislative Democrats.

The agreement marks a clear break with Bush administration policy and puts California on a path to reducing its emissions of carbon dioxide and other greenhouse gases by an estimated 25 percent by 2020. If passed, a key mechanism driving the reductions would be a market program allowing corporations to buy, sell and trade emission credits with others.

The nation’s most populous state is the world’s 12th-largest emitter of greenhouse gases and could suffer dire consequences if global temperatures increase only a few degrees. Reports by state agencies indicate that a 2- to 3-degree rise in temperature could melt the Sierra Nevada snowpack earlier each year, leading to flooding in the Central Valley and threatening the state’s long-term water supply for cities and farms.