Proposals to combat global warming are suddenly cropping up faster than ice melts on a summer day:

Republican Gov. Arnold Schwarzenegger signed the nation's first cap on temperature-raising greenhouse gases last month in California. He initiated an ambitious schedule of emissions cuts by power plants, factories and cars by 2020.

Former Vice President Al Gore is proposing "green" mortgage incentives and electricity buy-backs to chip away at the "inconvenient truth" he believes is on an escalating trajectory.

Even the Bush administration has the new 244-page "Climate Change Technology Program Strategic Plan," although it's too heavy on the usual cop-out solutions — more research and voluntary industry efforts.

The trend is in the right direction, but a wrong U.S. Supreme Court decision this term could put a chill on climate policies nationwide.

In one of the most important environmental cases ever to come before the court, justices will decide whether the Environmental Protection Agency has the authority to regulate greenhouse gases that contribute to global warming.

Massachusetts v. EPA challenges the agency's refusal to enforce a section of the Clean Air Act on pollutants that affect weather and the climate and have an adverse effect on public welfare.

The court's decision, expected several months after the scheduled Nov. 29 arguments, could hasten U.S. mitigation of greenhouse-gas emissions — or bring action to a disappointing halt. Under the court's microscope are California's efforts to regulate vehicle tailpipe emissions, adopted by 11 other states.

The ruling will reveal more about the ideological leanings of Chief Justice John Roberts' court, as will pivotal cases on race and abortion this term. Depending on how the decision goes, it could have enormous repercussions about standing in future environmental cases.

The case already has created unusual bedfellows. Entergy Corp., for example, a power company based in New Orleans, is siding with climatologists and environmentalists, because it seeks regulatory certainty. The patchwork of regulations emerging as California, Northeastern states and Europe all take slightly different approaches to global warming makes planning 25-year capital investments difficult.

Forward-looking utilities know science doesn't support the federal government's current aversion to regulating carbon emissions. Rules that come sooner will help companies build cleaner plants now that won't need expensive retrofits later.

Congress could end this protracted and expensive legal debate over the applicability of the Clean Air Act by passing legislation specific to global warming. Instead, key committee leaders have wasted years vilifying respected scientists, second-guessing peer-reviewed studies and calling novelists as expert witnesses. It's no wonder states set out on their own.

The United States needs to catch up to the rest of the world and, as a nation, work to reduce the human contribution to global warming.