Roughly a third of America's emissions of the carbon dioxide that causes climate change comes from cars and trucks. The technology exists today to dramatically reduce these emissions and, with a little research, even greater reductions could be achieved.

The leaders of the U.S. auto industry don't want to do that. They are much happier continuing to sell gas guzzlers while American men and women die in foreign lands to protect our oil supplies in the Middle East, while Saudi oil millionaires slip money to terrorist groups, and while a motor-mouth populist in Venezuela uses oil revenues to promote anti-American activities across Latin America.

Early in President Bush's first term the American people were deceived with the mirage of hydrogen vehicles that soon would make automobiles pollution-free. Perhaps by late this century they will. In the meantime, the promise of a perfect hydrogen future was used as a smoke screen to help the auto industry avoid implementing the many fuel- and energy-saving technologies that are on the shelf today.

Under the leadership of its Republican governor, California decided it was time to stop stalling and get on with cleaning up the vehicles sold within its borders. While California is taking the lead, Pennsylvania, New York, New Jersey, Massachusetts and eight other states plan to adopt any new tighter standard that California develops, as they have in the past. Governors in four additional states say they propose to do the same. These 17 states make up roughly half of the U.S. market for automobiles.

In addition to tighter mileage standards, California has been developing a low-carbon fuel standard that will encourage a wide variety of innovative activities. Examples include ethanol made from cellulose (wood and grass, not corn and other food crops) and hybrid electric vehicles that can be plugged in at night and charged with power from wind and other sources that do not emit carbon dioxide. These vehicles would make possible emissions-free commuting.

Congress has finally gotten the message. Last week, for the first time in 22 years, it voted to tighten CAFE, the federal fuel-economy standards for auto makers. Seeing the writing on the bipartisan wall, President Bush signed the bill. But the timeline this bill lays out is slower, and the reduction targets lower, than what California, Pennsylvania and 15 other states already plan to achieve.

Late last Wednesday, after all the evening television news shows had signed off, Environmental Protection Agency Administrator Stephen Johnson announced that, contrary to the advice of much of his staff, he was going to block California's effort to tighten its auto-emissions standards.

California has always led the nation in setting tough standards, which have then spread across the country. The only requirement has been that the state ask the EPA for approval -- which in the past has always been granted. But in what appears to be an effort by the administration to help the U.S. auto industry do as little as possible as late as possible, Mr. Johnson argued that he was turning down California's proposals in order to avoid a "confusing patchwork of state rules."

Baloney! Under the terms of the Clean Air Act there are only two rules, the EPA rules and the more stringent California rules. States adopt one or the other. By attempting to block California's proposal, the Bush administration is abandoning any pretense of global leadership by refusing to provide incentives for U.S. inventors and industry to develop products that will better compete in the global marketplace.

With the mirage of hydrogen faded and Congress moving to tighten fuel-economy standards, this decision by the administration is simply an effort to make sure that any progress we make in de-carbonizing the U.S. auto fleet and overcoming our addiction to foreign oil will take as long as possible.

California already has announced that it will appeal the EPA decision; Pennsylvania and other states plan to join the effort.

The smart money is on the EPA decision being overturned -- the administration and the auto industry already have lost three major court cases on carbon-dioxide and motor-vehicle regulations this year. But lawsuits take time, so Mr. Johnson has bought the administration's friends in the oil and auto industries a few more years of doing as little as possible.

Meanwhile, you can be confident that foreign manufacturers like Toyota, which years ago saw the need for cleaner cars and hit the market with hybrids while the U.S. industry stalled and talked of hydrogen, will be innovating rapidly so that when the inevitable tightening of fuel-economy standards does occur, they will be ready to compete, further eroding the market strength of the once dominant U.S. auto industry.

If the EPA's decision to block California standards holds up for the next few years, new gas-guzzling American-made cars will continue to emit large amounts of carbon dioxide, which stays in the atmosphere for more than 100 years. Those emissions will accelerate the warming of the climate, melt polar ice and contribute to more frequent droughts, while our oil dependency will continue to fund oppressive regimes in the Middle East, building an even more negative legacy for our grandchildren.