Global warming is one of our toughest environmental challenges, threatening the health of people, wildlife and economies around the world. We have the know-how to start fixing the problem, but we have to start soon. Decisions we make today will affect the planet for years to come.

The problem is carbon dioxide and other heat-trapping pollution -- mainly from cars, power plants and other industrial sources that burn gasoline, coal and other fossil fuels -- collecting like a blanket in the atmosphere. As a result, the planet is getting warmer. In fact, 2002 was the second warmest year on record, according to NASA (right behind 1998, and just ahead of 2001).

Although earth temperatures fluctuate naturally, warming over the past 50 years is the fastest in history. And experts think the trend is accelerating. Scientists say that unless global warming emissions are reduced, average U.S. temperatures could be 3 to 9 degrees higher by the end of the century.

It's not just about shorts and sandals. Global warming means more air pollution and problems with water supplies as precipitation patterns change, as well as huge threats to ecosystems from the Everglades to the glaciers. There will be hotter, longer heat waves and more intense storm systems. Forests, farms and cities will face troublesome new pests and more mosquito-borne diseases. Scientists say many of these symptoms are already appearing.

The good news is that the solutions to this problem are clear. The technologies to build cleaner cars and to modernize power plants are readily at hand. We can lean more heavily on renewable energy sources such as wind, sun and hydrogen fuel cells. And we know how to make more efficient appliances and to conserve energy at home, in the office and on the road.

The United States has long been the world's leading developer of new technologies. But we are also the leading global warming polluter: with only 4 percent of the world's population, we produce 25 percent of the carbon dioxide pollution. We have a responsibility, as individuals and as a nation, to lead the world toward slashing emissions of carbon dioxide and other heat-trapping gases. And we have the solutions to this problem -- but we have to begin using them now.

Clean Energy Solutions Power plants are the largest U.S. source of global warming pollution, producing 2.5 billion tons of heat-trapping pollution every year. But we can meet our energy needs without all the pollution. Most of our electricity comes from decades-old, dirty coal-burning power plants -- these dinosaurs can be phased out and replaced with cleaner plants. Relying more on renewable energy sources, such as wind, solar power and hydrogen fuel cells, would dramatically reduce global warming pollution. California has required its largest utilities to get 20 percent of their electricity from renewable sources within 15 years; other states could do the same. We can make our homes, offices and industries much more energy-efficient, which would cut pollution and save money. Each time you choose a compact fluorescent light bulb over an incandescent bulb, you'll lower your energy bill and keep half a ton of carbon dioxide out of the air. Clean Car Solutions Automobiles are the second-largest U.S. source of heat-trapping pollution, pumping 1.4 billions tons into the atmosphere each year. But cost-effective technologies are already available that would reduce global warming pollution from cars and light trucks of all sizes. Hybrid gas-electric engines can cut global warming pollution by one-third or more; Honda and Toyota have hybrid models on the market today, and wagon, minivan and SUV models will be available within a year or two from a number of automakers. Automakers have the technology right now to raise fuel economy standards for new cars and light trucks to a combined 40 mpg. Automakers have used a legal loophole to make SUVs far less fuel efficient than they could be; the explosive sales of these vehicles has propelled a 20 percent increase in transportation-related carbon dioxide pollution over the last decade. Closing this loophole and requiring SUVs, minivans and pick-up trucks to be as efficient as cars would yield savings of 120 million tons a year by 2010.

last revised 1.31.03