There's no longer any real doubt about it: Global warming is happening. The average temperature of the Earth's surface has risen about 1 degree Fahrenheit over the last hundred years, and overwhelming evidence suggests that most of the increase is due to carbon dioxide released by humans. Though a 1-degree increase might not seem like much, even a small rise in global temperature significantly changes the climate, potentially resulting in major storms and droughts, disruption of the food supply, and the catastrophic spread of disease.
Human carbon dioxide emissions come mainly from two sources: burning fossil fuels and changes in land use, such as deforestation. Americans are the climate's worst enemy. On average, each of us is responsible for about 22 tons of carbon dioxide emissions every year, according to the United Nations, compared with an average of six tons per person throughout the rest of the world. That means that the typical U.S citizen emits the equivalent of 4,000 cars.
Much of the discussion around climate change involves national and international policy—should the United States sign the Kyoto Treaty or increase auto efficiency standards? But even without major political or legislative changes, there's a lot that concerned individuals can do to make the problem better. To that end, we've created the Slate Green Challenge—a straightforward program to evaluate and reduce your carbon emissions between now and the end of the year.
For eight weeks beginning Oct. 23, Slate, in collaboration with the Web site TreeHugger, invites you to consider your own individual contribution to global warming—and challenges you to go on a carbon diet. The goal is to reduce the amount of CO2 that you put into the atmosphere by 20 percent. If you're a carbon fatso who doesn't bother to turn off the lights when you leave the house, you may find this diet pretty painless. (And just think of the fringe benefits—lower heating bills, smoother international relations.) But even if you're already a svelte recycler or a carpooler, there's a lot more you can do. Come back next week and start shedding those carbon pounds!