"Put it on my carbon tab." (damaging effects of carbon release on the environment)

• Author: Kane, Hal

New people notice it, but an "I.O.U." is attached to each of our paychecks. Accountants don't record it on their ledgers, tax collection agencies don't pursue it, and no bank will honor it. Yet this debt is tabulated each day, a subtle component of the work we do, the entertainment we enjoy, the objects we consume.

What is this pervasive lifestyle tab? It's the carbon dioxide we "spend" each day. The world economy is fueled by burning oil, coal, and gas, which releases almost 6 billion tons of carbon into the atmosphere every year. Initially, that carbon is released free of charge. But if scientists are correct, then the bill for our carbon spending will come due down the road as its environmental repercussions are debited. Climate change caused by unprecedented concentrations of carbon dioxide in the atmosphere will disrupt the world's economy, they say. Sea levels will rise, crop yields will drop, forests will migrate, and energy needs will climb. We will have spent away the security that a balanced atmosphere and stable climate provide.

William Cline, senior fellow at the Institute for International Economics in Washington, D.C., estimates those future costs, for the U.S. economy alone, at about $60 billion a year toward the middle of the next century if the atmospheric levels of carbon dioxide double, and at about $335 billion a year in the distant future, assuming temperature continues to rise. That is a bigger bill than most people expect when they are sitting in their cars in five o'clock rush-hour traffic.

On average, for every $3.19 of world economic output, one kilogram (2.2 pounds) of carbon is released into the air. That means the average person sends the equivalent of his or her body weight of carbon into the atmosphere for about every $200 that he or she spends.

All the clothes that we wear, the food we eat, and the houses we live in are made with processes that burn energy. When we look at those components of our lives, we may not see the energy that goes into them, but it is there in their manufacture, transport, maintenance, marketing, use, and disposal.

Of course, the amount of carbon people "emit" varies, usually depending on where they live. Though it contains less than 5 percent of the world's population, the United States emits 22 percent of all carbon. All developing countries together - which account for almost 80 percent of the world's population - produce not much more than that. The average American sends 15,000...