Environment / Global Warming

Of course, it’s too easy (but nonetheless fair) to pick on SUVs. I drive a Volvo V70 Cross Country station wagon, a favorite of exurban environmentalists. My car annually produces 26,000 pounds of greenhouse-gas emissions—more than two killer whales’ worth of pollution. If I switched to a lightweight SUV like the Ford Escape hybrid, I could cut my greenhouse-gas emissions to 18,000 pounds. But with a lighter hybrid, like a Toyota Prius sedan, I could get down to 10,000 pounds.

But the truth is that a lot of American families, mine among them, can’t afford to replace their cars right now. “That’s OK,” says Jim Kliesch of the American Council for an Energy-Efficient Economy, the nonprofit behind www.greenercars.com. The idea is simply to get people thinking about environmental consequences next time they buy a car. Even stepping up from the Volvo V70 to a car that gets an extra two miles a gallon avoids about a ton of greenhouse-gas emissions annually. By neglecting to think about such things, Kliesch says, we get locked into purchases we could regret for years, or generations, to come.

GREEN +Honda Insight +Toyota Prius +Honda Civic Hybrid +VW Jetta Diesel +Honda Civic +Toyota Echo +Toyota Scion XA MEAN +Ford Excursion +Hummer H2 +GMC Yukon XL K2500 +Chevrolet Suburban K2500 +Land Rover Range Rover

For a lot of people and organizations feeling stuck on the wrong side of the global-warming balance sheet, one solution is to offset the emissions they cannot eliminate. In essence, they pay somebody else not to pollute, or they pay for activities like planting trees that are assumed to remove carbon dioxide from the atmosphere. As a practical alternative for individual consumers, the retail market in emissions offsets is promising—but not yet ready for prime time.

Most trading in carbon dioxide offsets now occurs only on a large scale. It works like this: One company installs new equipment to cut its emissions by 5,000 tons. Then it sells the right to emit 5,000 tons to a buyer for whom new equipment would be too costly. To avoid simply swapping pollution from one place to another, these so-called cap-and-trade systems usually involve a gradual, government-ordered reduction in overall emissions. As the cheaper reductions get put into place, participants move on to the more difficult reductions, and the trades become steadily more pricey. Selling emissions rights helps defray the cost of making reductions.

To some people, reforestation projects, like the ones the Rolling Stones arranged, seem like the most appealing way to offset emissions. In one case, a power company paid $13.7 million to reforest 100,000 acres of U.S. Fish and Wildlife Service land in Mississippi in the expectation that every acre of trees would absorb enough carbon dioxide to offset 150 tons of greenhouse-gas emissions over the life span of the trees. But critics say such these schemes are much less effective than advertised.

“Basically, they’re selling a warm, fuzzy feeling,” says Dennis King, a University of Maryland researcher and the author of an EPA-funded study of carbon sequestration. Young trees don’t actually start to sequester significant amounts of carbon dioxide for 20 years, he says, and it takes a tree 100 years to remove a measly 3,000 pounds of carbon dioxide from the atmosphere—assuming the tree survives drought, fire, flood, disease, and other afflictions. But, King says, the buyer “gets to dump a ton of carbon into the atmosphere with 100 percent certainty” today. Moreover, most of the carbon that gets sequestered in these forestry projects will eventually be released again when the trees die and decompose—or get harvested. “The numbers don’t look good when you work them out,” King says.

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The danger of such projects is that they risk discrediting the market in greenhouse-gas emissions just as it is starting to get off the ground. One Swiss multinational, the Holcim Group, recently pulled out of a mitigation scheme, with an executive predicting that loose accounting standards will produce “other Enrons” among the companies developing such projects and “other Arthur Andersens” among the auditors.

Proponents of offsets are acutely aware of the need to protect the credibility of their burgeoning market. The Chicago Climate Exchange, the leading marketplace, started trading carbon dioxide emissions in 2003, with members like IBM and International Paper committing themselves to a voluntary schedule of reductions. Exchange chairman Richard Sandor says it uses the National Association of Securities Dealers to audit its transactions. A company that fails to deliver on emissions-reduction claims, he says, can expect to be treated the same as a company that overstates its earnings. This is a polite way of saying that CEOs could end up in court and their company stock in the doghouse.

But determining what is a legitimate way to reduce greenhouse-gas emissions—and how to account for it—is going to be a long, messy process. Moreover, the scale of the problem is unlike anything previously attempted. For instance, Statoil, the Norwegian energy company, has engineered a drilling platform in the North Sea to pump a million tons of carbon dioxide back underground every year. Construction alone cost $100 million. Geologists believe that it is a permanent way to keep carbon dioxide out of the atmosphere.

The problem, says climate scientist Ken Caldeira of Lawrence Livermore National Laboratory, is that even assuming a modest attack on global warming, “we would need to build one of these a day for the next 50 years to maybe get halfway there.”

A FOOL’S FORMULA Carbon dioxide makes up more than 80 percent of greenhouse gases that cause global warming. The rest is composed of methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride released by burning fossil fuels.

So where does this leave my family and yours as we roll down the highway trailing our vast burden of greenhouse-gas emissions? Individuals can also buy offsets to compensate for the things we haven’t yet figured out how to reduce. But how many? A shortcut is to take the share of greenhouse-gas emissions under the average American’s individual control—call it 10 tons, for simplicity—and multiply that by the number of people in the household. For my family of five, I would need 50 tons of offsets a year.

You can get your offsets wholesale at about $1.30 a ton. An individual can register with the Chicago Climate Exchange as an exchange participant for a onetime fee of $250, then contact a broker to place an order. The typical minimum order is 2,500 tons. But Amerex, a Houston brokerage, says it will take smaller orders, with a base commission of $150. The hitch for me is that trades on the Chicago Climate Exchange are anonymous, and buyers do not know what kind of offset projects they have purchased until after a transaction is complete. So you can get stuck with offsets involving reforestation projects.

The gold standard in offsets are the ones that pay other people to use less fossil fuels—the only way to get at the root of the global-warming problem. Several services come close to fitting the bill. The Better World Club, an environmentally oriented alternative to AAA, sells offsets to help people “travel guilt free.” But it has donated money for only one project so far, a $13,000 replacement of inefficient oil-burning furnaces in public schools in Portland, Oregon. TerraPass, a start-up by students at the University of Pennsylvania’s Wharton School, offsets emissions by investing in wind power and reduction of methane emissions in agriculture. But it’s also small.

I ended up at the Solar Electric Light Fund, a nonprofit that installs hundreds of solar photovoltaic systems a year in developing countries. According to www.self.org, a $100 donation prevents 10 tons of greenhouse-gas emissions from kerosene lanterns and diesel generators in places like Bhutan and Tanzania—and it’s tax deductible.

I went to bed thinking that, for $500, I had at last made my household carbon neutral. But in the middle of the night I woke up from a dream in which Inuits balanced on a vast mathematical and moral equation made of ice, which was rapidly melting. I lay there in the dark, listening to the sound of warm air rushing through the heating ducts.

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JUST PLANT A FEW TREES, RIGHT?

Trees draw carbon dioxide out of the atmosphere through photosynthesis, so one potential way to offset some greenhouse-gas emissions is to plant more forests. But most trees don’t sequester significant amounts of carbon during the first few years after planting. Moreover, when trees succumb to forest fires or begin to decay, they release carbon back into the atmosphere. An acre of fast-growing softwood trees, such as pines, can take in as much as 5 tons of carbon dioxide a year as they enter their peak years of growth at around age 15. Hardwood trees grow more slowly but tend to keep their carbon locked away longer. An acre of walnut trees, for example, can take in as much as 2.2 tons of carbon dioxide a year as the trees enter their peak years of growth at around age 25. The graphic below gives a rough indication of how many walnut trees would have to be planted—and allowed to mature for at least 25 years—to offset the carbon emissions of a typical family of four and the nation at large from just one year.