From the NYT:

THE rush to go on a carbon diet, even if by proxy, is in overdrive.

In addition to the celebrities — Leo, Brad, George — politicians like John Edwards and Hillary Clinton are now running, at least part of the time, carbon-neutral campaigns. A lengthening list of big businesses — international banks, London’s taxi fleet, luxury airlines — also claim “carbon neutrality.” Silverjet, a plush new trans-Atlantic carrier, bills itself as the first fully carbon-neutral airline. It puts about $28 of each round-trip ticket into a fund for global projects that, in theory, squelch as much carbon dioxide as the airline generates — about 1.2 tons per passenger, the airline says.

Also, a largely unregulated carbon-cutting business has sprung up. In this market, consultants or companies estimate a person’s or company’s output of greenhouse gases. Then, these businesses sell “offsets,” which pay for projects elsewhere that void or sop up an equal amount of emissions — say, by planting trees or, as one new company proposes, fertilizing the ocean so algae can pull the gas out of the air. Recent counts by Business Week magazine and several environmental watchdog groups tally the trade in offsets at more than $100 million a year and growing blazingly fast.

But is the carbon-neutral movement just a gimmick?

On this, environmentalists aren’t neutral, and they don’t agree. Some believe it helps build support, but others argue that these purchases don’t accomplish anything meaningful — other than giving someone a slightly better feeling (or greener reputation) after buying a 6,000-square-foot house or passing the million-mile mark in a frequent-flier program. In fact, to many environmentalists, the carbon-neutral campaign is a sign of the times — easy on the sacrifice and big on the consumerism.