Today's New York Times looks into the debate over carbon offsets, and questions whether claims of "carbon-neutrality" are just a "gimmick."

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. . . .

"The worst of the carbon-offset programs resemble the Catholic Church's sale of indulgences back before the Reformation," said Denis Hayes, the president of the Bullitt Foundation, an environmental grant-making group. "Instead of reducing their carbon footprints, people take private jets and stretch limos, and then think they can buy an indulgence to forgive their sins."

"This whole game is badly in need of a modern Martin Luther," Mr. Hayes added.

Some environmental campaigners defend this marketplace as a legitimate, if imperfect, way to support an environmental ethic and political movement, even if the numbers don't all add up.