Cost of Saving the Climate Meets Real-World Hurdles

Analysts say it is hard, given the scientific and philosophical questions that come with the field, to judge the players in the offset markets. But, in recent months, some researchers have begun to single out certain vendors for praise or criticism.

One offset seller winning praise has been NativeEnergy, a Vermont company that offers customers the chance to fund projects being developed. Yesterday, for instance, its Web site said offset funds could help build a wind farm on the Rosebud Sioux Indian reservation in South Dakota. This way, the company says, donors can be sure that their offset funds helped create something.

Caroline Kenney, a special education assistant from Arlington, bought offsets from TerraPass on Earth Day last year. She said it took care of one climate-unfriendly aspect of her life that she couldn't change.

"I have never been able to find a way to get to my job without using my car," she said. So she offset it, for about $50.

Some offset-sellers have been controversial. One is Planktos, a California company that says it can pump up ocean plant life known as phytoplankton -- which absorbs carbon dioxide -- by scattering iron particles on the surface of the Pacific. Although scientists have said they doubt the plan will have the desired impact, Planktos officials say that it is built on solid science.

Even TerraPass, the offset provider to the Academy Awards and one of the best-known vendors, has been criticized for relying partially on problematic renewable energy certificates.

Tom Arnold, chief environmental officer for the San Francisco-based company, said TerraPass is doing the best it can but has been hampered by a lack of agreement about what an "offset" is supposed to mean.

"The real problem is that there is not even a consensus among environmental groups" about how to define a worthwhile project, Arnold said. "Companies like TerraPass are kind of stuck in the middle."

Analysts also have concerns about the methods used by Carbonfund.org, the Silver Spring nonprofit. It was founded by a former Environmental Protection Agency official, with the goal of providing low-cost offsets -- at $5.50 per ton, they cost less than half the price of NativeEnergy's.

One example: Carbonfund.org donated $16,249 to the National Arbor Day Foundation, which promised to plant trees in U.S. national forests. But officials at the foundation said it would be difficult to know exactly how much carbon the trees, $1 each, would offset.

"You cannot say, 'We can nail it down to the exact pound of CO{-2},' " said Kevin Sander, the foundation's director of corporate partnerships.

Carlson, Carbonfund.org's executive director, said his organization estimated the offset value of the trees, using what he said are common industry standards. He said the group actually purchased more trees than the models showed were needed.