Al Gore buys them. So do the Grateful Dead, Hollywood celebrities and, increasingly, many climate-conscious executives and consumers.

For those who travel the world by air but don't want to contribute to global warming in the process, compensating with so-called carbon offsets has become a fashionable solution.

The sale of these credits for environmentally friendly activities, investments in everything from wind energy to carbon stored in forests, jumped from $97 million in 2006 to $331 million worldwide in 2007 – about a quarter of it in the United States.

But one global green leader does not offset its travel, even though its employees regularly fly around the world warning about the dangers of climate change and devising strategies to combat it. That leader is the state of California.

"As a state employee, you are put in an awkward situation," said Tony Brunello, deputy secretary of climate change and energy at the Natural Resources Agency who has traveled to Europe, South America and Indonesia.

"We are trying to push (emissions) reductions," Brunello said. "It would help us, as state workers, to have some clear direction on what you do and you don't offset."

His quandary hit home after a recent trip to Brazil for which no offsets were purchased. When The Bee asked about that, Brunello decided to buy them himself.

"Do we need a policy for how this stuff works?" asked Sandy Cooney, a spokesman for the resources agency. "Absolutely, yes – because one does not exist."

To buy or not to buy

In all, more than two dozen top state officials and 19 legislators have logged more than a million air miles flying around the world on climate-related business since 2006, a recent Sacramento Bee investigation found. In the process, they emitted roughly 400,000 pounds of heat-trapping carbon dioxide into the atmosphere.

The Bee, which last month reported many state trips were funded by corporate donations routed through non-profit organizations, also found no shortage of surprises in the policy vacuum around carbon offsets.

While Gov. Arnold Schwarzenegger touts the value of offsetting travel and pays for it with his own money, some state employees will not say what choice they make.

"Offsets are a personal decision," said BreAnda Northcutt, deputy secretary of communications at the California Environmental Protection Agency who has traveled to Belgium, Poland, Germany, Britain and China on climate-related business. "I'd rather not discuss it."

Two of the governor's most trusted global warming gladiators hold divergent views.

Linda Adams, secretary of Cal-EPA and the state's lead climate negotiator, who has flown on official business to at least eight nations since 2006, said offsets help shrink her large carbon footprint. Like her boss, she pays for them herself.

"It's an individual choice," Adams said. "I think it's very important, and I'm very supportive of offsets in general."

Mary Nichols, chairwoman of the California Air Resources Board, which enforces the state's pioneering Global Warming Solutions Act of 2006, said the credits do not yet yield proven climate benefits.

"When I travel by airplane, I do not buy offsets," Nichols said in an e-mail. "I do not think offsets are particularly credible."

One type of offset popular with Adams and other state officials – the sale of credits representing carbon stored naturally in California forests – also is one that some specialists say falls short.

"Forestry offsets have a lot of superficial appeal," said Michael Wara, assistant professor at Stanford Law School and an expert on carbon trading. "But my view is that preserving forests as an offset is tough to do well – and the current state of the art in California is not good enough."

'Anyway' offsets

In the United States, where offset purchases are voluntary, they are traded in a regulatory netherworld with limited government oversight.

Across Europe, where emission reductions are mandatory, and where carbon offset trading is more widespread under the Kyoto protocol, Wara has uncovered flaws.

Call The Bee's Tom Knudson, (530) 582-5336.