3. SCIENCE: NASA's Hansen calls for severe CO2 cuts (ClimateWire, 06/24/2008)

Lauren Morello, ClimateWire reporter

Stabilizing the world's climate will require cutting the level of carbon dioxide in the atmosphere to just 350 parts per million, 30 percent lower than the 450 ppm target at the base of the Senate's recent climate bill, NASA climatologist James Hansen said yesterday.

Speaking in Washington to commemorate the 20th anniversary of his declaration, during a Senate hearing, that global warming was already happening, Hansen said he is just as certain of his latest prediction.

"I have greater than 99 percent confidence -- 99.9 percent confidence -- that the dangerous level [of CO2] is no higher than 350 ppm, and that means we've already passed it," Hansen said. "We're at 385."

James Hansen. Photo by Arnold Adle, courtesy of NASA.

Solving the climate problem will require swift action to limit emissions, he said, calling for a tax on carbon. "We have to go to a zero-carbon society," he said. "You can't talk about 20 percent reductions, 40 percent reductions, 60 percent reductions."

Under Hansen's plan, the tax would be applied to oil, gas, coal and other fossil fuels at the first point of sale. Proceeds from the tax would be distributed in dividend payments to individual citizens. Doing so would give Americans incentives to buy low-carbon cars and other products, and help ease tax-driven rises in consumer prices, Hansen said.

Once a tax is in place, "I think the marketplace should make most of the decisions," he said.

Hansen has been compared to Paul Revere, the Revolutionary War hero, by environmentalists for his courage in making early warnings about the effects of man-caused carbon dioxide emissions. He said his plan would also halt construction of coal plants without carbon capture and sequestration technology, with the eventual goal of ending emissions from coal plants worldwide by 2030.

That may be a tough sell at a time when gas prices are hovering at $4 per gallon -- or higher -- and the White House and Congress are again tussling over proposals to open the nation's outer continental shelf to oil drilling.

Expanding U.S. oil production: 'exactly the wrong thing to do'

But Hansen said he believed trying to expand American oil production would result in small, short-term gains -- at the expense of long-term climate health. "It's exactly the wrong thing to do," he said. "It just extends your addiction slightly and guarantees we'll go past the tipping point" of irreversible climate change.

Hansen said he is already concerned about the effect warming temperatures are having on wildlife populations, marine life and the world's glaciers, ice sheets and sea ice.

"We have already reached one tipping point," he said. "We are going to lose all sea ice in the Arctic in the summer season."

Last year, scientists recorded the lowest level of sea ice cover in the Arctic since satellite measurements began in 1979. The ice that reformed this winter is thin and vulnerable, leading many scientists -- including Hansen -- to conclude that this year could bring a record or near-record low ice level.

"If we have the same weather this year as we had last year, we'll get less ice," Hansen said. "Over the next five to 10 years, we are almost certainly going to lose all that sea ice."

Hansen is one of a group of 150 scientists, politicians, business executives and environmental advocates who took out full-page ads in yesterday's New York Times, Financial Times, International Herald Tribune and Swedish daily papers supporting the 350-ppm carbon dioxide target.

"350: Remember this number for the rest of your life," reads the ad's headline.

The group -- backed by the Stockholm Environment Institute and the Tällberg Foundation -- is asking governments to adopt the 350 ppm target during negotiations on a treaty to succeed the Kyoto Protocol, the United Nations pact for fighting global warming that is scheduled to end in 2012.

Along with Hansen, signers of the ad include Robert Corell, director of the Heinz Center's Global Change Program; the European Union Environment Agency, ex-Swedish Prime Minister Göran Persson; and José María Figueres, the former president of Costa Rica.

Reporter Katie Howell contributed.

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