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AGU Meeting: Jim Hansen on pacts with the devil

“We have a much sharper knowledge of global climate sensitivity than is usually stated and the Faustian bargain we have cut for ourselves is nastier than we have recognized,” said Jim Hansen of NASA to a packed lecture theatre on day three of the AGU Fall Meeting.

Hansen believes that governments don’t yet recognize the urgency of climate change. “There are a lot of governments who say they understand the problems, but a lot of it is greenwash,” he said. “The Venus Syndrome [in which Earth undergoes runaway warming and the oceans boil off] is the greatest threat to humanity’s existence. Earth is Goldilock’s choice of the planets - not too hot, not too cold, it’s just right.”

In the past there have been several periods where temperatures have dropped so low that the planet entered a “Snowball Earth” state, with ice covering the entire surface of the globe. But that slows the process of weathering by rocks and enables carbon dioxide levels to build up in the atmosphere, eventually leading to warming.

According to Hansen, there is no escape from the Venus Syndrome, which could occur for a forcing of 10-20 Watts per square metre. For comparison, the net forcing today is between 0 and 3 Watts per square metre. Although in the past carbon dioxide levels have reached 4000 parts per million (ppm) without a runaway warming effect, solar irradiance was lower. And today humans are increasing carbon dioxide levels at 2 ppm per year, 10,000 times faster than natural rates, which does not allow time for feedback effects to kick in.

“If we burn all the coal, we might kick in a runaway greenhouse effect, and if we burn all the tar shale and tar sands we definitely will,” said Hansen, who reckons we could decide to leave coal in the ground or use it only with carbon dioxide capture and storage. “We’re going to have to figure out how to power ourselves without it anyhow so why not do it sooner rather than later?”

Hansen is a strong advocate of a carbon tax, the profits of which go to the public to encourage them to buy into new technologies. “Caps aren’t going to work,” he said. “I think we will solve the problem but that does require a carbon price that is significant and rising.” He also believes that the US should have continued R&D on fourth-generation nuclear power, which enables the burning of nuclear waste to leave substances with a radioactive half-life of a few tens of years rather than tens of thousands of years.

Posted by Liz Kalaugher on December 19, 2008 12:58 AM | Permalink