AGU Conference: hitting climate target unlikey, insufficient
December 19th, 2008 by Jim JustThis week the American Geophysical Union has been holding its fall conference in San Francisco. Here are some highlights.
While many of the scientists presenting work dithered with whether stabilizing at 450ppm – or even higher – is economically and technologically feasible, James Hansen called for atmospheric greenhouse gas concentrations to be restricted to 350ppm. Hansen has said that we lower our target from 2°C to a 1°C increase above pre-industrial levels.
Olive Heffernon reports at Climate Feedback:
What is striking about the discussions on climate stabilization here this week is the overwhelming acceptance that we’ll overshoot even the 2°C target.
Dr. Eric Rignot, one of the world’s top ice sheet and sea-level rise experts, told attendees that one meter sea level rise by 2100 is “very likely” if the rate of ice melt just stays the same. What he didn’t address is what will happen if the rate of melt increases – as is expected.
Prof. David Rutledge of Caltech told the press that the fate of Earth’s climate hinges on the size of the world’s coal reserves – but how much coal remains is highly uncertain. Rutledge has estimated that coal reserves are much less than assumed in the IPCC scenarios and combustion of all remaining conventional oil, gas, and coal reserves would produce an atmospheric concentration of carbon dioxide of approximately 470 ppm in 2100, not too much above the 450 ppm that many climatologists argue we must achieve to avoid the worst impacts of climate change.
Of course that doesn’t consider feedback effects or other carbon sources such as methane. University of Alaska, Fairbanks scientists reported alarming news:
A team led by International Arctic Research Center scientist Igor Semiletov has found data to suggest that the carbon pool beneath the Arctic Ocean is leaking. . .
The new data indicates the underwater permafrost is thawing and therefore releasing methane. Permafrost can affect methane release in two ways. Both underwater and on land, it contains frozen organic material such as dead plants and animals. When permafrost thaws, that organic material decomposes, releasing gases like methane and carbon dioxide. In addition, methane, either in gas form or in ice-like methane hydrates, is trapped underneath the permafrost. When the permafrost thaws, the trapped methane can seep out through the thawed soil. Methane, a greenhouse gas 20 times more powerful than carbon dioxide, is thought to be an important factor in global climate change.
Incredibly, scientists, industry leaders and governments throughout the world are looking to methane to replace depleting oil and natural gas (Japan has a methane hydrate program and a state-backed drilling company has managed to extract industrial quantities of the gas). The amount of methane trapped as hydrates globally exceeds by many times the total combined oil, coal and natural gas reserves that have ever existed on earth. Release of methane correlates with previous rapid global warming events in Earth’s history.
Tar sands, oil shale development, deepwater oil extraction, the ongoing proliferation of coal-fired power plants, now methane hydrates. Methane hydrates – what are they thinking? Are humans as a species truly suicidal?