More fucked up than previously reckoned:
THE world is on the cusp of a “tipping point” into dangerous climate change, according to new data gathered by scientists measuring methane leaking from the Arctic permafrost and a report presented to the United Nations on Tuesday.
“The permafrost carbon feedback is irreversible on human time scales,” says the report, Policy Implications of Warming Permafrost. “Overall, these observations indicate that large-scale thawing of permafrost may already have started.”
While countries the size of Australia tally up their greenhouse emissions in hundreds of millions of tonnes, the Arctic’s stores are measured in tens of billions.
Human-induced emissions now appear to have warmed the Arctic enough to unlock this vast carbon bank, with stark implications for international efforts to hold global warming to a safe level. Ancient forests locked under ice tens of thousands of years ago are beginning to melt and rot, releasing vast amounts of greenhouse gases into the air.
The rate of melt was “deeply concerning”, said Andy Pitman, the director of Australia’s Centre of Excellence for Climate System Science, an adviser to the Climate Commission, and a lead author of the Intergovernmental Panel on Climate Change’s reports.
“It had been assumed that on the timescale of the 21st century, that the effects of methane release would be relatively small compared to other effects – that’s why it has been largely left out of the climate models,” Professor Pitman said.
“I think it’s fair to say that until recently climate scientists underrated the rate at which permafrost melt could release methane. I think we’ve been shown to be over-conservative. It’s happening faster than we had thought … This is not good news.”
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