Rapidly thawing permafrost could double carbon emissions
A new study has found that the abrupt thawing of permafrost in the Arctic will double the carbon emissions suggested by previous estimates.
Scientists at the University of Colorada at Boulder have analysed the permafrost regions towards the Earth’s polar north, which is already dramatically altered by climate change.
Dr Merritt Turetsky, director of the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder, said the “fast and dramatic” thawing in the Arctic was “affecting landscapes in unprecedented ways”.
In her research paper, published in the journal Nature Geoscience, Dr Turetsky wrote: “Forests can become lakes in the course of a month, landslides occur with no warning, and invisible methane seep holes can swallow snowmobiles whole.”
“Systems that you could walk on with regular hiking boots and that were dry enough to support tree growth when frozen can thaw, and now all of a sudden these ecosystems turn into a soupy mess,” Dr Turetsky added.
Permafrost – the permanently frozen layer of soil beneath the layers which thaw and freeze based on the season – is present in 25% of all exposed land in the northern hemisphere.
It contains rocks, soil and sometimes pockets of pure ice – and crucially it stores twice as much carbon as is in the atmosphere because it is where life that once flourished in the Arctic is buried – from dead plants and animals through to microbes.
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This carbon-based matter has never fully decomposed but instead been frozen and locked away beneath the reach of the rest of the Earth for thousands of years.
According to current estimates, the permafrost contains an estimated 1,500 petagrams of carbon – basically equivalent to 1.5 trillion metric tons of carbon.
The change in emissions between previous estimates and those in the new study comes from the researchers’ distinguishing gradual permafrost thaw – which slowly releases the carbon stores – from abrupt thaws.
The issue is that 20% of the Arctic permafrost layer is rich in ice, meaning it is more susceptible to temperature changes and could thaw more rapidly.
Abrupt thaws are a large emitter of carbon, particularly carbon dioxide but also methane, which is an even more potent greenhouse gas.
According to the researchers, even though less than 5% of the Arctic permafrost is going to be rapidly thawing at any given time, emissions from that rapid thawing will equal the emissions from all of the other areas thawing more gradually.
Although there are a number of ways that abrupt permafrost thaw can happen, the results are always a dramatic change to the ecology.
The new study’s findings suggest it is an urgent matter to include permafrost-stored carbon in climate models, along with implementing strong climate policy and mitigation, Dr Turetsky added.
But the news isn’t all bad.
“We can definitely stave off the worst consequences of climate change if we act in the next decade,” she said.
“We have clear evidence that policy is going to help the north and thus it’s going to help dictate our future climate.”