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Arctic permafrost has been waning slowly over the centuries releasing methane gas into the atmosphere. However, a sudden thawing of frozen soil and rock has scientists concerned this will lead to alarming climate feedback loops.
According to a new collaborative study conducted by researchers at the University of Colorado Boulder and University of Guelph, the melting of the permafrost could throw more CO2 and methane into the atmosphere.
The study published in Nature Geoscience warns that current evaluations where carbon emissions are concerned could be grossly underestimated. Findings argue that the impact of melting permafrost could double previous projections and there are some immediate effects already evident.
The amount of carbon coming off that very narrow amount of abrupt thaw in the landscape, that small area, is still large enough to double the climate consequences and the permafrost carbon feedback.
Merritt Turetsky, Associate Professor and Lead-author of the study, The University of Guelph
Thermokarst: Terra Soupy
As well as the potential for a dramatic increase in CO2 and methane scientists are now witnessing a phenomenon known as thermokarst, which results in a violent upheaval of the land surface as the permafrost melts. A process that would otherwise occur over the course of a few centuries or decades can accelerate with the rapid melts, suddenly thermokarst depression can develop over just a few months.
The dramatic effect on the landscape such as the disappearance of hillsides and collapsing of the ground soil can lead to the formation of sinkholes and small lakes. This is due to the fact that when the supporting ice melts, water begins to surface as the land sinks. “You get these pits on the land, sometimes meters deep. They're like sinkholes developing in the land… Essentially, we're taking terra firma and making it terra soupy,” Turetsky adds.
As the land suddenly shifts and changes leaving what is known as a karst landscape in its wake, the surrounding earth may eject increased amounts of carbon into the atmosphere. Furthermore, the researchers also deal with the consequences directly often losing equipment in areas under observation.
When you come back in, it's a lake and there's three meters of water at the surface. You have to probably say goodbye to your equipment.
Merritt Turetsky, Associate Professor and Lead-author of the study, The University of Guelph
Known Unknown
Turetsky and her team have gathered vast amounts of data and information that takes into consideration current as well as previous rapid permafrost thaws across a range of diverse terrains. This enabled the researchers to make projections concerning increased carbon release and abrupt changes in the landscape. What they discovered is that thermokarst almost always leads to flooding, landslides, and the appearance of sinkholes.
The lakes and ponds that form are often low in oxygen and contain a lot of microbes that prosper in this kind of carbon-rich environment. These blossoming microbes can then lead to more methane being released into the atmosphere.
While gradual thawing still leads to the appearance of wetlands and thaw lakes, the resulting carbon release is offset by regrowing vegetation as these areas often become rich in fauna. However, sudden thawing of the soil means that the soil uptake of carbon cannot match the release, and this is why current estimates of carbon emissions via permafrost could be far from the reality – now the challenge is trying to quantify the “known unknown” according to the team.
Enhancing Climate Models
"The impacts from abrupt thaw are not represented in any existing global model and our findings indicate that this could amplify the permafrost climate-carbon feedback by up to a factor of two, thereby exacerbating the problem of permissible emissions to stay below specific climate change targets," said David Lawrence, co-author of the study.
While more research is needed on the circumstance of abrupt permafrost thaws, this latest study highlights how climate modeling is a complex and uncertain system. Therefore, this kind of research can advance the accuracy of future models but only if taken seriously. While it will still “take decades” for these regions to significantly influence the climate system, according to Turetsky.
Therefore, in order to stop the long-term suffering of both the landscape and living species on Earth enhancing climate models is key. "We can definitely stave off the worst consequences of climate change if we act in the next decade," declared Turetsky.
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