Permafrost: what are the consequences for the climate?
In Umiujaq (pronounced “umiak”) in the Canadian Arctic, climate change is visible in the soil and even below. For the last five years, Florent Dominé and his teams have been working in the complete weather station they set up to take readings from the soil to check its thaw rate and CO2 emissions.
The CNRS research director, who is also one of the most prolific Arctic researchers, initiated the Acceleration of Permafrost Thaw (APT) programme with the support of the BNP Paribas Foundation and no less than eight French and Canadian laboratories. He spoke about his experience and research at the recent Climate Initiative conference held on 19 February at the BNP Paribas Foundation premises and hosted by future-explorers Usbek & Rica magazine.
No fewer than 15 million square meters of the Earth’s soil is permanently frozen. This phenomenon is known as permafrost and is concentrated in the Northern Hemisphere, from Alaska to the western edges of Siberia. “In the summer heat, there is surface layer thaw to a depth of 20 cm in the High Arctic and three metres in the subarctic”, Florent Dominé explains. “This sometimes results in what we call a polygonised landscape: due to the thermal retraction of ground in winter, cracks form and allow water to infiltrate and freeze, thus forming a network of polygons. During the summer thaw, the polygonised soil often seen in the Arctic is exposed.”
So why are these particularly beautiful landscapes of interest to scientists? Because permafrost thaw has the potential to become one of the major causes of global warming.
“The organic matter contained in the frozen soil does not decompose, which means that permafrost has been storing massive amounts of trapped carbon for millennia. The carbon released with the current thaw is being consumed by bacteria, producing CO2 and CH4 emissions - the most potent of greenhouse gases - which will accelerate warming”, the scientist explains.
Permafrost has been storing massive amounts of trapped carbon for millennia.
Climatologists call this accelerated thaw mechanism a “positive feedback loop”, i.e. a phenomenon which leads to the amplification of global warming. No one actually knows how organic matter trapped in ground as hard as cement will decompose. How long will it take for this matter to warm and what quantity of greenhouse gas will it release? Then there are the associated health risks: “microbes that have been frozen in the permafrost for millennia can come back to life after the thaw.” We have already seen the reemergence of ancient viruses like anthrax, as recently discovered by French and Russian researchers.
Ticking time bomb for the climate
History demonstrates that permafrost thaw can also be a natural phenomenon. “Past episodes show how this occurrent with sharp increases in temperature”, Dominé explains. Yet the IPCC, which publishes the benchmark summary report on the climate, does not factor in these processes in its climate forecasts. Compared to other causes of global warming, such as the burning of fossil fuels and deforestation, its impact seems marginal at this stage. But if the thaw continues at this rate it will be the third major cause of global warming. “We are looking at a climate bomb”, Dominé explains, “and the current forecasts of the IPCC models could turn out to be very optimistic”.
Much more still needs to be done to change mentalities and accelerate awareness, particularly since researching the phenomenon is more complex than it seems. “We regularly come across new processes, like the role of vegetation”, Dominé explains. Global warming has in fact favoured the development of shrubs which trap snow, which increases their insulation and prevents the soil from freezing in winter. Thus, soil can warm more quickly. This vegetation also constitutes a second positive feedback loop in favour of warming and is within the first positive feedback loop.
Researching permafrost is also an immense physical challenge. Every year, Dominé travels at least four or five times to these incredibly remote areas of abundant permafrost. “A lot of logistics goes into these trips, as the most isolated parts can only be reached by small plane and snowmobiles”. The camp on Ward Hunt Island is nothing more than a glorified tent with an oil stove. “[Research takes place] from the end of May to early June at temperatures between -5° and -20°… which is actually quite comfortable provided there’s no wind”, says the researcher with a touch of irony, while joking about the risks of living with particularly hungry bears nearby.
The scale of the work has also made it necessary to form alliances. “Permafrost thaw affects millions of km2 and we alone cannot monitor such vast expanses”, explains Dominé. The University of Sherbrooke recently joined the team to research permafrost thaw, which it detects by changes in microwave emissions as measured by the SMOS satellite. Doing so makes it possible to have more accurate readings of the extent of the damage. On a positive note, researchers are pinning their hopes on negative feedback loops which could keep global warming in check by trapping some of the carbon. “It can be sedimented and trapped on the ocean floor, although we don’t know how much such reservoirs can adsorb”, cautions Dominé.
However, the scientist does not believe that such natural processes will defuse the climate bomb. It is worth remembering that climate change is caused by human activity, and this is where there is scope for action through collective measures and by adapting individual behaviours.
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