TechThawing permafrost's climate bomb. CO2 emissions soar, study warns

Thawing permafrost's climate bomb. CO2 emissions soar, study warns

Permafrost

Images source: © Wikimedia Commons | Boris Radosavljevic

6:25 AM EDT, May 6, 2024

Permafrost is thawing, a phenomenon scientists link to alarming increases in carbon dioxide emissions. This forms a peculiar loop: climate warming from CO2 emissions triggers changes that further augment CO2 emissions.

Recent findings published in "Nature Geoscience" reveal that carbon dioxide emissions are significantly higher in areas where permafrost has thawed compared to regions where it remains intact. This highlights one of the critical climate feedback mechanisms accelerating global warming.

A Chinese Academy of Sciences team conducted complex research, shedding light on how carbon stored in permafrost affects climate change, especially considering future warming scenarios.

With rising temperatures, permafrost in high latitudes and altitudes is thawing rapidly. This process, known as thermokarst, impacts about 20% of the Northern permafrost region, a major reservoir of underground organic carbon. The rapid thaw alters land morphology and soil properties, which, in turn, can greatly upset the carbon cycle in these ecosystems.

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Until now, studies analyzing the differential impact of climate change on soil CO2 emissions, with or without thermokarst influence, have been scarce. The team led by Professor Yang Yuanhe sought to bridge this knowledge gap. Their findings showed that warming-induced CO2 emission increases were about 5.5 times higher in thermokarst-affected areas compared to unaffected neighboring regions.

Examining over 30 variables to understand this discrepancy, they found the heightened response to warming was primarily due to poorer soil quality and a higher presence of microorganisms breaking down organic carbon in thermokarst soils.

Further, by incubating soils from thawed permafrost areas in the lab, the team proved that thermokarst markedly heightens the temperature sensitivity of CO2 release, offering additional proof of stronger warming responses in affected terrains.

The researchers estimate that global warming's effect on all Northern Hemisphere high-altitude thermokarst regions could increase carbon emission from the soil by roughly 0.4 petagrams (882 billion pounds) annually. This represents about a fourth of the projected carbon losses from permafrost by the century's end, indicating that thawing permafrost could lead to much higher atmospheric carbon emissions than previously thought.

Permafrost spans about a quarter of the Northern Hemisphere's land surface, covering half of Canada and 80% of Alaska, and represents one-sixth of Earth's terrestrial area. Frozen for millennia and in places reaching depths of a mile, these substrates hold carbon that, upon thawing, decomposes and releases methane and CO2.

In 2019, "Nature Communications" reported a decade-long study showing a 0.3 degrees Celsius (0.54 degrees Fahrenheit) increase at 33 feet depth across all regions, with the most significant rise in the Arctic. These permafrost areas contain twice the atmospheric carbon dioxide volume.

That same year, University of Leeds researchers warned of permafrost in peatlands across Europe and western Siberia nearing a thawing threshold, storing 39 billion tons of carbon—double that of all European forests. Despite efforts to curb carbon emissions, climate models predict that, by 2040, the climate in northern Europe could be too warm to sustain permafrost. However, timely climate action might preserve it in northwestern Siberia, home to 13.9 billion tons of carbon.

Permafrost thawing impacts infrastructure across the Arctic, with studies indicating significant risks to buildings, roads, pipelines, and airports essential to local communities. With climate warming, over 120,000 buildings, 25,000 miles of roads, and 5900 miles of pipelines and runways are increasingly threatened, necessitating greater maintenance efforts and financial investments to safeguard these structures. By 2050, up to 70% of Arctic buildings and 30-50% of critical infrastructure could face destruction.