As Arctic temperatures rise at a rate faster than twice the global average, the layer of perpetually frozen soil that lies underneath the tundra surface is thawing. Public attention has been mainly focused on the disappearance of Arctic sea ice, but scientists believe that the thawing soil, also known as permafrost, will have much more serious implications on climate change.
Permafrost occurs in areas where the temperature of the ground remains below the freezing mark for two or more years. Most of the world’s permafrost is found in the Northern Hemisphere, in northern Russia, Canada, Alaska, Iceland, and Scandinavia. However, it can also be found in the Rocky Mountains of Canada and Alaska, the Himalayans, the Alps and the high-altitude region Patagonia and New Zealand.
Climatologists currently predict that 2.5 million square miles of permafrost in the Northern Hemisphere could be gone by the end of the century. This is expected to release huge stores of carbon dioxide, methane and nitrous oxide that have been locked in the permafrost for centuries. The National Oceanic and Atmospheric Administration’s (NOAA) Arctic Report Card estimates that the release of carbon dioxide from frozen soil is already beginning to affect global warming.
“New regional and winter season measurements of ecosystem carbon dioxide flux independently indicate that permafrost region ecosystems are releasing net carbon (potentially 0.3 to 0.6 Pg C per year) to the atmosphere,” the NOAA writes in the report. This means that thawing permafrost could be releasing 300 to 600 million tons of net carbon per year into the atmosphere, about the same as the UK’s annual emissions. This is only expected to increase. “We think that [number] should be two to three times bigger by the end of the century based on the kind of forecasting we’ve done,” said Ted Schuur, a professor of Ecosystem Ecology at Northern Arizona University.
Scientists are concerned that this could be a tipping point. As Arctic permafrost warms, it releases carbon. That fuels further warming, which melts more permafrost, creating a positive feedback loop with deadly consequences. A study published in Nature Climate Change in 2017 predicted that 1.5 million square miles of permafrost would disappear with every additional 1 degree Celsius of warming. However, melting permafrost fueling climate change isn’t the only concern.
The tundra of the Arctic is typically covered in berries, shrubs and lichen that provides abundant food for bears, caribou and other animals. As permafrost thaws, the landscape begins to ‘slump’ or form landslides. These slumps have increased around the Arctic, and destroy the natural landscape of the area. If these landslides happened in urban areas, they could swallow dozens of buildings.
Still, these slumps are dangerous. The landscape changes make it increasingly difficult for indigenous people, like the Inuit, and Arctic animals to find food. The melting of ice that normally holds together peat, clay, rocks, sand and other sediment leads to lakes suddenly draining, seashores collapsing, and stream flows changing. “It’s not surprising when you consider that as much as 80 percent of the ground here consists of frozen water. When that ice melts, the frozen ground literally falls apart,” said Philip Marsh, a Canadian scientist and professor of hydrology at Wilfrid Laurier University.
Marsh’s research in Canada has led his team to conclude that climate warming will result in hydrological changes that could dry up 15,000 of the 45,000 lakes in the Mackenzie River Delta. He also expects to see more slumping along lakes in the Arctic. “As a result,” said Marsh, “indigenous communities, the resource industry, and the government need to better understand how a warming climate is impacting water resources and permafrost ecosystems.”
Another danger that melting permafrost introduces are deadly toxins and diseases. A study in Geophysical Research Letters found that Arctic permafrost is the largest storehouse of mercury on Earth. Mercury is a heavy metal that is highly toxic to humans. Scientists believe there is about 15 million gallons of mercury frozen in Arctic permafrost, which could be released into the ocean as the permafrost thaws.
Scientists are also investigating the possibility of old and dangerous diseases being released from frozen soil. An outbreak of anthrax in western Siberia resulted in the killing of 100,000 reindeer in 2016 and 2017. One person died from anthrax and several other reindeer herders fell ill. A record heat wave across Siberia that summer is believed to have thawed out reindeer carcasses from thousands of years ago that were infected with anthrax spores.
The Intergovernmental Panel on Climate Change (IPCC) has released a report collecting all of the evidence how the frozen regions of the world and the oceans are threatened by climate change. The report shows that even if the world manages to hit the IPCC target of limiting global warming to 2 degrees Celsius by 2100, around 25 percent of the permafrost near the surface of the Arctic will still be lost. If the world continues to increase emissions and hits 5 degrees of warming by the end of the century, around 69 percent could be lost.
The Arctic is warming faster than anywhere else on Earth. The thawing of permafrost will have devastating effects on the planet. Now more than ever, it’s important to act quickly and ensure that these types of positive feedback loops don’t spiral out of control. “If we set off these cascades, these potential accelerations, we may not be able to rein them back in,” says Schuur.