According to the National Snow and Ice Data Center (NSIDC), over the past 30 years, the Arctic region has warmed more than any other region on earth due to human-caused climate change. The NASA figure below–an averaged temperature profile from the South Pole to the North Pole–shows that the largest warming is in the northern latitudes and the Arctic.
Public attention on Arctic warming has focused mostly on the melting of the Greenland ice sheet and the disappearance of Arctic sea ice. But just centimeters below the Arctic’s land surface is a ticking time bomb that could detonate as global temperatures rise. It’s called permafrost.
Permafrost is found at high altitude mountains, in Antarctica and, especially, in the Arctic. In permafrost, ice binds together soil, rocks, sand, and organic matter. Some of that organic matter includes the remains of plants and animals that have been frozen since the last Ice Age, more than 11,000 years ago.
Permafrost thaw is one of the gravest, yet lesser discussed, impacts of climate change. There are an estimated 1,400 gigatons of carbon frozen in Arctic permafrost. That’s about four times more than the carbon humans have emitted since the Industrial Revolution. As global temperatures rise, the permafrost may thaw, exposing the organic matter below the surface.
Even though the thawing rate may be uncertain, the thawing of permafrost has enormous implications for climate change. According to a recent report, a 3.6-degrees Fahrenheit ( 2 degrees Celsius) increase in temperature—expected by the end of the century—may result in a loss of about 40% of the world’s permafrost by 2100. As permafrost thaws, the organic matter locked within will start to decompose, releasing even more climate-warming carbon dioxide and methane into the atmosphere. Thawing can also open pathways for methane to rise up from reservoirs deep in the earth. These additional sources of greenhouse gases will cause further warming. Thus the endless cycle–warming causes permafrost to thaw and the greenhouse gases emitted from thawing cause further warming–forms a positive feedback.
Scientists are also studying how thawing permafrost may lead to the reemergence of harmful bacteria and diseases that have been frozen in the earth for hundreds of years. In 2016, an anthrax outbreak from a rotting reindeer carcass found in the permafrost caused over 70 people to be hospitalized in northern Russia, and killed a child and more than 2,300 reindeer. Officials did not know exactly how the outbreak started, but the hypothesis was a heat wave had thawed the frozen soil there exposing a reindeer carcass infected with anthrax decades ago. Some scientists think this incident could be an example of what permafrost thawing may bring.