Melting permafrost on the seafloor near the Arctic is creating skyscraper-sized ‘chasms’ and collapsing ground

Scientists from the Monterey Bay Aquarium Research Institute in the United States spent nine years studying an area of ​​about twenty-six square kilometers in the Beaufort Sea in Canada. During this period – very short – on the scale of geological time, researchers have seen more than half a million cubic meters of permafrost melt. Additionally, they found “sinkholes” the size of a few apartment blocks. Chasms are holes in the ground that are created by the collapse of the subsoil.

the painful consequences The disappearance of permafrost is already visible on the continent: houses in Yakutsk, Siberia, for example, regularly collapse as the subsoil thaws. Still at a depth of 120 to 150 meters below the sea, melting permafrost leads to ground collapse, this study shows for the first time.

On land, the human influence on the thaw is great. The bottom of the Arctic Ocean, on the other hand, is thawing mainly due to a much older process: the transition from the previous ice age to the current warm period. The melting of many ice caps has raised sea levels and flooded large coastal areas. This relatively warm water causes the permafrost to thaw slowly. The heat from the Earth’s core further accelerates this process. The permafrost thaws from the bottom up, creating “sinkholes”.

The researchers used sonar from their icebreakers: sound waves that travel through water and bounce off permafrost. The longer the sound waves take to return to the transmitter, the farther they travel from the seabed. With this technique, the researchers produced a 3D map of the seabed, with a measurement point every two meters. An underwater robot carried out additional measurements which showed deviations in the bottom of less than one meter.

In addition to the loss of permafrost and the creation of gigantic sinkholes, researchers have found so-called “pingos”. They are pimples in the permafrost that form when meltwater rises, hits colder water, and freezes again. These structures further prove that water flows upward from permafrost.

Although researchers do not directly associate the thawing of the northern seabed with human-induced climate change, the disappearance of the permafrost itself will lead to further global warming. Permafrost contains materials that, after thawing, can be broken down into methane, a powerful greenhouse gas, which will find its way into the atmosphere.

These new findings are valuable, according to Paul Overduin, a permafrost researcher at the Alfred Wegener Institute in Potsdam, not involved in the new study. “It’s surprising that such significant changes can take place in just nine years,” he says. Overduin is curious to what extent the seabed is also thawing in other parts of the Arctic. This will make it possible to understand the role that the thawing of the Arctic seabed plays in global warming.