Thawing permafrost: The speed of coastal erosion in Eastern Siberia has nearly doubled

Alfred Wegener Institute: The high cliffs of Eastern Siberia – which mainly consist of permafrost – continue to erode at an ever quickening pace. This is the conclusion which scientists of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research have reached after their evaluation of data and aerial photographs of the coastal regions for the last 40 years. According to the researchers, the reasons for this increasing erosion are rising summer temperatures in the Russian permafrost regions as well the retreat of the Arctic sea ice. This coastal protection recedes more and more on an annual basis. As a result, waves undermine the shores. At the same time, the land surface begins to sink. The small island of Muostakh east of the Lena Delta is especially affected by these changes. Experts fear that it might even disappear altogether should the loss of land continue.

The interconnectedness is clear and unambiguous: The warmer the east Siberian permafrost regions become, the quicker the coast erodes. “If the average temperature rises by 1 degree Celsius in the summer, erosion accelerates by 1.2 metres annually,“ says AWI geographer Frank Günther, who investigates the causes of the coastal breakdown in Eastern Siberia together with German and Russian colleagues, and who has published his findings in two scientific articles.

...This increase in temperature is not without consequences. Whereas a thick layer of sea ice used to protect the frozen soil almost all year round, it now recedes in this part of the Arctic for increasing periods of time during the summer months. The number of summer days on which the sea ice in the southern Laptew Sea vanishes completely grows steadily. “During the past two decades, there were, on average, fewer than 80 ice-free days in this region per year. During the past three years, however, we counted 96 ice-free days on average. Thus, the waves can nibble at the permafrost coasts for approximately two more weeks each year,“ explains AWI permafrost researcher Paul Overduin.

The waves dig deep recesses into the base of the high coasts. The result: The undermined slopes break off bit by bit. During the past 40 years, the coastal areas surveyed retreated on average 2.2 meters per year. “During the past four years, this value has increased at least 1.6 times, in certain instances up to 2.4 times to reach 5.3 meters per year,“ says Paul Overduin.

For the little island of Muostakh east of the harbour town of Tiksi, this may well mean extinction. “In fewer than one hundred years, the island will break up into several sections, and then it will disappear quickly,“ predicts Frank Günther....

Waiting for supplies in Eastern Siberia, shot by NASA ICE, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license