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Thawing Arctic Permafrost Could Cause 30,000 Active Landslides on One Small Canadian Island Every Year in the Future

Landslides on an island in the Canadian Arctic have risen sixtyfold since the mid-1980s due to the thawing permafrost, according to scientists studying the effects of climate change. 

The landslides have choked bodies of water with silt on the 70,000 square kilometers Banks Island in the Canadian Arctic; have made fishing harder for the island’s Inuvialuit community; and released greenhouse gases by thawing and exposing organic materials which then rot. 

The study, published in the journal Nature Communications explored a phenomenon called retrogressive thaw slumps, which happen when ground ice in the permafrost melts. Permafrost is the term used to describe ground which stays frozen for at least two years. The scientists conducted their study by analyzing images from the free-to-use Google Earth Engine Timelapse sheet.

Between 1984 and 2015, the number of retrogressive thaw slumps spiked 60 times, from 63 in 1984 to 4,077 in 2013. 

By 2015, an area the size of the island of Manhattan, or 60 square kilometers, had been disturbed, Antoni G. Lewkowicz, a professor in the Department of Geography, Environment and Geomatics at the University of Ottawa, told Newsweek.

Of the total retrogressive thaw slumps that happened since 1984, 85 percent took place after unusually hot summers of 1998, 2010, 2011 and 2012, the study revealed. 

Lewkowicz said: "Other studies from smaller areas of Banks Island had shown that retrogressive thaw numbers were increasing and Inuvialuit had reported seeing more slumps and exposed ground ice. We looked at the entire island and were truly staggered by the scale of the change.

"We could also see that the northern part of the island was not affected much in 1998 when it was not particularly warm there, but was affected more in the later years when it was much warmer probably because there was less sea ice in the Northwest Passage by then. This implies that other permafrost areas with lots of ground ice may be affected in the future as they warm up."

And as global warming continues and warm summers become more commonplace, the team predicts there could be 10,000 retrogressive thaw slumps initiated every decade on Banks Island over the rest of the 21st century.

"That would mean about 30,000 active in any year, compared to 4,000 at present," Lewkowicz said. If the global warming progresses more quickly than current estimates forecast, there could be even more landslides, he warned.

Retrogressive thaw slumps have dumped sediment into streams, lakes and the ocean: The team found more than 250 lakes on the island that were “choked with sediment,” Lewkowicz said.

“The Inuvialuit who live in Sachs Harbour on Banks Island have reported that it is harder to get around the island now for hunting and fishing because of the number of thaw slumps. And thaw slumps export organic material which was previously frozen in the permafrost. The subsequent breakdown of this organic material by bacteria to form carbon dioxide or methane will contribute additional greenhouse gases to the atmosphere, causing further global warming. Finally, we’ve learned that even areas of cold permafrost are vulnerable to climate warming.”

And while there will always be warmed and cooler summers, Lewkowicz explained that as the global climate heats up, the warmest summers will become even hotter over time. 

"This study shows how important that can be. Just two hot summers resulted in more than 3,000 landslides being initiated, half of which will remain active for more than 30 years," he said. 

"We can’t stop thaw slumps from starting or stabilize the thousands of active thaw slumps. We can only make changes in our own lives to reduce our carbon footprint, and we can encourage our politicians to take the necessary measures to help reduce our greenhouse gas emissions so that future warming is as limited as possible," said Lewkowicz.

Martin Siegert, a professor and co-director of the Grantham Institute at Imperial College London who was not involved in the research, told Newsweek: "This looks like a consistent story alongside Arctic warming, which is two times the global average, heating up the land that is normally permanently frozen."

Julian Murton, a professor of permafrost science at the University of Sussex, in the U.K., who was not involved in the research, told Newsweek: "The key significance of the study is the revelation that parts of the colder northern regions of the Arctic, that I think have experienced limited geomorphic activity for at least several thousand years, are now starting to undergo a major pulse of landscape change.”

“The ecological consequences of widespread slumping on terrestrial and aquatic ecosystems and nutrient budgets is of major concern," he warned. "Slumping represents a big disturbance to these systems, and their resilience and adaptation need to be investigated to see how the Banks Island ecosystem copes with such landscape change."

However, he pointed out that the study was limited because of the spatial resolution of the satellite images. “Big slumps are easy to spot, whereas little slumps or incipient slumps may be easy to miss,” he said.

Dr. Antonio Abellán​, a lecturer in engineering geology at the University of Leeds who did not work on the research told Newsweek the 60-fold increase researchers noted could have been a reflection of a combination of key factors in the reactivation of landslides in the permafrost, "such as the progressive strength reduction of the slope due to a loss of ice as a combination of heat waves and warm precipitation, yielding a more efficient ice melting effect than simple heat conduction." 

"Nevertheless, heat convection was not considered in this research due to a series of parametric uncertainties in the precipitation record derived from an insufficient historical record, reduced number of weather stations and lack of spatial representativeness."

He continued: "Understanding and modeling the physical mechanisms behind the quick slope response to heat transfer is where our scientific efforts should be focused in order to forecast slope reactivation in Arctic environment under future climate scenarios."

The study comes as scientists attempt to understand the gravity of problems posed by climate change and global warming, and find solutions to the problems posed by them.

One team at Harvard University is taking the imaginative approach of trying to create a genetically engineered elephant-mammoth hybrid. The hardy animals could one day be released in the vast tundra and boreal stretches of North America and Eurasia, where they would press down on the ground and scrape back thick layers of winter snow so the cold can penetrate the soil. This, they believe, would prevent frozen soil, packed with leaves and other organic materials, from being exposed and releasing greenhouse gases.

This article has been updated with comment from Dr. Antonio Abellán​.

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