In 10 seconds? Researchers have recently discovered what impact the thawing permafrost submerged at the edge of the Arctic ocean is having on the seafloor… and infrastructure. Their fascinating discovery helps explain the instability that people are observing on land.
Why is this study important? Permafrost is frozen ground that is found anywhere, both on land and underwater, where the mean annual temperature is 0 ºC or less. Numerous studies have looked at the effects that thawing underwaterpermafrost has on the land but this is the first study to demonstrate the significant impact that this thaw is having on the seafloor.
What’s happening? The researchers mapped an area of the seafloor at the shelf edge of the Canadian Beaufort Sea and discovered that the thawing permafrost is resulting in rapid changes. These include massive sinkholes that are as deep as a 6-story building is high, as well as rising ice-filled hills called pingos. This discovery helps explain why the thawing permafrost leads to unstable land, causing damage to infrastructures such as roads, airports, train lines, and buildings.
6-story deep sinkholes? What’s behind this? There isn't a lot of long-term data for the temperature of the seafloor in this area but the available data suggests that the thawing of permafrost in the ocean is not only due to climate change but is also driven by older and slower changes in the climate that have been occurring since the end of the last ice age. The researchers suggest that the changes to the permafrost that are occurring at the edge of the Arctic ocean are the result of warmer groundwater ascending to the surface, thawing the permafrost, and accelerating permafrost degradation.
How did they figure this out? MBARI, in collaboration with the Canadian Coastguard and the Korean Polar Research Institute, carried out repeated high-resolution underwater surveys of the shelf edge of the Canadian Beaufort Sea. These surveys occurred at 2- to 9-year intervals and enabled the researchers to observe changes in the seafloor morphology. In 2010 and 2019, these surveys were completed using ship-mounted multibeam sonar and the largest repeat mapping area was 25.9 km2. The data identified 41 sites where significant changes in the map of the seafloor had occurred. In 2013 and 2017, researchers used autonomous underwater vehicles (AUVs) to map the ocean floor. These surveys had a higher resolution and allowed to make comparisons across three time-frames (2010 – 2013, 2013 – 2017, and 2017 – 2019). While they did note some positive changes to the seafloor, this wasn't enough to match the considerable loss in the volume of the permafrost observed.
What does this mean for Canada's Arctic regions? Canada's Arctic regions are observing drastic changes as a result of rapidly rising temperatures leading to reduced summer sea ice, thawing permafrost, and an increase in the frequency and intensity of extreme weather. Already, changes in the Canadian Arctic are harming food security and limiting transportation, damaging the infrastructure, and blocking travel routes to traditional hunting grounds. This research provides valuable information on what is happening with the underwater permafrost and is useful for both the Government of Canada and the Inuvialuit people who live on the coast of the Beaufort sea. Monitoring these changes enables researchers to identify geohazards that are capable of causing widespread damage and enable governments to identify vulnerable areas and introduce adaptation policies.
So, what can we expect in the future? More information is needed to understand the reasons behind the thawing of submarine permafrost and what this means for the future of these areas. The team will return to the Arctic in the summer of 2022 to carry out a more comprehensive mapping of the seafloor. In addition, MBARI will launch a portable remotely operated vehicle (MiniROV) to help researchers obtain seafloor samples. It is hoped that this research will further advance our knowledge of what is happening below the surface, providing important information that can be used to identify potential hazards, inform environmental policies and create adaptation strategies for the people that live there.
About a quarter of the entire Northern Hemisphere is permafrost...
It is found throughout the Arctic and subarctic regions as well as at high elevations and on the seafloor.
In some regions, such as northern Siberia and Canada, the permafrost can reach depths of more than 700 meters.
Permafrost contains 1700 billion tons of organic material! To put this into perspective, this is nearly half of all the organic material contained in all the soil on Earth.
It also is a good carbon store, containing nearly four times the amount of carbon that has been released into the atmosphere as a result of human activities.
Dr. Lindy Whitehouse has distilled 8 research papers, saving you 28 hours of reading time.
The Science Integrity Check of this 3-min Science Digest was performed by Dr. ASM Mainul Hasan.