Thawing permafrost and collapsing methane hydrates in the Siberian-Arctic Ocean could trigger increasing emissions of climate warming gases. The Russian-Swedish marine research expedition ISSS-2020 has been at sea in the Arctic on board the ship Akademik Keldysh since 26 September to address these major challenges in climate research. The expedition is first to document extensive gas leakage and elevated methane levels along a 150-kilometer-long stretch of the upper continental slope, six hundred kilometers offshore north of the Laptev Sea. Models have previously pointed this area out as being potentially sensitive to collapsing methane hydrates (frozen methane).
Thowing permafrost enhances global warming
There are enormous amounts of organic material, including the strong greenhouse gas methane, in permafrost on land and in the shallow seabed north of eastern Siberia, which is the world's largest coastal sea. It is also believed that there are large amounts of methane hydrates (frozen methane) along the continental slope north of these coastal seas.
“Greenhouse gas emissions from thawing permafrost and collapsing methane hydrates in the Arctic seabed are considered to be two mechanisms that, through positive feedback, can further increase global warming. Better understanding of these are two of the biggest challenges in climate research. The Eastern Siberian Arctic Ocean is "ground zero" for both thawing permafrost and collapsing methane hydrates in the seabed. There is a wide knowledge gap about these large but difficult-to-access systems at the other end of the Russian Arctic,” says Örjan Gustafsson, Swedish research leader for ISSS-2020 and Professor at the Department of Environmental Science and the Bolin Center for Climate Research.
Gas bubbles from the seabed
The researchers have observed gas bubbles being released from the seabed at a depth of around 300 meters. These observations were made by applying sonar technology along a 150-kilometer stretch of the continental slope in the Laptev Sea. This is an area that modeling studies have singled out as being sensitive to the collapse of methane hydrates (frozen methane), partly as a consequence of warmer Atlantic waters reaching this area. Chemical analyses of seawater samples on board the research vessel confirmed that the levels of methane in seawater in the area are elevated by about 10-100 times when compared to normal levels. This may be the first comprehensive observation of collapsing methane hydrates along the Siberian Arctic coast with subsequent methane release.
Methane bubbles from craters
The expedition team also found methane bubbles coming from round craters (pockmarks), which are depressions in the seabed, in other areas along the shallower coastal seas of the Laptev Sea and the East Siberian Sea. Several scientific publications from the ISSS programme and others have previously reported elevated methane levels in these coastal seas that formed at the end of the last ice age when glaciers melted and seawater levels rose and flooded the tundra's permafrost that consequently became seabed. The novelty in the discovery of these active craters lies in that they seem to be strong sources for the leaking methane that spreads over large areas both via ocean currents and via the air.
“Overall, we believe that these emissions currently do not yet have a major impact on climate. However, the new discoveries in combination with previous reports reinforce the idea that these systems of permafrost and methane hydrates in the Arctic seabed have now been triggered to release methane. Our main goal is to better understand the structure of these systems and how they work so that we can estimate the rate at which these emissions will increase in the future,”says Örjan Gustafsson.
Increasing emissions of greenhouse gases from natural systems add to the emissions already caused by human activities to contribute to global warming, Örjan Gustafsson continues. Thus, increasing greenhouse gas emissions due to thawing permafrost reduce the amount of greenhouse gases that can be tolerated for society to emit before thresholds set to avoid large-scale climate consequences are surpassed. We need to speed up the process of reversing society's greenhouse gas emission curve, a key global challenge for the coming decade. The observations made along with the samples taken during the cruise will be further analysed when the team returns and their final conclusions will be reported later in peer-reviewed scientific publications.
More about the ISSS 2020 expedition
Within the framework of the International Siberian Shelf Study (ISSS), Russian and Swedish researchers have collaborated for almost 20 years to underpin the link between the carbon cycle, greenhouse gases and climate change in the Arctic. Over the years, several expeditions took place in the Arctic on board both Russian and Swedish research vessels.This year’s expedition, the ISSS-2020, on board the Russian Academy of Sciences’ largest research vessel Akademik Keldysh, left the port of Archangelsk on 26 September to conduct a 6-week research cruise mainly in the eastern Siberian Arctic Ocean. There are twelve researchers from Stockholm University onboard under the leadership of Örjan Gustafsson, Professor at the Department of Environmental Science and the Bolin Center for Climate Research.
One of the biggest uncertainties in global warming is how thawing permafrost and collapsing methane hydrates in the seabed north of Siberia create “natural” emissions of greenhouse gases such as methane, carbon dioxide, and nitrous oxide (N2O). The ISSS-2020 expedition is made up of about ten research programs, each studying different parts of this complex system. The overall purpose of the expedition is to gain new knowledge about how these large and difficult-to-access systems are structured and function so that evidence-based predictions can be made on how greenhouse gas emissions from natural sources will evolve in the coming decades.
Additional reading
Article in The Guardian:
‘Sleeping giant’ Arctic methane deposits starting to release, scientists find
Follow the expedition on social media
Twitter: @ISSSarctic2020
Instagram: @arcticexpedition.isss2020
Facebook: https://www.facebook.com/ISSSarctic2020
Read about a recently published study on thawing permafrost from the same research group:
“Arctic Ocean sediments reveal permafrost thawing during past climate warming”
