Groggy climate giant: underwater permafrost still awakens after 12,000 years

In the north, the swollen Arctic Ocean yielded a large number of coastal tundra and steppe ecosystems. Although ocean water was only a few levels above freezing, it began to melt the permafrost beneath, exposing billions of tons of organic matter to microbial breakdown. The decaying organic matter began to produce CO2 and CH4, two of the most important greenhouse gases.

Although researchers have been studying submarine pollution for decades, the difficulty of collecting measurements and sharing data across international and control divisions has prevented an overall estimate of the is of carbon and the level of their release. A new study, led by a Ph.D. candidate Sara Sayedi and senior researcher Dr Ben Abbott at Brigham Young University (BYU) published in IOP Publishing journal Environmental Research Letters, shedding light on submarine climate feedback, generating initial estimates of cyclic carbon stocks, greenhouse gas emissions, and possible future response the underwater permafrost zone.

Sayedi and an international team of 25 permafrost researchers worked under the coordination of the Permafrost Carbon Network (PCN), which is supported by the U.S. National Science Foundation. The researchers combined results from published and unpublished studies to estimate the amount of submarine carbon stock in the past and the amount of greenhouse gas it could produce across the three. centuries to come.

Using an approach called expert assessment, which combines several plausible, independent values, the researchers estimated that the submarine area currently captures 60 billion tonnes of methane and 560 billion tonnes of organic carbon in sediment and soil. For information, humans have released about 500 billion tons of carbon into the atmosphere since the Industrial Revolution. This makes submarine carbon stocks a feedback from a major ecosystem in terms of climate change.

“Underwater permafrost is very special because it still responds to climate change more than ten thousand years ago,” Sayedi said. “In some ways, it can give us a glimpse of the possible response. to have a permafrost that is melting down today because of human activity. “

Estimates from the Sayedi team suggest that underwater permafrost already emits large amounts of greenhouse gas. However, this distribution is largely due to an ancient climate change rather than normal human activity. They estimate that underwater permafrost releases around 140 million tonnes of CO2 and 5.3 million tonnes of CH4 into the atmosphere each year. This is similar to the size of a greenhouse gas footprint in Spain.

The researchers found that if human-induced climate change persists, the release of CH4 and CO2 from submarine perennials could increase dramatically. However, this response is expected to occur over the next three centuries rather than abruptly. Researchers estimated that the rate of future greenhouse gas emissions from submarine basins is directly dependent on future human emissions. They found that, under normal industrial conditions, warming submarine warming emits four times more CO2 and CH4 than when human emissions are reduced to warming less than 2 Maintain ° C.

“These results are important because they show great but slow feedback in the weather,” Sayedi explained. “Some coverage in this area has suggested that human emissions may accidentally release methane hydrates, but our study suggests a gradual increase over many decades.”

Even if the climate feedback is relatively gradual, the researchers reveal that underwater permafrost is not included in conventional climate agreements or greenhouse gas targets. Sayedi confirmed that there is still a lot of uncertainty about submarine sustainability and that further research is needed.

“Compared to how important underwater permafrost could be for future climate, we don’t know much about this ecosystem,” Sayedi said. “We need more sediment and soil samples, as well as a better monitoring network to find out when greenhouse gas emissions respond to conventional warming and how quickly this large amount of carbon will rise from the ground. -His frozen pit. “

https: //iopscience.iop.org /article /10.1088 /1748-9326 /abcc29

This research was funded by the U.S. National Science Foundation and BYU Postgraduate Studies.

Summary of key scientific points:

• Underwater permafrost has been melting since the end of the last glaciation period (~ 14,000 years ago) when the ocean began to flood.
• An international team of 25 permafrost researchers estimates that the submarine area currently captures 60 billion tons of methane and 560 billion tons of organic carbon in sediment and soil . However, the exact extent of these carbon stocks remains highly uncertain.
• This carbon has already been released from a permanent underwater area, although it is unclear whether this is a natural response to deglaciation or whether anthropogenic warming accelerates greenhouse gas production and emissions. .
• The researchers estimate that, at present, the submarine area releases approximately 140 million tons of CO2 and 5.3 million tons of CH4 into the atmosphere each year. This represents a small fraction of anthropogenic greenhouse gas emissions – around the same rate as Spanish greenhouse gas emissions.
• Experts predict a gradual increase in emissions from submarine perennials over the next three hundred years rather than a sudden release.
• The amount of greenhouse gas emissions depends on the amount of human emissions that are reduced. Experts estimate that around ¾ of the additional underwater emissions can be avoided if people actively reduce their emissions compared to an unmitigated situation.
• This climate feedback is virtually absent from climate policy discussions, and more site observation is needed to better predict the future of this system.

Quotes from other co-authors:

“I think there are three important messages from this study. First, underwater permafrost may not be a climate time bomb on hair stimulation. Second, underwater permafrost is a climate feedback could be considered in climate compromise.Tirdly there is still a lot we don’t know about this system.We really need further research, including co -operation across northern countries and fields of research. ”

Dr. Ben Abbott, senior researcher on the project, Brigham Young University

“This work demonstrates the power of science synthesis and networking by bringing together experts across a range of disciplines to assess our state of knowledge based on currently available ideas and models. While scientific work What remains to be done to confirm these views, given that experience combined with this expert assessment provides an important basis for shaping future research into submarine greenhouse gas emissions. “

Dr. Ted Schuur, Principal Investigator of the Permafrost Carbon Network, University of Northern Arizona

“This expert assessment is a vital contribution to the scientific literature in advancing our knowledge of submarine climate and greenhouse gas emissions from this tank to date. datapoints or surveys provide a much more complete estimate of submarine permanence. “

Dr. Christina Schädel, Associate Researcher of the Permafrost Carbon Network, University of Northern Arizona

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High resolution versions of the pictures and photos can be found at this link.