Millions of tons of organic carbon and methane under the Arctic Ocean thaw and spill to the surface every year. And climate change could accelerate this launch of greenhouse gases, suggests new research.
carbon organically bound and methane (a carbon atom bonded to four hydrogen atoms) are currently trapped in submarine permafrost, which is a frozen sediment that was covered by 120 meters of seawater by the end of the Paleolithic ice age. 1,800 1,400 years ago, according to the US Geological Survey (USGS). Most of the underwater permafrost is on the continental shelf under the Arctic Ocean, said study author Sayedeh Sara Sayedi, a doctoral student in the Department of Plant and Wildlife Sciences at Brigham Young University in Salt Lake City.
Because that sediment is in such an inaccessible place, there is only a bit of uneven data about how much carbon and methane is buried there and how quickly these gases escape into the ocean and atmosphere above, Sayedi added.
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some scientists considers this greenhouse gas tank to be a time bomb, which could suddenly drop into the atmosphere and trigger a climate catastrophe. But Sayedi and his colleagues propose a different scenario: rather than a sudden release, these gases have slowly and steadily emerged from the permafrost of centuries. Because of the man climate change it could make the situation worse by accelerating the release rate, but this acceleration would take place over several centuries, not decades or years.
“However, the decisions we make today will make a difference in how it will be affected,” Sayedi told Live Science.
In their new study, published in the journal on December 22 Environmental research letters, the team attempted to assemble a comprehensive picture of the underwater permafrost using all currently available fragmentary data; they also asked 25 permafrost scientists to use their expertise to estimate how much organic carbon is hidden in each specific layer of underwater permafrost. By compiling their perspectives, the team captured a more detailed picture of the ecosystem as a whole and estimated that permafrost currently holds approximately 60 billion tons (544 metric tons) of methane and 560 billion tons (508 metric tons) of organic carbon. .
Each year, about 140 million tons (128 metric tons) of carbon dioxide and 5.3 million tons (4.8 metric tons) of methane escape from the permafrost into the atmosphere, they estimated. This is roughly equivalent to Spain’s carbon footprint, according to a statement. That being said, due to the lack of data, these emissions estimates remain extremely uncertain, the authors noted.
The authors also concluded that, rather than being driven primarily by recent human activity, much of these greenhouse gas emissions began after the last glacial peak, when ice sheets were at their peak. to a greater extent. However, man-made changes can further increase these emissions “by hundreds or thousands of years from now,” they wrote.
In fact, over the next 300 years, experts expect the rate of greenhouse gas emissions from submarine permafrost to increase substantially if carbon emissions from human activity continue as usual. If emissions increased throughout the 21st century, permafrost would emit four times more greenhouse gases than if emissions began to decline by the end of this year and reach net zero by 2100.
Under the normal scenario, the increase in emissions would increase in the next few centuries, but it is still not enough to create the so-called “methane bomb”.
By overlooking underwater permafrost in climate change models, scientists risk miscalculating the amount of greenhouse gases that are emitted into the atmosphere, which could skew where we set our emission reduction targets, Sayedi said. Over the next five to 10 years, Sayedi said he hopes further research on underwater permafrost can help fill the gaps in our knowledge and provide more certainty about how much carbon is actually there – and how much is coming out. . Other factors, such as the extent of the sea ice cover, can also affect the amount of gas flowing into the atmosphere, because ice can act as a ceiling that traps gas from below, she said.
Originally published on Live Science.