[ad_1]
Millions of tonnes of organic carbon and methane under the Arctic Ocean melt and seep to the surface every year. And climate change could accelerate this publication of greenhouse gas, new research suggests.
the carbon attached in organic matter and methane (one carbon atom bonded to four hydrogen atoms) is currently trapped in underwater permafrost, which is frozen sediment that has been covered by 390 feet (120 meters) of water of sea towards the end of the Paleolithic Ice Age around 1800 1400 years ago, according to the US Geological Survey (USGS). Most of the submarine permafrost is found on the continental shelf under the Arctic Ocean, said study author Sayedeh Sara Sayedi, a doctoral student in the Department of Plant and Wildlife Science at Brigham University Young from Salt Lake City.
Because this sediment is in such an inaccessible place, there is only a few fragmentary data on how much carbon and methane is buried there and the rate at which these gases escape into the ocean and the atmosphere above it, Sayedi added.
Related: 6 unexpected effects of climate change
Some scientists Think of this reservoir of greenhouse gases as a time bomb, which could suddenly burst into the atmosphere and trigger a climate catastrophe. But Sayedi and his colleagues offer a different scenario: Instead of a sudden release, these gases have slowly and steadily seeped out of the permafrost for centuries. Of human origin climate change could make matters worse by accelerating the rate of release, but this acceleration would occur over several centuries, not decades or years.
“Still, the decisions we make today will make a difference in how it is affected,” Sayedi told Live Science.
In their new study, published on December 22 in the journal Environmental research letters, the team attempted to build a comprehensive picture of submarine permafrost using all the fragmentary data currently available; they also asked 25 permafrost scientists to use their expertise to estimate the amount of organic carbon 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 they estimated that permafrost currently contains around 60 billion tonnes (544 metric tonnes) of methane and 560 billion tonnes (508 metric tons) of organic carbon. .
Each year, about 140 million tonnes (128 metric tonnes) of carbon dioxide and 5.3 million tonnes (4.8 metric tonnes) of methane are released from permafrost into the atmosphere, they estimated. This is roughly equivalent to Spain’s carbon footprint, according to a statement. That said, due to the lack of data, these emission estimates remain highly uncertain, the authors noted.
The authors also concluded that, rather than being primarily due to recent human activity, much of these greenhouse gas emissions began after the last ice maximum, when the ice caps were at their greatest. extent. However, human-induced changes can further increase these emissions “in several hundred or thousands of years,” they wrote.
In fact, over the next 300 years, experts expect the rate of greenhouse gas emissions from underwater permafrost to increase dramatically if carbon emissions from human activity continue as usually. If emissions increase throughout the 21st century, permafrost would emit four times more greenhouse gases than if emissions started to decline by the end of this year and reach net zero by 2100.
Under the status quo scenario, the increase in emissions would accelerate over the next several centuries, but not yet enough to create a so-called “methane bomb”.
By neglecting underwater permafrost in climate change models, scientists run the risk of miscalculating how much greenhouse gases are emitted into the atmosphere, which could skew our emission reduction target, Sayedi said. . Over the next five to ten years, Sayedi said she hopes that further research on underwater permafrost could help fill our knowledge gaps and provide more certainty about how much carbon is actually there. -low – and on the quantity that comes out. Other factors, such as the extent of sea ice cover, can also affect the amount of gas leaking into the atmosphere, as the ice can act as a cap trapping the gas below, he said. she declared.
Originally posted on Live Science.
[ad_2]
Source link