Even as the Trump Administration weighs withdrawing the United States
from the Paris climate agreement, a new scientific paper has documented
growing fluxes of greenhouse gases streaming into the air from the
Alaskan tundra, a long-feared occurrence that could worsen climate
change.
The new study, published in the Proceedings of the National Academy of Sciences, suggests that frozen northern soils - often called permafrost - are unleashing an increasing amount of carbon dioxide into the air as they thaw in summer or subsequently fail to refreeze as they once did, particularly in late fall and early winter.
"Over a large area, we're seeing a substantial increase in the amount of CO2 that's coming out in the [autumn]," said Roisin Commane, a Harvard atmospheric scientist who is the lead author of the study. The research was published by 19 authors from a variety of institutions, including Nasa's Jet Propulsion Laboratory and the National Oceanic and Atmospheric Administration.
The
study, based on aircraft measurements of carbon dioxide and methane and
tower measurements from Barrow, Alaska, found that from 2012 to the end
of 2014, the state emitted the equivalent of 220 million tonnes of
carbon dioxide gas into the atmosphere from biological sources (the
figure excludes fossil fuel burning and wildfires). That's an amount
comparable to all the emissions from the US commercial sector in a
single year.
The chief reason for the greater CO2 release was that as Alaska has warmed up, emissions from once frozen tundra in winter are increasing - presumably because the ground is not refreezing as quickly.
"The soils are warmer deeper, and as they freeze in the [autumn], the temperature of every soil depth has to come to zero before they hard freeze," Commane said. "The temperature has to come to zero and equilibrate, for the soils to freeze hard through. And through that whole period you have emissions because the microbe are active."
In particular, the research found that since 1975, there has been a 73.4 per cent increase in the amount of carbon lost from the Alaskan tundra in the months of October through December as the climate warmed steadily.
http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11852064
The new study, published in the Proceedings of the National Academy of Sciences, suggests that frozen northern soils - often called permafrost - are unleashing an increasing amount of carbon dioxide into the air as they thaw in summer or subsequently fail to refreeze as they once did, particularly in late fall and early winter.
"Over a large area, we're seeing a substantial increase in the amount of CO2 that's coming out in the [autumn]," said Roisin Commane, a Harvard atmospheric scientist who is the lead author of the study. The research was published by 19 authors from a variety of institutions, including Nasa's Jet Propulsion Laboratory and the National Oceanic and Atmospheric Administration.
The chief reason for the greater CO2 release was that as Alaska has warmed up, emissions from once frozen tundra in winter are increasing - presumably because the ground is not refreezing as quickly.
"The soils are warmer deeper, and as they freeze in the [autumn], the temperature of every soil depth has to come to zero before they hard freeze," Commane said. "The temperature has to come to zero and equilibrate, for the soils to freeze hard through. And through that whole period you have emissions because the microbe are active."
In particular, the research found that since 1975, there has been a 73.4 per cent increase in the amount of carbon lost from the Alaskan tundra in the months of October through December as the climate warmed steadily.
http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11852064
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