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kassy

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Re: Permafrost general science thread
« Reply #50 on: November 11, 2019, 01:58:17 AM »
Arctic Shifts To a Carbon Source Due to Winter Soil Emissions
https://eurekalert.org/pub_releases/2019-11/nsfc-ast110819.php

A NASA-funded study suggests winter carbon emissions in the Arctic may be adding more carbon into the atmosphere each year than is taken up by Arctic vegetation, marking a stark reversal for a region that has captured and stored carbon for tens of thousands of years.

The study, published Oct. 21 in Nature Climate Change, warns that winter carbon dioxide loss from the world's permafrost regions could increase by 41% over the next century if human-caused greenhouse gas emissions continue at their current pace. Carbon emitted from thawing permafrost has not been included in the majority of models used to predict future climates.

"These findings indicate that winter carbon dioxide loss may already be offsetting growing season carbon uptake, and these losses will increase as the climate continues to warm," said Woods Hole Research Center Arctic Program Director Sue Natali, lead author of the study. "Studies focused on individual sites have seen this transition, but until now we haven't had a clear accounting of the winter carbon balance throughout the entire Arctic region."

Researchers estimate a yearly loss of 1.7 billion metric tons of carbon from the permafrost region during the winter season from 2003 to 2017 compared to the estimated average of 1 billion metric tons of carbon taken up during the growing season. ... "The warmer it gets, the more carbon will be released into the atmosphere from the permafrost region, which will add to further warming," ... . If fossil fuel use is modestly reduced over the next century, winter carbon dioxide emissions would increase 17% compared with current emissions. Under a scenario where fossil fuel use continues to increase at current rates through the middle of the century, winter carbon dioxide emissions from permafrost would rise by 41%.

Reposted here because it is a rather significant find about permafrost.

Abstract:
https://www.nature.com/articles/s41558-019-0592-8

Stuff that was bolded not long ago.

We predict that the PCF will change the arctic from a carbon sink to a source after the mid‐2020s


Well that failed.

Furthermore, there is high confidence that climate scenarios that involve mitigation (e.g. RCP4.5) will help to dampen the response of carbon emissions from the Arctic and boreal regions.


What really helps if you force the world onto that path. Or something even better.

Basically there is only one important scenario, the one we call the world.

We should go zero quicker and more coordinated and employ a bunch of cheap sensible carbon capture techniques ASAP which is ofc not going to happen.

The earlier 2020 date triggered me because one of the goals always was to prevent things like this from happening and now it is already here.

Eyeballing Mauna Loa CO2 anything over 370 is bad. So that is an interesting challenge.
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bluesky

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Re: Permafrost general science thread
« Reply #51 on: November 11, 2019, 10:37:43 AM »

Geophysical Research Letters

Research Letter  Open Access

Rapid CO2 Release From Eroding Permafrost in Seawater
G. Tanski  D. Wagner  C. Knoblauch  M. Fritz T. Sachs  H. Lantuit
First published: 15 October 2019
https://doi.org/10.1029/2019GL084303
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Abstract
Permafrost is thawing extensively due to climate warming. When permafrost thaws, previously frozen organic carbon (OC) is converted into carbon dioxide (CO2) or methane, leading to further warming. This process is included in models as gradual deepening of the seasonal non‐frozen layer. Yet, models neglect abrupt OC mobilization along rapidly eroding Arctic coastlines. We mimicked erosion in an experiment by incubating permafrost with seawater for an average Arctic open‐water season. We found that CO2 production from permafrost OC is as efficient in seawater as without. For each gram (dry weight) of eroding permafrost, up to 4.3 ± 1.0 mg CO2 will be released and 6.2 ± 1.2% of initial OC mineralized at 4 °C. Our results indicate that potentially large amounts of CO2 are produced along eroding permafrost coastlines, onshore and within nearshore waters. We conclude that coastal erosion could play an important role in carbon cycling and the climate system

Rapid CO2 Release From Eroding Permafrost in Seawater
G. Tanski  D. Wagner  C. Knoblauch  M. Fritz T. Sachs  H. Lantuit
First published: 15 October 2019
https://doi.org/10.1029/2019GL084303
« Last Edit: November 11, 2019, 03:23:36 PM by bluesky »

kassy

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Re: Permafrost general science thread
« Reply #52 on: November 12, 2019, 02:09:47 PM »
Thanks!

From the PLS:
A slow and continuous thaw is currently used in models to project future greenhouse gas release from permafrost. Yet along the rapidly eroding coastlines of the Arctic Ocean, which make up 34% of the Earth's coastlines, whole stretches of the coast simply collapse, sink or slide into the ocean, including the previously frozen organic carbon.

Bolded: i would never have guessed it was that much.
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kassy

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Re: Permafrost general science thread
« Reply #53 on: Today at 01:22:09 PM »
Shrubbier tundra likely accelerates permafrost thawing, study finds
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Areas with dwarf birch saw faster snow melt and deeper ground thawing

...

While their impact varies, a paper recently published in the journal, Arctic Science, found areas with birch shrubs had longer snow-free periods, in turn accelerating the thawing of the ground below.

"We discovered that the date at which the snow melts is a key driver in how deep the ground will thaw in the summer," said Evan Wilcox, a geography PhD candidate at Wilfrid Laurier University and the paper's lead author.

"Areas where the shrubs protrude through [the snow], the snow melts on average a week earlier," he said. Taller shrubs paired with warmer air temperatures will likely result in more permafrost thawing, he said.

for details see:
https://www.cbc.ca/news/canada/north/arctic-tundra-permafrost-thaw-shrub-1.5359354

and

Tundra shrub expansion may amplify permafrost thaw by advancing snowmelt timing

https://www.nrcresearchpress.com/doi/10.1139/as-2018-0028#.Xc6YDVdKjct
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