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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: November 15, 2019, 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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gerontocrat

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Re: Permafrost general science thread
« Reply #54 on: December 11, 2019, 08:58:09 PM »
The essay linked below is in the NOAA 2019 Arctic Report Card https://arctic.noaa.gov/Report-Card/Report-Card-2019
Basically, winter CO2 emissions grossly underestimated and more than CO2 capture in the Summer by 0.6 petagrams of CARBON per annum.

To us simple people it is 0.6 x 3.67 = 2.2 GT of CO2 - a significant amount meaning a carbon sink is a actually a carbon emitter.

Extracts.....
https://arctic.noaa.gov/Report-Card/Report-Card-2019/ArtMID/7916/ArticleID/844/Permafrost-and-the-Global-Carbon-Cycle
Permafrost and the Global Carbon Cycle

Quote
Highlights
- Northern permafrost region soils contain 1,460-1,600 billion metric tons of organic carbon, about twice as much as currently contained in the atmosphere.
- This pool of organic carbon is climate-sensitive. Warming conditions promote microbial conversion of permafrost carbon into the greenhouse gases carbon dioxide and methane that are released to the atmosphere in an accelerating feedback to climate warming.
- New regional and winter season measurements of ecosystem carbon dioxide flux independently indicate that permafrost region ecosystems are releasing net carbon (potentially 0.3 to 0.6 Pg C per year) to the atmosphere.
- These observations signify that the feedback to accelerating climate change may already be underway.

Introduction
The Arctic continues to warm at a rate that is currently twice as fast as the global average (see essay Surface Air Temperature). Warming is causing perennially-frozen ground (permafrost) to thaw, with permafrost in many locations currently reaching record high temperatures (Biskaborn et al. 2019). Organic carbon contained in soils of the permafrost region represent a climate-sensitive carbon reservoir that is affected by warming air and ground temperatures and permafrost thaw....

The northern permafrost region holds almost twice as much carbon as is currently in the atmosphere. Additional net releases of carbon dioxide (CO2) and methane (CH4) to the atmosphere as a result of warming and faster microbial decomposition of permafrost carbon have the potential to accelerate climate warming. ....

Permafrost carbon pools: How much permafrost carbon is available to release into the atmosphere?
The new, best mean estimate of the amount of organic carbon stored in the northern permafrost region is 1,460-1,600 petagrams (Pg; 1 Pg = 1 billion metric tons) (Hugelius et al. 2014; Schuur et al. 2015). Of this inventory, 65-70% (1,035 ± 150 Pg) of the carbon is within the surface layer (0-3 m depth) (Fig. 1). Soils in the top 3 m of the rest of Earth's biomes (excluding Arctic and boreal biomes) contain 2,050 Pg of organic carbon (Jobbagy and Jackson 2000). The soil carbon from the northern circumpolar permafrost region adds another 50% to this 3-m inventory, even though it occupies only 15% of the total global soil area (Schuur et al. 2015).

Ecosystem-atmosphere carbon exchange: Is the Arctic currently releasing additional net carbon dioxide emissions to the atmosphere?
....
A new comprehensive synthesis study of non-summer ecosystem CO2 fluxes across the circumpolar region showed that carbon release during the Arctic winter was 2 to 3 times higher than previously estimated from ground-based measurements (Fig. 3) (Natali et al. 2019). This circumpolar estimate suggests that carbon release in the cold season offsets net carbon uptake during the growing season (derived from models) such that the region as a whole could already be a source of 0.6 Pg C per year to the atmosphere.
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TerryM

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Re: Permafrost general science thread
« Reply #55 on: December 12, 2019, 03:07:21 AM »
^^
Northern Ontario's vast permafrost regions seem destined to emit large quantities of GHGs regardless of what steps we take.  To the east of James Bay in Northern Quebec, the flooding of an area twice the size of Scotland with relatively warm water will speed the melting of the permafrost layers and increase GHG emissions year round. The Eastmain Hydro project is being expanded and will again be the world's largest producer of hydroelectric power.
These emissions don't appear on your charts - yet.


The warmest, most southerly permafrost regions are presently the largest emitters, but as the Arctic warms the melting regions will expand, and emissions will expand with them. The last time this occurred we had turtles, alligators and primates living year round on Ellesmere Island. Six months without insolation apparently wasn't enough to freeze them out.


I question whether primates will survive this accelerated warming.
Terry

Juan C. García

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Re: Permafrost general science thread
« Reply #56 on: December 13, 2019, 11:22:25 AM »
Quote
The Arctic may have crossed key threshold, emitting billions of tons of carbon into the air, in a long-dreaded climate feedback

The Arctic is undergoing a profound, rapid and unmitigated shift into a new climate state, one that is greener, features far less ice and emits greenhouse gas emissions from melting permafrost, according to a major new federal assessment of the region released Tuesday.

The consequences of these climate shifts will be felt far outside the Arctic in the form of altered weather patterns, increased greenhouse gas emissions and rising sea levels from the melting Greenland ice sheet and mountain glaciers.

The findings are contained in the 2019 Arctic Report Card, a major federal assessment of climate change trends and impacts throughout the region. The study paints an ominous picture of a region lurching to an entirely new and unfamiliar environment.

Especially noteworthy is the report’s conclusion that the Arctic already may have become a net emitter of planet-warming carbon emissions due to thawing permafrost, which would only accelerate global warming.
https://www.washingtonpost.com/weather/2019/12/10/arctic-may-have-crossed-key-threshold-emitting-billions-tons-carbon-into-air-long-dreaded-climate-feedback/?wpisrc=al_environment__alert-hse&wpmk=1
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

ArcticMelt2

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nanning

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Re: Permafrost general science thread
« Reply #58 on: December 14, 2019, 11:10:22 AM »
^^
I don't understand that presentation.
It reads:

5% - 15% (vulnerable fraction of permafrost)
146 - 160 billion tons (emissions)

160?

15% should be 3*146 = 438GT I think. A 'bit' more than 160GT.

Or 5% should be 160/3 = 53GT. A 'bit' less than 146GT.

That's a lot of carbon (75ppm in the presentation) and the "5% - 15%" may well increase to "5% - 20%" or more in the future with new and better understanding.
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kassy

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Re: Permafrost general science thread
« Reply #59 on: December 14, 2019, 11:40:17 AM »
The slide could be clearer. See the report card quote in #54 above.

Northern permafrost region soils contain 1,460-1,600 billion metric tons of organic carbon

So that number is the total in play but working out the emissions is not straightforward.
I think the 5-15% is also a base input.

It would be nice to have a name of a scientist or an article to go with the slide (not a Twitter fan but looking at the feed it seems to come from the Report Card so delve into that to see how they arrive at the numbers.
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gerontocrat

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Re: Permafrost general science thread
« Reply #60 on: December 14, 2019, 12:03:27 PM »
^^
I don't understand that presentation.
It reads:

5% - 15% (vulnerable fraction of permafrost)
146 - 160 billion tons (emissions)

160?

15% should be 3*146 = 438GT I think. A 'bit' more than 160GT.

Or 5% should be 160/3 = 53GT. A 'bit' less than 146GT.

That's a lot of carbon (75ppm in the presentation) and the "5% - 15%" may well increase to "5% - 20%" or more in the future with new and better understanding.
Total Arctic Permafrost (on land) is estimated to contain 1400 to 1600 GT of CARBON.

The 140-160 GT guess of possible carbon emissions from Arctic permafrost to 2100 in the presentation is 10%, i.e. the mid-point of 5% to 15%.

If released as CO2 that is 160 GT of carbon x 3.67 = 590 GT of CO2.

1 ppm of atmospheric CO2 = 7.81 GT

So 160 GT of carbon released into the atmosphere equates to 75 ppm.

But that ignores any increase in absorption by the carbon sinks (currently 50%)
BUT who knows what the future of carbon sinks will be? Most of the news is not good about either the land or the ocean sinks.

The presentation also does not consider possible CO2 and CH4 emissions from undersea permafrost (e.g. from the shallow East Siberian Arctic Shelf).

A recent paper suggests that current emissions may already be at about 2.2 GT of CO2 per annum, i.e. if continued at that rate to 2100 = 176 billion GT of CO2. Obviously AGW + polar amplification would increase that rate substantially.
(see post #54 by me above)
Link is https://arctic.noaa.gov/Report-Card/Report-Card-2019/ArtMID/7916/ArticleID/844/Permafrost-and-the-Global-Carbon-Cycle
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nanning

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Re: Permafrost general science thread
« Reply #61 on: December 14, 2019, 04:37:35 PM »
I haven't read the Report Card, sorry. I've lost my interest in details I think.
Thank you for explaining and for your view gerontocrat.

Quote from: kassy
It would be nice to have a name of a scientist or an article to go with the slide

That would've been nice in retrospect (I thought it was an error).
And thank you for your response.
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wdmn

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Re: Permafrost general science thread
« Reply #62 on: December 19, 2019, 12:41:15 AM »
The Arctic’s grand reveal

https://news.uaf.edu/the-arctics-grand-reveal/

"University of Alaska Fairbanks scientists presented their work at the American Geophysical Union’s fall meeting in San Francisco this week.

...

Most experts suggest permafrost thaw will continue and even speed up as we go into the next century.

However, calculated rates of thaw may be far lower than what will really happen. According to Farquharson, a key accelerating factor in permafrost thaw has been dramatically underestimated.

“It’s the Arctic’s ‘grand reveal,’” Farquarson said. “We thought we saw what was happening, then it really stepped out from behind the curtain.”

This factor is called talik, thawed zones in permafrost areas.

The mixture of wet, frigid dirt is commonly associated with Arctic thermokarst lakes that form when enough ice-rich permafrost thaws to create a body of water.

The talik beneath these lakes significantly contributes to the thawing process. Just as icewater melts faster than a lone cube of ice, the waterlogged ground accelerates thawing of the permafrost around it.

Normally talik has been thought of as limited to the areas just below and around thermokarst lakes, but Farquharson’s work shows they are much more extensive.

Farquharson and her collaborators, including Vladimir Romanovsky, also at the Geophysical Institute, observed substantial evidence from 28 sites across Alaska showing these taliks are larger, and extend deeper in the ground, than previously thought — even in many areas scientists didn’t know it existed.

This could have dramatic effects on permafrost, making previous thaw forecasts and estimates of subsequent carbon release pale in comparison to what is coming.

“You look at your lake distribution of taliks and how much of the landscape that accounts for, and then you take that number and you spread it across pretty much the entire landscape in Interior Alaska,” she said.

“We’re going to basically change the calculations for global carbon emissions.”

...

Her reserved tone hid a bombshell message — by 2035 permafrost thaw may continue on its own, disregarding the processes that have kept it frozen for thousands of years."

vox_mundi

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Re: Permafrost general science thread
« Reply #63 on: December 19, 2019, 02:44:48 AM »
Thawing Permafrost Affecting Northern Alaska's Land-to-Ocean River Flows
https://phys.org/news/2019-12-permafrost-affecting-northern-alaska-land-to-ocean.html

A new analysis of the changing character of runoff, river discharge and other hydrological cycle elements across the North Slope of Alaska reveals significant increases in the proportion of subsurface runoff and cold season discharge, changes the authors say are "consistent with warming and thawing permafrost."

First author and lead climate modeler Michael Rawlins, associate professor of geosciences at the University of Massachusetts Amherst and associate director of its Climate Systems Research Center, says warming is expected to shift the Arctic from a surface water-dominated system to a groundwater-dominated system, with deeper water flow paths through newly thawed soils.

... The researchers observed significant increases in cold season discharge, such as 134% of the long-term average for the North Slope, and 215% in the Colville River basin, for example. They report a significant increase in the ratio of subsurface runoff to total runoff for the region and for 24 of the 42 study basins, with the change most prevalent across the northern foothills of the Brooks Range. They also observed a decline in terrestrial water storage, which they attribute to losses in soil ice that outweigh gains in soil liquid water storage. The timing of peak spring freshet discharge, the flow of snowmelt into the sea, also has shifted earlier by 4.5 days.



"Our model estimates of permafrost thaw are consistent with the notion that permafrost region ecosystems are shifting from a net sink to a net source of carbon," he says.

Open Access: Michael A. Rawlins et al, Changing characteristics of runoff and freshwater export from watersheds draining northern Alaska, The Cryosphere (2019)
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kassy

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Re: Permafrost general science thread
« Reply #64 on: December 19, 2019, 03:24:16 PM »
Thanks for the articles.

Earlier but related publication by Farquharson

We find that observed maximum thaw depths at all sites are already regularly exceeding modeled future thaw depths for 2090 under IPCC RCP 4.5. Our data show that very cold permafrost (<−10 °C) at high latitudes is highly vulnerable to rapid near‐surface permafrost degradation due to climate change.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL082187
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Ken Feldman

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Re: Permafrost general science thread
« Reply #65 on: December 19, 2019, 07:51:27 PM »
While the news from the Arctic seems dire, keep in mind that in both the cases of the Alaskan tundra carbon emissions highlighted in the 2019 Arctic Report Card and the attention given to thermokarst emissions are based on a few measurements over a short period of time in smaller areas extrapolated to the entire globe. 

Here are the details from the Arctic Report Card.

https://arctic.noaa.gov/Report-Card/Report-Card-2019/ArtMID/7916/ArticleID/844/Permafrost-and-the-Global-Carbon-Cycle

Quote
Another approach to this same question is to measure changes in atmospheric greenhouse gas concentrations and to separate out contributions from different sources. Given the extent of fossil fuel carbon emissions, it remains a challenge to quantify and separate the effect of ecosystem carbon exchange, but regional atmospheric measurement campaigns can help to focus in on local influences (Parazoo et al. 2016). Recent measurements of atmospheric greenhouse gas concentrations over Alaska by NASA aircraft have been used to the estimate the net regional impact on the atmosphere by those Arctic and boreal ecosystems for 2012 to 2014 (Commane et al. 2017). This recent NASA campaign was able to provide important insight into the aggregate influence of the carbon exchange for the Alaska permafrost region, across tundra, boreal forests, and wetland/lake/freshwater ecosystems as a whole. During this three-year time period, the tundra region of Alaska was found to be a consistent net CO2 source to the atmosphere, whereas the boreal forest region was either neutral or a net CO2 sink. The boreal forest region exhibited larger interannual variability due both to changes in the balance of photosynthesis and respiration and to the amount of combustion emissions by wildfire.

The Alaska study region as a whole was estimated to be a net carbon source of 0.025 ± 0.014 Pg C per year averaged over the land area of both tundra and boreal forest regions for the three-year study period. If this Alaskan region (1.6 × 106 km2) was representative of the entire northern circumpolar permafrost region soil area (17.8 × 106 km2), this amount would be equivalent to a circumpolar net source of 0.3 Pg C per year. Historically (over hundreds to thousands of years), the Arctic region was accumulating carbon in soils and vegetation and thus was acting as a net sink of atmospheric CO2. Assuming this three-year snapshot provided by NASA aircraft monitoring is indicative of the Arctic's current physical and biological environment, a significant and major threshold has been crossed in the high latitude region whereas the aggregate effect of terrestrial ecosystems is now contributing to, rather than slowing, climate change.

Alaska has a large and active oil and gas industry, which most of the Arctic doesn't.  The oil and gas industry is notorious for having a lot of methane leaks and flaring (which enhances both CH4 and CO2 concentrations in the oil fields).

While the report card does acknowledge that global warming may increase the growing season and thus increase the sinks, the calculations that lead to the headline grabbing results didn't include the effects of the increased growing season.

Another impact of global warming is that the area of tundra (the portion of the Arctic that is increasing emissions) is shrinking and the area of the boreal forest is increasing.  The Report Card states that the boreal forests are either neutral or sinks.

Here's a 2016 paper on the change in the Arctic from tundra to forests.

https://www.researchgate.net/profile/Matthias_Forkel/publication/291346720_Enhanced_seasonal_CO2_exchange_caused_by_amplified_plant_productivity_in_northern_ecosystems/links/573ed08c08ae9f741b31ef1d.pdf

Quote
Enhanced seasonal CO2 exchange caused by amplified plant productivity in northern ecosystems
Matthias Forkel,1*†Nuno Carvalhais,1,2*Christian Rödenbeck,1Ralph Keeling,3Martin Heimann,1,4Kirsten Thonicke,5Sönke Zaehle,1Markus Reichstein1,6

Atmospheric monitoring of high northern latitudes (above 40°N) has shown an enhanced seasonal cycle of carbon dioxide (CO2) since the 1960s, but the underlying mechanisms are not yet fully understood. The much stronger increase in high latitudes relative to low ones suggests that northern ecosystems are experiencing large changes in vegetation and carbon cycle dynamics. We found that the latitudinal gradient of the increasing CO2 amplitude is mainly driven by positive trends in photosynthetic carbon uptake caused by recent climate change and mediated by changing vegetation cover in northern ecosystems. Our results underscore the importance of climate–vegetation–carbon cycle feedbacks at high latitudes; moreover, they indicate that in recent decades, photosynthetic carbon uptake has reacted much more strongly to warming than have carbon release processes.

Quote
A variety of factors may contribute to the CO2amplitude trend. Arctic and boreal regions have experienced strong warming in recent decades(6), and a“greening” trend has been detected from satellites, indicating enhanced plant growth(7,8) (Fig. 1, A and B). These satellite observations are confirmed by ground observations showing increases in shrub coverage in the tundra (9),tree growth along the tundra–boreal forest transition zone (10), and deciduous tree cover from recovery after severe boreal forest fires (11). Additionally, various estimates show positive trends in both annual amplitudes and annual totals of GPP (12,13) and in net biome productivity (NBP)(14)in northern ecosystems (Fig.1,CandD).The intensification of agriculture in the midlatitudes also likely contributes to the CO2 amplitude trends (15,16). These multiple observational signals point to amplified plant productivity as a likely cause of the increase in CO2 amplitude(1,3,7,17). Nonetheless, a quantitative explanation of the amplitude trends is still lacking. Current Earth system models consistently under-estimate the CO2 amplitude trend (4) and its gradient with latitude, which suggests that these models are missing or underrepresenting key processes (18).

Quote
« Last Edit: December 19, 2019, 07:57:00 PM by Ken Feldman »

Ken Feldman

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Re: Permafrost general science thread
« Reply #66 on: December 19, 2019, 08:48:14 PM »
The following paper provides a good overview of why there is so much uncertainty about whether Arctic tundra regions are sources or sinks.  And it indicates that in 2014 and 2015, the Lena River floodplain was a sink for carbon emissions.

https://www.biogeosciences.net/16/2591/2019/

Quote
Rößger, N., Wille, C., Holl, D., Göckede, M., and Kutzbach, L.: Scaling and balancing carbon dioxide fluxes in a heterogeneous tundra ecosystem of the Lena River Delta, Biogeosciences, 16, 2591–2615, https://doi.org/10.5194/bg-16-2591-2019, 2019.

Abstract

The current assessments of the carbon turnover in the Arctic tundra are subject to large uncertainties. This problem can (inter alia) be ascribed to both the general shortage of flux data from the vast and sparsely inhabited Arctic region, as well as the typically high spatiotemporal variability of carbon fluxes in tundra ecosystems. Addressing these challenges, carbon dioxide fluxes on an active flood plain situated in the Siberian Lena River Delta were studied during two growing seasons with the eddy covariance method. The footprint exhibited a heterogeneous surface, which generated mixed flux signals that could be partitioned in such a way that both respiratory loss and photosynthetic gain were obtained for each of two vegetation classes. This downscaling of the observed fluxes revealed a differing seasonality in the net uptake of bushes (−0.89 µmol m−2 s−1) and sedges (−0.38 µmol m−2 s−1) in 2014. That discrepancy, which was concealed in the net signal, resulted from a comparatively warm spring in conjunction with an early snowmelt and a varying canopy structure. Thus, the representativeness of footprints may adversely be affected in response to prolonged unusual weather conditions. In 2015, when air temperatures on average corresponded to climatological means, both vegetation-class-specific flux rates were of similar magnitude (−0.69 µmol m−2 s−1). A comprehensive set of measures (e.g. phenocam) corroborated the reliability of the partitioned fluxes and hence confirmed the utility of flux decomposition for enhanced flux data analysis. This scrutiny encompassed insights into both the phenological dynamic of individual vegetation classes and their respective functional flux to flux driver relationships with the aid of ecophysiologically interpretable parameters. For comparison with other sites, the decomposed fluxes were employed in a vegetation class area-weighted upscaling that was based on a classified high-resolution orthomosaic of the flood plain. In this way, robust budgets that take the heterogeneous surface characteristics into account were estimated. In relation to the average sink strength of various Arctic flux sites, the flood plain constitutes a distinctly stronger carbon dioxide sink. Roughly 42 % of this net uptake, however, was on average offset by methane emissions lowering the sink strength for greenhouse gases. With growing concern about rising greenhouse gas emissions in high-latitude regions, providing robust carbon budgets from tundra ecosystems is critical in view of accelerating permafrost thaw, which can impact the global climate for centuries.

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The Arctic north of 60∘ N latitude has warmed at a rate of 1.36 ∘C per century since 1875, i.e. roughly twice as fast as the global average (Masson-Delmotte et al., 2013). And this rapid warming trend is projected to continue (Collins et al., 2013). Due to ambiguous model results and their large confidence intervals, it currently remains unclear whether the permafrost areas maintain their sink function or convert into a carbon source in the future (Heimann and Reichstein, 2008; Schuur et al., 2015). These uncertainties do not only arise from the limited knowledge of the physical thawing rates, the fraction of released carbon after thawing and the timescales of release but also from the general shortage of flux data in Arctic ecosystems (Ciais et al., 2013). The scarce data availability particularly applies to the extensive Siberian tundra, which covers around 3 million km2, i.e. more than half of northern high-latitude tundra ecosystems (Chapin et al., 2005; Sachs et al., 2010). The low density of flux observation sites is due to both harsh environmental conditions as well as challenging logistics in these remote and sparsely inhabited areas that are often without line power. Consequently, current estimates of the tundra's sink strength for carbon dioxide are associated with large uncertainties: −103±193 Tg C yr−1 (McGuire et al., 2012). The same issue applies to estimates that indicate a shift to a source for carbon dioxide: 462±378 Tg C yr−1 (Belshe et al., 2013). The refinement of these macroscale estimates and the reduction of their uncertainties can be achieved via providing both more flux budgets (in particular from the Siberian tundra) and more reliable information on the variation in habitats (e.g. bogs, fens,) plus their associated surface heterogeneities (e.g. tussocks, hummocks).

Tundra ecosystems are frequently characterised by a pronounced vegetation patchiness with sharply defined boundaries between different vegetation classes (Shaver et al., 2007). Besides vegetation, surface classifications can also be based on differences in soil moisture, snow cover, permafrost features or combinations of them (Fox et al., 2008; Virkkala et al., 2018). The consequently high spatial variability in carbon fluxes complicates the estimation of robust carbon budgets that are accurate and precise. The omission of accounting for the spatial distribution of different surface types is likely to lead to incorrect budgets (Oechel et al., 1998). Therefore, an improved understanding of the effects of surface heterogeneity on these budgets, e.g. through a better characterisation of both spatial flux variability as well as associated key factors such as vegetation composition and structure, is necessary (Kade et al., 2012; Kwon et al., 2006). For quantifying vegetation properties, NDVI (normalised difference vegetation index), LAI (leaf area index) and foliar nitrogen content have been found suitable (Marushchak et al., 2013; Shaver et al., 2013). All of these predictors can be estimated by remote sensing, thereby neglecting the patchy nature of tundra ecosystems, but also offering the potential for macroscale modelling of both carbon dioxide budgets plus their prospective alterations through climate change. Such assessments are based on biome-level monitoring of the global warming-induced impacts on Arctic vegetation such as growing season prolongation as well as expansion of plant's growing range and size, e.g. the enhanced growth of shrubs and their northward migration into typical graminoid tundra ecosystems (Jia et al., 2009; Sweet et al., 2015). On the other side, microscale observations are crucial in order to reflect the individual biogeochemical dynamics in the mosaic of vegetation patches. The direct appraisal of the vegetation's responses to global warming through field surveys on the plant community level involves aspects such as enhanced primary productivity, deeper rooting depths, as well as augmented ground shading and snow accumulation trough taller growth forms (Myers-Smith et al., 2011; Sitch et al., 2007).

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3.5 Greenhouse gas balances

The evaluation of the flood plain's sink/source strength for greenhouse gases required the corresponding methane emission budgets and their conversion to carbon dioxide equivalents (Rößger et al., 2019a). Despite methane's minor percentage of roughly 3 % in the entire greenhouse gas exchange (specified in molar units), its carbon dioxide equivalents diminished the greenhouse gas sink strength (given by the carbon dioxide net uptake) by half in 2014 and by one-third in 2015. Accordingly, the greenhouse gas balances specify that the flood plain formed a moderate sink of −2.21±0.61
 mol CO2 eq. m−2 and a stronger sink of −3.81±0.74

 mol CO2 eq. m−2 during the warm season in 2014 and 2015, respectively (Table 2). The lower sink strength in 2014 was a result of a reduced carbon dioxide net uptake rather than an augmented methane efflux. And this reduced carbon dioxide net uptake in turn was caused by a lowered net uptake in vegetation class 2 that effectively counteracted the elevated early season net uptake in vegetation class 1. This class constituted a stronger greenhouse gas sink than vegetation class 2 in both years, which is mainly due to the fact that methane emissions were only present in vegetation class 2. Since these emissions hardly changed between the years along with the negligible methane release in vegetation class 1, the interannual variability in the greenhouse gas sink strength was governed by the carbon dioxide net uptake.

These balances are the first greenhouse gas budgets of a flood plain in the Lena River Delta. Based on these budgets, the sink strength of the adjacent river terrace, where another eddy covariance system has been in operation for many years, could finally be put in context within the domain of the Lena River Delta (Table 2). In 2014 and 2015, the flood plain sequestered per square metre roughly 20 % and 60 % more carbon dioxide, respectively, but it also emitted approximately 70 % more methane. Hence, the flood plain constituted a sink for greenhouse gases that resembled (2014) or was 1.5 times (2015) the sink strength of the polygonal tundra on the river terrace.

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4.5 Comparison of the budgets with other Arctic sites

Across various Arctic flux sites, the flood plain of Samoylov Island exhibits a carbon dioxide sink strength that is distinctly greater than the average (Fig. 1 and Table 3). This aspect appears noteworthy when local conditions are taken into consideration: the mean net radiation during the growing season is lower than for most Arctic sites, and the underlying permafrost displays one of the lowest ground temperatures in the world (Boike et al., 2013; Obu et al., 2018; Romanovsky et al., 2010). The diminishing effects of these climate factors are counterbalanced by the deposition of nutrients in the course of spring flooding (van Huissteden et al., 2005). Among the three great Siberian rivers draining into the Arctic Ocean (Ob, Yenisei, Lena), the Lena River ranks first in terms of total suspended matter (Cauwet and Sidorov, 1996). A large portion of this matter is transported during the annual spring flood, thereby regularly mitigating the nutrient limitation that affects many Arctic ecosystems (Beermann et al., 2014; Fedorova et al., 2015).

More specifically, the net uptake of the flood plain on Samoylov Island is distinctly weaker compared to flood plains of the Siberian rivers Kolyma and Indigirka (Kittler et al., 2017; Parmentier et al., 2011). Other Siberian sites encompass Seida and Lavrentiya, which exhibit a similar and stronger net uptake, respectively (Marushchak et al., 2013; Zamolodchikov et al., 2003). Furthermore, the flood plain's net uptake is considerably stronger than budgets of high Arctic sites in Svalbard, Greenland and Canada (Lafleur et al., 2012; López-Blanco et al., 2017; Lüers et al., 2014; Lund et al., 2012). In comparison with sites in either the low Arctic or sub-Arctic, no general conclusions can be drawn, which is likely due to the ubiquitously high spatiotemporal flux variability in the Arctic region. Also, no uniform picture emerges in comparison to Scandinavian peatlands (Aurela et al., 2002, 2009; Fox et al., 2008). Compared with sites in the northern part of the north slope of Alaska, the flood plain exhibits a substantially stronger net uptake (Oechel et al., 2014; Raz-Yaseef et al., 2017); in the southern part, however, similar net uptakes seem to prevail (Euskirchen et al., 2016).


kassy

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Re: Permafrost general science thread
« Reply #67 on: December 24, 2019, 12:33:57 PM »
ALSR posted an interesting article on the situation near Barrow:

The linked reference provides field evidence that aquatic plants in arctic tundra wetlands is a major source of methane emissions, and will likely serve as a positive feedback mechanism with continued global warming (the AR5 & CMIP5 projections do not account for this source of methane):

C G Andresen, M J Lara, C E Tweedie & V L Lougheed (19 August 2016) "Rising Plant-mediated Methane Emissions from Arctic Wetlands", Global Change Biology, DOI: 10.1111/gcb.13469

http://onlinelibrary.wiley.com/doi/10.1111/gcb.13469/abstract

Abstract: "Plant-mediated CH4 flux is an important pathway for land-atmosphere CH4 emissions but the magnitude, timing, and environmental controls, spanning scales of space and time, remain poorly understood in arctic tundra wetlands, particularly under the long term effects of climate change. CH4 fluxes were measured in situ during peak growing season for the dominant aquatic emergent plants in the Alaskan arctic coastal plain, Carex aquatilis and Arctophila fulva, to assess the magnitude and species-specific controls on CH4 flux. Plant biomass was a strong predictor of A. fulva CH4 flux while water depth and thaw depth were co-predictors for C. aquatilis CH4 flux. We used plant and environmental data from 1971-72 from the historic International Biological Program (IBP) research site near Barrow, Alaska, which we resampled in 2010-13, to quantify changes in plant biomass and thaw depth, and used these to estimate species-specific decadal-scale changes in CH4 fluxes. A ~60% increase in CH4 flux was estimated from the observed plant biomass and thaw depth increases in tundra ponds over the past 40 years. Despite covering only ~5% of the landscape, we estimate that aquatic C. aquatilis and A. fulva account for two-thirds of the total regional CH4 flux of the Barrow Peninsula. The regionally observed increases in plant biomass and active layer thickening over the past 40 years not only have major implications for energy and water balance, but have significantly altered land-atmosphere CH4 emissions for this region, potentially acting as a positive feedback to climate warming."
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vox_mundi

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Re: Permafrost general science thread
« Reply #68 on: January 08, 2020, 10:07:48 PM »
Sea-Ice-Free Arctic Increases Permafrost Vulnerablety to Thawing
https://m.phys.org/news/2020-01-sea-ice-free-arctic-permafrost-vulnerable.html

... The new research relies on challenging field work to discover and explore Siberian caves. Caves are powerful recorders of periods when permafrost was absent in the past. Stalagmites, stalactites and flowstones can only form when there is liquid water, and therefore not when overlying land is permanently frozen. The presence of stalagmites in caves under present permafrost thus demonstrate periods when permafrost was absent in the past.

Development of new approaches to date stalagmites using measurements of natural uranium and lead, allow dating of the recovered stalagmites—and therefore of periods of permafrost absence—for the last one and a half million years. Stalagmites grew intermittently from 1,500,000 to 400,000 years ago, and have not grown for the last 400,000 years. The timing of stalagmite formation, and therefore absence of permafrost, do not relate simply to global temperatures in the past but are notably more common when the Arctic Ocean was free of summer sea-ice.

This study shows that several processes may lead to the relationship between Arctic sea-ice and permafrost. The absence of sea ice leads to an increase in heat and moisture transfer from ocean to atmosphere and therefore to warmer air transported far overland into Siberia. Moisture transport also increases snow fall over Siberia during the autumn months. This blanket of snow insulates the ground from the extreme cold of winters leading to an increase in average annual ground temperatures, destabilising the permafrost. Consequently, in regions with increased snow cover and insulation, permafrost will start to thaw, releasing carbon dioxide that was trapped for millennia.

A. Vaks, G. Henderson, et.al. Palaeoclimate evidence of vulnerable permafrost during times of low sea ice, Nature, 2020
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kassy

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Re: Permafrost general science thread
« Reply #69 on: January 12, 2020, 10:22:05 PM »
Changing characteristics of runoff and freshwater export from watersheds draining northern Alaska

The quantity and quality of river discharge in Arctic regions is influenced by many processes including climate, watershed attributes and, increasingly, hydrological cycle intensification and permafrost thaw. We used a hydrological model to quantify baseline conditions and investigate the changing character of hydrological elements for Arctic watersheds between Utqiagvik (formerly known as Barrow)) and just west of Mackenzie River over the period 1981–2010. A synthesis of measurements and model simulations shows that the region exports 31.9 km3 yr−1 of freshwater via river discharge, with 55.5 % (17.7 km3 yr−1) coming collectively from the Colville, Kuparuk, and Sagavanirktok rivers. The simulations point to significant (p<0.05) increases (134 %–212 % of average) in cold season discharge (CSD) for several large North Slope rivers including the Colville and Kuparuk, and for the region as a whole. A significant increase in the proportion of subsurface runoff to total runoff is noted for the region and for 24 of the 42 study basins, with the change most prevalent across the northern foothills of the Brooks Range. Relatively large increases in simulated active-layer thickness (ALT) suggest a physical connection between warming climate, permafrost degradation, and increasing subsurface flow to streams and rivers. A decline in terrestrial water storage (TWS) is attributed to losses in soil ice that outweigh gains in soil liquid water storage. Over the 30-year period, the timing of peak spring (freshet) discharge shifts earlier by 4.5 d, though the time trend is only marginally (p=0.1) significant. These changing characteristics of Arctic rivers have important implications for water, carbon, and nutrient cycling in coastal environments.

Rawlins, M. A., Cai, L., Stuefer, S. L., and Nicolsky, D.: Changing characteristics of runoff and freshwater export from watersheds draining northern Alaska, The Cryosphere, 13, 3337–3352, https://doi.org/10.5194/tc-13-3337-2019, 2019.

https://www.the-cryosphere.net/13/3337/2019/
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TerryM

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Re: Permafrost general science thread
« Reply #70 on: January 13, 2020, 11:50:46 PM »
Today my canoe club issued a flood warning for one of the major tributaries to the Grand River.


This is the time for towering snow banks, those that melt into our Spring floods.


Who canoes in January in Canada?
Terry

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Re: Permafrost general science thread
« Reply #71 on: January 14, 2020, 04:15:36 AM »
@Terry

Paddle to the Sea starts his journey when there's still snow on the ground, but I think it's mid-April.



Stay dry!

TerryM

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Re: Permafrost general science thread
« Reply #72 on: January 17, 2020, 05:54:31 AM »
^^
Yea
It's a great flick!


Terry

kassy

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Re: Permafrost general science thread
« Reply #73 on: January 28, 2020, 02:52:00 PM »
Rewilding the Arctic could stop permafrost thaw and reduce climate change risks

The wide-scale introduction of large herbivores to the Arctic tundra to restore the ‘mammoth steppe’ grassland ecosystem and mitigate global warming is economically viable, suggests a new paper from the University of Oxford.

http://www.ox.ac.uk/news/2020-01-27-rewilding-arctic-could-stop-permafrost-thaw-and-reduce-climate-change-risks

You might remember the story about Pleistocene Park in Russia which is also referenced in the story. This research is about scaling that up:

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Natural climate solutions (NCS) in the Arctic hold the potential to be implemented at a scale able to substantially affect the global climate. The strong feedbacks between carbon-rich permafrost, climate and herbivory suggest an NCS consisting of reverting the current wet/moist moss and shrub-dominated tundra and the sparse forest–tundra ecotone to grassland through a guild of large herbivores. Grassland-dominated systems might delay permafrost thaw and reduce carbon emissions—especially in Yedoma regions, while increasing carbon capture through increased productivity and grass and forb deep root systems. Here we review the environmental context of megafaunal ecological engineering in the Arctic; explore the mechanisms through which it can help mitigate climate change; and estimate its potential—based on bison and horse, with the aim of evaluating the feasibility of generating an ecosystem shift that is economically viable in terms of carbon benefits and of sufficient scale to play a significant role in global climate change mitigation.

https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0122
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kassy

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Re: Permafrost general science thread
« Reply #74 on: February 04, 2020, 02:45:09 PM »
Rapidly thawing permafrost could double carbon emissions

A new study has found that the abrupt thawing of permafrost in the Arctic will double the carbon emissions suggested by previous estimates.

Scientists at the University of Colorada at Boulder have analysed the permafrost regions towards the Earth's polar north, which is already dramatically altered by climate change.

...

The change in emissions between previous estimates and those in the new study comes from the researchers' distinguishing gradual permafrost thaw - which slowly releases the carbon stores - from abrupt thaws.

The issue is that 20% of the Arctic permafrost layer is rich in ice, meaning it is more susceptible to temperature changes and could thaw more rapidly.

Abrupt thaws are a large emitter of carbon, particularly carbon dioxide but also methane, which is an even more potent greenhouse gas.

According to the researchers, even though less than 5% of the Arctic permafrost is going to be rapidly thawing at any given time, emissions from that rapid thawing will equal the emissions from all of the other areas thawing more gradually.

Although there are a number of ways that abrupt permafrost thaw can happen, the results are always a dramatic change to the ecology.

for much more details see:
https://news.sky.com/story/rapidly-thawing-permafrost-could-double-carbon-emissions-11925962

or
https://phys.org/news/2020-02-arctic-permafrost-greater-role-climate.html

Article:
https://www.nature.com/articles/s41561-019-0526-0
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longwalks1

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Re: Permafrost general science thread
« Reply #75 on: February 04, 2020, 10:10:56 PM »
Primary article
 
Carbon release through abrupt permafrost thaw
DOI        https://doi.org/10.1038/s41561-019-0526-0

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However, in areas with excess ground ice, surface subsidence called thermokarst can occur during permafrost  degradation.  Abrupt  thaw  processes  such  as  thermo-karst have long been recognized as influential but are complex and understudied,  and  thus  are  insufficiently  represented  in  coupled  models14. While gradual thaw slowly affects soil by centimetres over decades, abrupt thaw can affect many metres of permafrost soil in periods of days to several years15.

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Data synthesis and first-order models  ...     Here, we describe the numerical, inventory models of initial thaw and ecosystem recovery and present details of the first-order estimates of abrupt thaw carbon release. The goal of our study was to compare the magnitude of emissions from abrupt thaw relative to gradual thaw under similar model  conditions.  To  achieve  this,  we  developed  a  simple,  unified  framework for exploring ecosystem carbon balance across a diverse set  of  abrupt  thaw  processes.  Our  first-order  inventory  method  is  similar  to  initial  assessments  of  land-use  carbon  emissions21,  and  was  used  to  simulate  changes  in  ecosystem  carbon  balance  during  the  initial  abrupt  thaw  stage,  as  well  as  longer-term  ecosystem  recovery (Fig. 1)

Several of their graphs extend from 1900 to 2300 a.d. with Y as  Net radiative forcing (W m2)   

TerryM

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Re: Permafrost general science thread
« Reply #76 on: February 05, 2020, 04:50:43 AM »
To limit temperatures to +1.50C we were told we needed to begin by lowering our emissions by 7.6% per year for the next 10 years.


Is there any indication of how much deeper we'll have to dig to accommodate these additional permafrost emissions?


In reality I've seen no appetite for cutting back on our use of fossil fuels, unless a short term profit is somehow to be had. BAU competes with Green BAU because no politician will suggest that any sacrifices need to be made until after he has safely transitioned to the private sector.


We stride bravely into a dystopian future without a thought that perhaps we are the problem.
Terry

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Re: Permafrost general science thread
« Reply #77 on: February 05, 2020, 05:42:31 AM »
You might remember the story about Pleistocene Park in Russia which is also referenced in the story.
I find the short mention a bit insulting to Sergey Zimov's life work: "The Pleistocene Park, a family-run grassland restoration project". His son Nikita Zimov is actually a coauthor of the paper.

https://en.wikipedia.org/wiki/Sergey_Zimov



Slightly older docu:
« Last Edit: February 05, 2020, 05:53:03 AM by Florifulgurator »
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kassy

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Re: Permafrost general science thread
« Reply #78 on: February 05, 2020, 11:11:04 AM »
Collapsing permafrost is transforming the Arctic’s waterways

...

It is critically important to realize that permafrost thaw will not stop once the global climate has stabilized, whether at the Paris Agreement limits of 1.5C or 2C, or at much higher levels. Even if anthropogenic carbon emissions are reduced over the coming decades, the concentration of carbon dioxide in the atmosphere will remain above pre-industrial levels for centuries — and likely millennia. Temperatures will also remain high.

As long as the global average temperature stays above the pre-industrial average, permafrost will continue to thaw, ground ice will melt, the land will subside, lakes and streams and freshwater ecosystems will change dramatically, with devastating effects on the peoples of the Arctic who have used these freshwater systems for generations.

Over the next year, governments will make decisions that will limit the increase in global temperature to below 1.5C or allow global warming to further increase to 2C or more. Our decisions will impact the Arctic and the globe for generations.

https://thenarwhal.ca/collapsing-permafrost-is-transforming-the-arctics-waterways/

A general article on permafrost.
Just quoted the conclusion because it bears repeating.
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Jim Hunt

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Re: Permafrost general science thread
« Reply #79 on: February 16, 2020, 11:52:19 AM »
An enquiry from Claire O’Neill via Twitter:

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Does anyone have good data on current permafrost melt rates? Sorry to ask so early on a Sunday!

Any suggestions?
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kassy

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Re: Permafrost general science thread
« Reply #80 on: February 16, 2020, 12:19:08 PM »
If you look at #50 and #74 #75 most work is about the carbon budget where we see that more carbon is released in winter months then is added as biomass over the summer.

The first post in this thread is a general study so might be closest to what you are looking for.

Some general stuff, no hard numbers but impressions from scientist doing field work:
https://www.nationalgeographic.com/environment/2019/08/arctic-permafrost-is-thawing-it-could-speed-up-climate-change-feature/
https://www.theguardian.com/environment/2019/jun/18/arctic-permafrost-canada-science-climate-crisis

ETA: Direct link to the paper in post #1
https://www.nature.com/articles/s41467-018-08240-4
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