More Fire and Anthrax for the Arctic: Study Finds 21 to 25 Percent of Northern Permafrost Will Thaw at Just 1.5 C of Warming
25
July, 2017
In
the far north, the land is rippling, trembling, subsiding, and
blowing up as greenhouse gasses are released from thawing frozen
soil. Meanwhile, old diseases are being released from thawing
carcasses and presenting a health hazard to locals.
(More
methane blowholes like this one in Yamal are likely as permafrost
thaw accelerates in the coming years and pockets of methane
explosively remove the land above. How extensive permafrost thaw
becomes is directly dependent on how much fossil fuel human societies
decide to burn. Image source: The
Siberian Times.)
Arctic
Carbon Feedbacks Accelerating
Carbon
feedbacks from the thawing permafrost are a serious concern. And they
should be.
There’s
about 1,400 billion tons of carbon locked away in that massive region
of frozen ground.
More than twice the amount humans have already emitted into the
atmosphere. And though frozen permafrost carbon stays locked away,
thawed permafrost carbon tends to become biologically active —
releasing into soils, the water and the air.
Already,
this thawing has generated a worrying effect. During the 20th
Century, it was estimated that about 500,000 tons of methane were
released from the Siberian land-based permafrost region. By 2003, as
this permafrost zone warmed, the annual rate of release was estimated
to be 3.8 million tons per year. And by 2013, with still greater
warming,
the
rate of release had grown to 17 million tons per year.
This compares to a global emission of methane from all sources —
both human and Earth System-based — of about 500 million tons per
year.
(Megaslump
craters like the one at Batagaika, formed by subsidence, are also a
result of permafrost thaw. Such features are likely to grow and
proliferate as the Earth warms and permafrost thaw expands.)
That’s
a thirty-fold acceleration in the rate of Siberian permafrost methane
emission over a little more than one generation. One that occurred as
temperatures rose to about 1 C above 1880s averages and into a range
not seen for about 150,000 years. It’s a warming that has
produced visible and concerning geophysical changes throughout the
Arctic permafrost environment. In Siberia, lands are subsiding even
as more and more methane and carbon dioxide are leeching out. And in
the Yamal region of Arctic Russia, temperatures warming into the
upper 80s (30 C+) during summer appear to have set off a rash of
methane eruptions from the soil even as ancient reindeer carcasses
release anthrax spores into the environment as they thaw. From a
report this week in The
Guardian:
Long dormant spores of the highly infectious anthrax bacteria frozen in the carcass of an infected reindeer rejuvenated themselves and infected herds of reindeer and eventually local people. More recently, a huge explosion was heard in June in the Yamal Peninsula. Reindeer herders camped nearby saw flames shooting up with pillars of smoke and found a large crater left in the ground. Melting permafrost was again suspected, thawing out dead vegetation and erupting in a blowout of highly flammable methane gas.
21
to 25.5 Percent of Northern Permafrost Set to Thaw over Next Two
Decades
In
total, 14
methane blow out craters are now identified throughout the Yamal
region.
A testament to the growing carbon feedback coming from previously
frozen and inactive stores.
(Permafrost
losses are likely to be quite considerable over the coming decades —
which is likely to produce serious knock-on effects for local and
global environments. But continued fossil fuel burning through end
Century produces more catastrophic results. Image source: Responses
and changes in the permafrost and snow water equivalent in the
Northern Hemisphere under a scenario of 1.5 C warming.)
But,
unfortunately, these kinds of weird, disturbing, and often dangerous
changes to northern environments are just a foreshadowing of more to
come. For
a recent scientific study has found that just 1.5 degrees Celsius
worth of warming will force between 21 and 25.5 percent of the
northern permafrost to thaw.
A process that is already underway, but that will continue to
accelerate with each 0.1 degree Celsius of additional warming. The
study found that the faster human atmospheric greenhouse gas
emissions build up, the more rapidly permafrost would thaw once the
1.5 C threshold was reached. Under a rapid human reduction of
greenhouse gasses (RCP
2.6 scenario),
permafrost thaw was reduced to 21 percent in the study. But under
worst case human fossil fuel emissions (RCP
8.5 scenario),
the accelerated rate of warming resulted in 25.5 percent permafrost
thaw.
Perhaps
more concerning was the fact that the study found that this 1.5 C
temperature threshold was reached by as early as 2023 under the worst
case fossil fuel burning scenario even as it was held off only to
2027 if rapid fossil fuel burning reductions were achieved. A broader
sampling of studies and natural variability hold out some hope that
1.5 C might be pushed back to the early to mid 2030s in the absolute
best case. However, considering the amount of human emissions already
released and in the pipeline even under the best cases, it appears
that crossing the 1.5 C threshold sometime in the near future is
unavoidable at this time (barring some unforeseen massive global
response and mobilization).
(Permafrost
losses under different human emissions scenarios through 2100 show
that continued fossil fuel burning results in between 47 and 87
percent loss of permafrost area by 2100 [RCP 4.5 and 8.5]. Image
source: Responses
and changes in the permafrost and snow water equivalent in the
Northern Hemisphere under a scenario of 1.5 C warming.)
Overall,
the study found that surface permafrost losses lagged the crossing of
the 1.5 C threshold by only about 10 years. And that the lowest
emissions scenarios (RCP 2.6) resulted in a leveling off of
permafrost losses to 24 percent by 2100. Meanwhile, the worst case
human greenhouse gas emissions scenarios (RCP 8.5) resulted in 87
percent permafrost area reductions by 2100.
Risk
of Serious Carbon Feedback Far Worse With Fossil Fuel Burning
With
so much carbon locked away in permafrost, heightened rates of thaw
present a risk that longer term warming might eventually run away as
millions and billions of tons of carbon are ultimately liberated.
Under moderate to worst case human fossil fuel burning scenarios, it
is estimated that permafrost carbon emissions could approach 1
billion tons per year or more.
At about 10 percent or more of the present human emission, such a
rate of release to the atmosphere is about equivalent to that
achieved during the
last hyper-thermal event of 55 million years ago (the
PETM). Moreover, a heightened response by large methane stores could
result in a more immediate warming effect as methane is 28
to 36 times more potent a heat trapping gas than carbon dioxide over
Century time scales.
A
risk of serious carbon feedbacks that accelerate rates of warming
this Century and over the longer term is not inconsiderable even with
a 24 percent loss of Permafrost under the best case scenario
identified by this study. However, the likelihood of a much more
serious feedback under continued fossil fuel burning is far more
apparent.
(UPDATED)
Links:
Hat
tip to Spike
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