Yedoma
Region of Russia Showing Significant Methane Pulse
August
7 Methane Pulse, Yedoma
(Image
source: Methane
Tracker)
Robertscribbler,8 August, 2013
August 4-7 saw a large and growing pulse of methane emerging from the Yedoma region of Russia and the Siberian Arctic over the past week. By Wednesday, about 30 percent of the Yedoma region was covered in methane readings exceeding 1950 parts per billion, according to measurements published through the online resource — Methane Tracker.
This pulse emerged in conjuction with late summer fires and heatwaves scorching this massive region of permafrost above or near the Arctic Circle. Yedoma includes a broad expanse of permafrost ranging from Siberia to a shallow sea known as the East Siberian Arctic Shelf. In total, this region is estimated to hold 500 gigatons of carbon locked in, now thawing, tundra.
The
region has come under increased scrutiny and study during recent
years as temperatures throughout the Arctic and especially in this
area have rapidly risen due to human warming. While global
temperatures have increased by an average of around .2 degrees
Celsius per decade, temperatures in Yedoma have increased by more
than twice that rate at a whopping .5 degrees Celsius per decade. As
a result, most of the tundra, both land and shallow sea, is subjected
to increasing heat forcing and is at greater risk of releasing large
volumes of carbon into the atmosphere.
Originally,
it was estimated that Yedoma released about 4 megatons of carbon each
year. Instead, recent expeditions have found that the region releases
a staggering 44 megatons of CO2 and an estimated 4 megatons of
methane. The CO2 emission alone is greater than that pumped out by 1
million automobiles and, since methane is so powerful a greenhouse
gas, the forcing provided by the 4 megaton methane emission is nearly
twice that.
Recent
studies conducted by N. Shakhova have estimated that as much as 50
gigatons of the methane locked in the East Siberian Arctic Shelf
could rapidly destabilize and emit over a brief period of 1-50 years.
The Shakhova paper is refuted by another scientific paper produced by
C. Ruppel who claims that the global .2 degree Celsius temperature
increase each decade is not enough forcing for a rapid release. Peter
Wadhams, who produced a recent article for Nature, refutes these
findings noting that temperatures in the Arctic are warming faster
than the global average and that sea ice losses can result in very
strong, if briefer, temperature spikes during summer months that
provide a powerful forcing to the sub-sea methane. Wadhams
observations are refuted by other scientists — notably Gavin
Schmidt and David Archer, who favor a slow release scenario based on
what they have seen in various climate models.
In
context to this scientific argument is the well supported theory that
methane release contributed to rapid warming during past global
heating events such as the PETM and the Permian-Triassic.
Nevertheless,
we have seen a rising methane emission from the Arctic over the past
decade. These increases are not indicative of the extraordinarily
rapid release Shakhova has warned is possible. But they are still
rapid enough to raise local methane levels by a rate of 5-10 parts
per billion each year — nearly twice the global rate of increase.
What this rate shows is that Arctic methane emissions are occurring
at a faster pace and at relatively higher volumes than those in the
rest of the world.
The
Yedoma spike chronicled above by Methane Tracker is a troubling,
though not catastrophic, occurrence. It appears during a time when
high temperatures and wildfires are affecting a large region of
Yedoma where we see the methane pulse. It is possible that methane
seeping up through the tundra from anaerobic pockets where
methane-producing bacteria can thrive are venting into the atmosphere
as the tundra thaws. During times of high heat forcing, such as
periods of late summer at times when human warming has induced more
and more Arctic heatwaves, higher volumes of this methane are at risk
of venting into the atmosphere. In some places, the methane
concentrations are high enough to ignite in fires, as we have seen in
numerous melt ponds across the Arctic. In the presence of wildfires
driven by Arctic heatwaves, a high rate of methane emission creates a
volatile additive to an already anomalous situation.
Whether
or not catastrophic methane spikes of the kind Shakhova and Wadhams
warn of will result from human forcing, it is likely that methane and
related CO2 emissions will continue to increase throughout the Arctic
and at rates far faster than is correlated in the climate record over
the past 800,000 years. The carbon store there is vast, and the rate
of forcing increase is far faster than at any time in the geological
record. For reference, it took about 8,000 years for the Earth to
warm out of the last ice age. Temperature increases averaged at a
rate of .006 degrees Celsius per decade during this time. The current
rate of human-cased warming is more than 30 times that. Yet even with
this very slow level of forcing we find atmospheric CO2 and methane
levels rising significantly over the ice age to interglacial
transition period — with CO2 rising by 100 ppm and methane rising
by 300 ppb.
The
fact that even such slow forcings can result in such significant
responses should serve as a warning when we consider the current,
very rapid human temperature forcing. A related, more rapid, Earth
Systems methane feedback could quickly overwhelm sinks and provide a
much higher relative atmospheric methane level. Meanwhile, as we
consider this, very valid, concern, we observe significant and rising
methane emissions from the Arctic’s most vulnerable stores. Given
these two very valid concerns, it is both prudent and rational to
identify rising methane emissions as a current and growing threat.
***
Related:
Arctic Methane and Why Sea Ice Matters
http://www.youtube.com/watch?v=iSsPHytEnJM
Links:
No comments:
Post a Comment
Note: only a member of this blog may post a comment.