(Image source: Methane Tracker)
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.
The geographic region of Yedoma and its related loess layers are indicated on the map below. Note the large off-shore region extending into the East Siberian Arctic Shelf:
(Image source: Ole Log)
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.
(Image source: NASA/Lance-Modis)
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