Methane Monster Finding Cracks in Earth’s Defenses: Is the Global Methane Sink Starting to Fade?

Annually, humans emit about 13.5 gigatons of carbon, or about 50 gigatons of CO2 equivalent gasses into the atmosphere. The measures are essentially the same — one just counts carbon weight, the other counts out all the additional hydrogen, oxygen, nitrogen or other atoms together with the carbon.

Of this massive volume, a volume at least six times the emission seen at any time in the geological past, even during the worst greenhouse gas extinction — the Permian — only a fraction remains in the atmosphere for any substantial period of time. This fraction continues to trap the heat and cause the effects we now see on a daily basis — extreme weather, record droughts, fires, floods, crop damage, sea ice loss, storms and an incessant rise in global temperatures.

The rest goes into what we call carbon sinks or stores.

Through the course of human-caused warming, scientists have been concerned that carbon sinks and stores will eventually fill up or, even worse, become emissions sources themselves. The result would be that a greater fraction of the human greenhouse gas emission would remain in the atmosphere longer and do even more damage through its now increased warming potential as natural sources began to emerge and multiply.

Atmospheric elevator

(Atmospheric elevator. Very large storms in the Pacific transport pollutants into the stratosphere. What impact is this having on one of the world’s major methane sinks — the hydroxyl shield? Image source: Alfred Wegener Institute.)

It is this kind of amplifying feedback that we’ve been sounding warnings on since 2012. And, according to new scientific research, there is serious reason for concern that another amplifying feedback in the form of erosion of the methane sink is now starting to develop coincidentally with rising rates of natural methane store emissions.

Methane — A Potent Heat Trapping Gas

And it is here in our chilling and cautionary tale that we come to the story of how methane acts to warm the atmosphere…

As a molecule, methane is an extraordinarily potent heat trapping gas. If CO2 were the tortoise — persisting for hundreds or thousands of years and gradually and inexorably building up a potent heating force, methane is the hare — providing a very intense burst of heating potential for a short period before being sucked out of the atmosphere by either the hydroxyl sink in the tropopause or through interaction with the soil.

The hydroxyl sink lives as a thin layer of a detergent-like molecule consisting of one oxygen atom and one hydrogen atom (HO). The layer exists along a boundary between the troposphere and the stratosphere called the tropopause. It forms when Nitrous Oxide (NO2) encounters Ozone (O3) and water vapor (H2O) at a height of about 8-10 miles where solar radiation is of a wavelength shorter than 315 nanometers. The radiation energy sets off a reaction between these three molecules producing a layer of hydroxyl, a reactive compound that breaks down all sorts of nasty chemicals floating around in our atmosphere. It also breaks down methane. A service that is quite valuable, especially when you consider that methane’s heat forcing, without the rapid oxidization powers of the hydroxyl layer, would be far, far greater.

The heat potential of a single methane molecule is 80 times that of a single CO2 molecule (in the presence of aerosols, it jumps to 105 times that of CO2, somewhat reducing the aerosol cooling effect). And so it’s probably a good thing that the lifespan of a methane molecule in the current atmosphere is only about 8 years. In contrast, CO2 lives about 500 years before weathering or the deep ocean finally knock it out.

As a fraction of total greenhouse gas forcing, scientists conservatively calculate that the total methane overburden represents about 60 parts per million of additional CO2 equivalent heat forcing or a little more than half the total additional heat forcing from CO2. But this calculation takes into account the notion that methane is short lived and will tend to drop out, resulting in relatively less methane heat forcing over time.

Earth’s Hydroxyl Shield Now Has a Gaping Hole

And so it is that today we encounter a bit of a problem. For it appears that a large hole has now been blown in the methane/hydroxyl sink over the Pacific Ocean.

Hydroxyl Hole

(A very large hole in the Earth’s protective Hydroxyl Layer discovered over the Western Pacific northeast of New Guinea during spring of 2014. Image source: Markus Rex, Alfred-Wegener-Institute.)

Though the cause of the current hole is unknown, what is known is that powerful thunderstorms in the region provide atmospheric lift and could have mixed in ozone destroying chemicals such as bromine and chlorine that significantly reduced one of the key constituents of hydroxyl formation.

The hole is quite large and while the initial paper by Markus Rex primarily noted concerns about additional volatile chemicals reaching the stratosphere through the hole, these major hydroxyl reductions over such a large area are also likely to lengthen the atmospheric lifespan of methane.

This feedback may well be a result of other human pollutants and have a possible negative effect on global warming by acting to significantly degrade a major carbon sink. If such an instance is confirmed, it may well be the first such case of its kind where two separate subsets of pollution create a kind of harmonic, but indirect, warming potential effect.

In any case, not a good outcome.

10 to 165% More Methane to be Released From Wetlands

A second very large methane sink/store is encompassed by the world’s vast swaths of wetlands. There, organic materials in the wetlands soil bind electrons needed by methane producing bacteria during regular wet-dry cycles, preventing a portion of the organic material from being broken down as methane. In essence, it’s a kind of indirect methane sink in that it prevents carbon-based materials from being converted to methane by already active methane producing bacteria.

But new research conducted by a team of Swiss and German researchers has found that as climate warms, wetlands are increasingly submerged, and large regions of tundra wetlands thaw, the electron binding process tends to run in reverse even as more wetlands become available for methane emission. In essence, warming both submerges more wetlands even as it generates more wetlands due to tundra thaw. It’s a kind of one, two punch that these researchers are saying could push global methane production radically higher.

As a result, the very large organic carbon store contained in wetlands would increasingly be emitted as methane and the wetlands would act less and less as a methane sink and more and more as a venting methane store. The new addition of wetlands from melting tundra only compounds the process. Researchers found that wetlands are likely to emit between 10 and 165% more methane due to these combined impacts.

It’s worth noting that global methane emissions from wetlands are currently about 165 teragrams (megatons metric) each year. So the new research estimates that annual emissions from these sources will increase by between 17 and 260 megatons annually. By comparison, the total annual methane emission from all sources (including the human addition) is about 600 megatons each year.

Pace of global atmospheric methane increases is tracked by NOAA’s Earth Systems Research Laboratory. Mauna Loa annual measures and trends can be seen here:

Global methane levels

(Global methane levels since 1983 as measured at the Mauna Loa Observatory. Image source: NOAA.)

Fading Sinks, Releases From Stores

These new discoveries — the formation of a hydroxyl shield hole and the recent study finding that global warming will lead to a greater annual release of methane from the world’s wetlands — are likely to combine with ongoing human methane emissions that are now radically increased due to hydrolic fracturing for new gas deposits and with potentially increasing methane emissions from subsea sources such as worldwide stores of methane hydrates and the very vulnerable methane stores in the East Siberian Arctic Shelf. The result is a much greater risk that current methane levels will rise and/or remain high for longer than expected. In total, it’s a significant risk of additional major warming on top of an already very powerful heat forcing coming from a rising human CO2 emission.


Markus Rex, Alfred-Wegener-Institute

Methane Climate Change Risk Suggested By Proof of Redox Cycling of Humic Substances

Sea Ice Melt, Methane Release Shows Amplifying Feedbacks to Human-Caused Climate Change


Global Methane Emissions From Oil and Gas

Methane Emissions From Wetlands

Hole Found in Natural Protective Layer

Tropospheric Chemistry

A Faustian Bargain on the Short Road to Hell

Hat Tip to Colorado Bob!


The Arctic Methane Monster’s Nasty Little Helpers: Study Finds Ancient, Methane Producing, Archaea Gorge on Tundra Melt

An emerging methane feedback in the Arctic. It’s something that, since last summer, I’ve been calling the Arctic Methane Monster. A beast of a thing composed of giant reserves of sea bed methane and an immense store of carbon locked away in Arctic tundra.

How dangerous and vicious the monster ends up being to a world set to rapidly warm by humans depends largely on three factors. First — how fast methane is released from warming stores in the sea bed. Second — how swiftly and to what degree the tundra carbon store is released as methane. Third — how large the stores of carbon and methane ultimately are.


(Thawing permafrost and organic carbon in Yedoma region of Russia. Image source: NASA.)

On the issue of the first and third questions, scientists are divided between those like Peter Wadhams, Natalia Shakhova and Igor Simeletov who believe that large methane pulses from a rapidly warming Arctic Ocean are now possible and warrant serious consideration and those like Gavin Schmidt and David Archer — both top scientists in their own right — who believe the model assessments showing a much slower release are at least some cause for comfort. Further complicating the issue is that estimates of sea-bed methane stores range widely with the East Siberian Arctic Shelf region alone asserted to contain anywhere between 250 and 1500 gigatons of methane (See Arctic Carbon Stores Assessment Here).

With such wide-ranging estimations and observations, it’s no wonder that a major scientific controversy has erupted over the issue of sea bed methane release. This back and forth comes in the foreground of observed large (but not catastrophic) sea-bed emissions and what appears to be a growing Arctic methane release. A controversy that, in itself, does little inspire confidence in a positive outcome.

But on the second point, an issue that some are now calling the compost bomb, most scientists are in agreement that the massive carbon store locked in the swiftly thawing tundra is a matter of serious and immediate concern.

Tundra Thaw by Human GHG Now Practically Inevitable

At issue here is the initial power of the human heat forcing and what consequences that forcing is likely to unlock. Consequences that are directly tied to the amount of greenhouse gasses we emit. A total forcing that is now likely equivalent to around 425 CO2e when taking into account the effect of human aerosols and an even more ominous 480 CO2e when and if those aerosols fall out (IPCC and MIT).

The first number, 425 CO2e, were it to remain stable over years, decades and centuries, is enough push global temperatures above the 1.5 C warming threshold that would thaw the northern hemisphere tundra. And within this tundra is locked a store of about 1,500 gigatons of carbon. A massive store that is set to eventually, thaw, decompose and release its carbon as either CO2 or methane over the long period of warmth that is to come.

Area of contiguous permafrost

(Northern Hemisphere Permafrost Zones. Image source: NASA.)

The immense size of this carbon store represents an extreme risk both for extending the period of human warming and for, potentially, generating a feedback in which natural warming adds to, rather than simply extends, human warming. By comparison, human fossil fuel emissions have already resulted in about 540 gigatons of carbon being released into the atmosphere. The tundra store alone represents nearly three times this amount. But the concern is not just the massive size of the tundra store now set to thaw, or the rate at which the tundra will, eventually, release its carbon to the atmosphere. The concern is also how much of the tundra store carbon is released as either methane or CO2.

Methane Provides a Strong Amplifying Feedback

Since methane’s radiative absorption is about 35 times that of CO2 by volume in the IPCC climate assessments (and its short term global warming potential is as much as 72 to 105 times that of a comparable amount of CO2) and since methane release sets off other feedbacks by turning into CO2 after it is oxidized and by increasing atmospheric water vapor, a strong greenhouse agent in its own right, a significant portion of tundra carbon being liberated as methane could result in a rather powerful heat amplification. In the worst case, such an amplification could set off conditions similar to those during which other mini-greenhouse gas runaways occurred — such as the Permian, Triassic and PETM events.

Which is why the release of a new paper should be cause for serious concern.

Ancient Archaea¬†— The Arctic Methane Monster’s Nasty Little Helpers

This week, a paper published in Nature Communications described findings based on a study of thawing Swedish permafrost. The study investigated how microbes responded to thawing tundra in various mires throughout warming sections of Sweden. What they discovered was the increased prevalence of an ancient methane producing micro-organism.

Billions of years ago, methane producing cyanobacteria or archaea were prevalent in the world’s oceans. The methane they produced helped keep the Earth warm at a time when solar output was much less than it is today. Later, as oxygen producing plants emerged, the archaea, to which oxygen was a poison, retreated into the anoxic corners of the more modern world. Today, they live in the dark, in the mud, or in the depths of oceans. There, they continue to eek out an existence by turning hydrogen and carbon dioxide into methane.

A kind of archaea, the newly discovered organism, named methanoflorens stordalenmirensis, was found to be exploding through sections of rapidly melting Swedish tundra. In fact, it is so at home in regions of melting permafrost that it blooms in the same way algae blooms in the ocean. As a result, it comes to dominate the microbial environment, representing 90% of the methanogens and crowding out many of the other microbes.

Distribution of Methanogen

(Methanogen shows global distribution. Each dot indicates a location where methanoflorens stordalenmirensis was discovered. Image source: Nature.)

That these massive archaea blooms can effectively convert large portions of the newly liberated tundra carbon store into methane was not at all lost on researchers:

“Methanoflorens stordalenmirensis seems to be a indicator species for melting permafrost. It is rarely found where there is permafrost, but where the peat is warmer and the permafrost is melting we can see that it just grows and grows. It is possible that we can use it to measure the health of mires and their permafrost. The recently documented global distribution also shows, on a much larger scale, that this microbe spreads to new permafrost areas in time with them thawing out. This is not good news for a stable climate“, said study author Rhiannon Mondav.

So what we have here is a billions year old microbe that thrives in wet regions called mires where permafrost is melting, rapidly converts tundra carbon to methane, readily spreads to new zones where permafrost melt occurs, and explodes into algae like blooms to dominate these environments.

One could not ask for a set of more diabolic little helpers for the already very disturbing Arctic Methane Monster…

Implications Going Forward: Arctic Methane Emission Not Currently Catastrophic, But Likely to Continue to Grow

Recent research shows that the current methane emission from all natural sources north of 53 degrees north latitude is on the order of 81 trillion grams (TG) each year. A portion of this, about 17 TG, comes from the East Siberian Arctic Shelf. Other inputs are from sea bed sources, thawing tundra and existing wetlands in the region. Meanwhile, the global emission, including both human and natural sources is in the range of about 600 TG each year. Overall, this emission is enough to overwhelm current sinks by about 40 TG each year, which results in continuing increases of atmospheric methane.

Atmospheric Methane Mauna Loa

(Atmospheric methane levels since 1969, Mauna Loa, show levels rising by about 200 ppb over the 45 year period. Image source: NOAA ESRL.)

As more and more of the tundra melts and as seabed methane continues to warm it is likely that total Arctic methane emissions will continue to rise, perhaps eventually rivaling or, in the worst case, exceeding the size of the human methane emission (350 TG). But, to do so, current Arctic and boreal emissions would have to more than quadruple — either through a slow increase (high likelihood) or through more catastrophic large pulse events (lower likelihood, but still enough for serious concern). By contrast, recent warm years have shown increases in the rate of methane flux/emission of around 5% with the average flux increase being around 2%.

It is worth noting that NOAA and a number of other agencies do track methane emissions in the Arctic but that a comprehensive tool set for accurately tracking the total emission does not appear to be currently available. Instead, various studies are conducted in an effort to capture total emissions levels. Monitoring does, however, track total atmospheric values.


Discovery of a Novel Methanogen Prevalent in Thawing Permafrost

Methane Producing Microbe Blooms in Permafrost Thaw

The Arctic Methane Monster

The Arctic Methane Monster Stirs

Living in a World at 480 CO2e

Caves Point to Thawing in Siberia

NSIDC: Climate and Frozen Ground

Thawing Permafrost Could Cause 2.5 Times the Warming of Deforestation

Is a Sleeping Giant Waking in the Arctic?

Radiative Forcing of Non CO2 Greenhouse Gasses

Carbon Tracker CH4

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