Song of Flood and Fire Refrain: Epic Canadian Floods Wreck 5.5 Million Acres of Cropland

For the Northwest Territory of Canada, the story this summer has been one of record-setting wildfires. Fires casting away smoke plumes the size of thunderstorms, fires that burn regions of tundra the size of small states. Fires that just burn and burn and burn for weeks on end.

But to the south and east in Saskatchewan and Manitoba, the story is drastically different. For over the past month, unprecedented flooding in this region has wrecked untold damage to Canada’s farmlands.

Canada floods

(Powerful storms over Manitoba and Saskatchewan on July 23rd, 2014. Image source: LANCE-MODIS)

This situation is the result of an odd and wreckage-inducing tangle in the Jet Stream. For hot air has been funneling up over the Northwest Territory for the better part of two months now, pushing temperatures in this Arctic region into an unprecedented range topping the 70s, 80s, and even 90s on some days. This high amplitude ridge in the Jet Stream has been reinforced and locked in place, a result some scientists attribute to the loss of Arctic sea ice during recent years, setting up a hot weather pattern favorable to wildfires.

As the massive Arctic wildfires ignited and burned, they cast off giant streams of smoke, burdening the down-wind atmosphere with aerosol particles — an abundance of condensation nuclei for cloud formation. These smoke streams fell into a trough flowing down over Manitoba and Saskatchewan. The deep trough, often extending far into the Central US formed a kind of trap for storms and, like the fixed ridge over the Northwest Territory, it has remained in place for months on end.

Given this mangled positioning of atmospheric heat and moisture flows, it was only a matter of time before massive rainstorms erupted in the wake of the large-scale Canadian fires. And the result was an unprecedented flooding. The offspring of an unprecedentedly powerful and persistent atmospheric pattern set off by human warming.

Major Floods Wreck Canadian Crops

For some local farmers, the past couple of days have seen 48 hour rain totals in excess of 10 inches. A 100 year rain event at a scale few farmers in the region have ever seen. And the recent floods are just the latest in a series of heavy rainfalls that have been ongoing ever since early July. Flood follows flood follows flood. A progression that has left most farms swimming in inches to feet of water and mud.

In total, farmland encompassing 3 million acres in Saskatchewan and 2.5 million acres in Manitoba are now under water and are unlikely to produce any crops this year. As a result, wheat plantings are expected to decline by 9.8 percent from last year, canola is expected to decline by 5.8 percent from the June forecast, and oat is expected to decline by 6 percent, according to estimates from Bloomberg.

July flooding in these regions has so far resulted in over 1 billion dollars in damages to farmers. As much as half of these losses may not be covered as insurers are still reeling from severe moisture damages during 2011, just two years ago. As a result of the ongoing parade of storm casualties, insurers have also raised deductibles, leaving farmers more vulnerable to the odd and powerful new weather coming down the pipe.

The Part Played By Climate Change and a Mangled Jet Stream

We often hear of the expanding droughts of human-caused climate change wrecking croplands. But the upshot of expanding drought in one region is record downpours in another. And downpours, if they are intense enough, can have a negative impact on crops as well.

The cause of this is as simple as warming’s enhanced ability to evaporate water. For it is estimated by climate scientists that each degree C in temperature increase amplifies the global hydrological cycle by 7-8 percent. That means that current warming of about 0.8 C since the 1880s has resulted in about a 6% increase in both evaporation and precipitation. At the level of weather, this translates into more intense droughts under dry, hot weather, and more intense rainfall events under wetter, cooler weather.

High Amplitude Rossy Wave Over North America July 2014

(High amplitude Jet Stream wave pattern fueling wildfires in the Northwest Territory and record floods in Manitoba and Saskatchewan. Note the extreme northward projection of the Jet over the Northwest Territory and the strong, deep, trough back-flowing from Hudson Bay into Manitoba, Saskatchewan and the northern tier of the Central US. Image source: University of Maine.)

One mechanism that has tended to amplify drought and rain events during recent years has been a weakening and intensifying waviness of the Northern Hemisphere Jet Stream. This weakening has been attributed by some scientists to a large-scale recession of Arctic snow cover and sea ice. For since 2007, not one day has seen an average sea ice extent and the range has typically fallen into a zone between 20-50 percent below levels seen during the 1970s and 1980s. New major record low years in 2007 and 2012 have also fueled speculation that sea ice may completely melt away during one summer between now and 2030, 2025, or even 2020 — 50-100 years ahead of model predictions.

As the sea ice serves as a haven for cold air masses, its loss is bound to impact the resiliency of these systems and since a solid pool of cold air to the north is a major driver of Northern Hemisphere upper air currents, the weakening of this cold pool has had dramatic impacts on climates.

Dipole hot-cold pattern associated with mangled jet stream

(Extreme dipole hot/cold pattern associated with Jet Stream mangled by climate change. Image is for July 14, a match to the above Jet Stream shot. Note the extreme heat in the ridge and the much cooler air in the trough. This is exactly the kind of pattern we would associate with sea ice retreat and Jet Stream weakening. Image source: University of Maine)

For this year, the ridge over Canada’s Northwest territory was a direct upshot in a northward retreat of the Jet Stream over Canada and, at times, into the Arctic Ocean. This set the stage for severe wildfires in the zone of warmth underneath this ridge pattern. To the east, a powerful downsloping trough pulled cooler air into Saskatchewan and Manitoba as well as over the Central and Eastern US. This set the pattern up for cooler than average conditions as well as for strong rainstorms.

The crop-shattering events of July were a direct result of this climate change induced ‘Song of Flood and Fire.’ A pattern we’ve seen repeat again and again over the past few years and one that may well intensify as both time and human-caused warming advance.

Links:

Canada’s Record Rains Cut Wheat Averages to Three Year Low

Is Global Warming Causing Extreme Weather via Jet Stream Waves?

Top Climate Scientists Explain How Global Warming Amps Up the Hydrological Cycle, Wrecks the Jet Stream to Cause Dangerous Weather

LANCE-MODIS

University of Maine

A Song of Flood and Fire

Hat-tip to Colorado Bob

 

 

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Far Worse than Being Beaten with a Hockey Stick: Michael Mann, Our Terrifying Greenhouse Gas Overburden and Heating the Earth by + 2 C by 2036

I’m going to say something that will probably seem completely outrageous. But I want you to think about it, because it’s true.

You, where-ever you are now, are living through the first stages of a disaster in which there is nowhere to run, nowhere to hide, and no safe place on Earth for you to go to avoid it. The disaster you are now living through is a greenhouse emergency and with each ounce of CO2, methane and other greenhouse gasses you, I, or the rest of us, pump into the air, that emergency grows in the vast potential of damage and harm that it will inflict over the coming years, decades and centuries. The emergency is now unavoidable and the only thing we can hope to do through rational action is to reduce the degree of harm both short and long term, to rapidly stop making the problem worse, and to put human ingenuity toward solving the problem rather than continuing to intensify it.

But damage, severe, deadly and terrifying is unleashed, in effect and already happening, with more on the way.

*    *    *    *    *

Manns-hockey-stick

(Michael Mann’s famous Hockey Stick graph showing Northern Hemisphere temperatures over the past 1,000 years. The influences of human warming become readily apparent from the late 19th to early 21rst centuries. But human greenhouse gas forcing has much greater degrees of warming in store.)

This week, Michael Mann wrote an excellent piece describing the immediacy of our current emergency in the Scientific American. In typical, just the facts, fashion, he laid out a series of truths relevant to the current greenhouse catastrophe. These facts were told in a plain manner and, yet, in a way that laid out the problem but didn’t even begin to open the book on what that problem meant in broader context.

Michael Mann is an amazing scientist who has his hand on the pulse of human-caused climate change. He is a kind of modern Galileo of climate science in that he has born the brunt of some of the most severe and asinine attacks for simply telling the truth and for revealing the nature of our world as it stands. But though Mann’s facts are both brutal and hard-hitting for those of us who constantly read the climate science, who wade through the literature and analyze each new report. By simply stating the facts and not telling us what they mean he is hitting us with a somewhat nerfed version of his ground-breaking Hockey Stick. A pounding that may seem brutal when compared to the comfortable nonsense put out by climate change deniers and fossil fuel apologists but one that is still not yet a full revelation.

I will caveat what is a passionate interjection by simply saying that Michael Mann is one of my most beloved heroes. And so I will do my best to help him out by attempting to lend more potency to his already powerful message.

2 C by 2036 — Digging through the Ugly Guts of it

All that said, Michael Mann laid out some brutal, brutal facts in his Scientific American piece. Ones, that if you only take a few moments to think about are simply terrifying. For the simple truth is that the world has only a very, very slim hope of preventing a rapid warming to at least 2 C above 1880s levels in the near future and almost zero hope altogether of stopping such warming in the longer term.

The first set of figures Mann provides involves the current greenhouse gas forcing. Current CO2 levels are now at the very dangerous 400 parts per million threshold. Long term, and all by itself, this forcing is enough to raise global temperatures by between 2 and 3 degrees Celsius. But hold that thought you were just about to have, because we haven’t yet included all the other greenhouse gasses in that forcing.

Mann, in the supplemental material to his Scientific American paper, notes that the total forcing of all other greenhouse gasses currently in the atmosphere is about 20% of the total CO2 forcing. This gives us a total CO2 equivalent forcing of 480 ppm CO2e, which uncannily mirrors my own analysis here (the science may have under-counted a bit on the methane forcing, but this value is likely quite close to current reality for both the short and long term).

480 ppm CO2e is one hell of a forcing. It is nearly a 75% greater forcing than 1880s values and, all by itself, is enough to raise temperatures long-term by between 3.5 and 4.5 degrees Celsius.

And it is at this point that it becomes worthwhile talking a bit about different climate sensitivity measures. The measure I am using to determine this number is what is called the Earth Systems Sensitivity measure (ESS). It is the measure that describes long term warming once all the so called slow feedbacks like ice sheet response (think the giant glaciers of Greenland and West Antarctica) and environmental carbon release (think methane release from thawing tundra and sea bed clathrates) come into the equation. Mann, uses a shorter term estimate called Equilibrium Climate Sensitivity (ECS). It’s a measure that tracks the fast warming response time once the fast feedbacks such as water vapor response and sea ice response are taken into account. ECS warming, therefore, is about half of ESS warming. But the catch is that ECS hits you much sooner.

At 480 ppm CO2e, we can expect between 1.75 and 2.25 degrees C of warming from ECS. In essence, we’ve locked about 2 C worth of short term warming in now. And this is kind of a big deal. I’d call it a BFD, but that would be swearing. And if there is ever an occasion for swearing then it would be now. So deal with it.

Mann, in his article, takes note of the immediacy of the problem by simply stating that we hit 2 C of shorter term ECS warming once we hit 405 ppm CO2 (485 CO2e), in about two to three years. And it’s important for us to know that this is the kind of heat forcing that is now hanging over our heads. That there’s enough greenhouse gas loading in the atmosphere to push warming 2 C higher almost immediately and 4 C higher long term. And that, all by itself, is a disaster unlike anything humans have ever encountered.

Global Fossil Fuel Emission

(Global annual fossil fuel emission is currently tracking faster than the worst-case IPCC scenario. Aerosols mask some of the heating effect of this enormous emission, what James Hansen calls ‘a Faustian Bargain.’ Image source: Hansen Paper.)

But there is a wrinkle to this equation. One that Dr. James Hansen likes to call the Faustian Bargain. And that wrinkle involves human produced aerosols. For by burning coal, humans pump fine particles into the atmosphere that reflect sunlight thereby masking the total effect of the greenhouse gasses we have already put into the atmosphere. The nasty little trick here is that if you stop burning coal, the aerosols fall out in only a few years and you then end up with the full heat forcing. Even worse, continuing to burn coal produces prodigious volumes of CO2 while mining coal pumps volatile methane into the atmosphere. It’s like taking a kind of poison that will eventually kill you but makes you feel better as you’re taking it. Kind of like the greenhouse gas version of heroin.

So the ghg heroin/coal has injected particles into the air that mask the total warming. And as a result we end up with a delayed effect with an extraordinarily severe hit at the end when we finally stop burning coal. Never stop burning coal and you end up reaching the same place eventually anyway. So it’s a rigged game that you either lose now or you lose in a far worse way later.

Mann wraps coal and other human aerosol emissions into his equation and, under business as usual, finds that we hit 2 C of ECS warming by 2036 as global CO2 levels approach 450 ppmv and global CO2e values approach 540 ppmv. At that point, were the aerosols to fall out we end up with an actual short term warming (ECS) response of 2.5 to 3 C and a long term response (ESS) of about 5 to 6 C. (Don’t believe me? Plug in the numbers for yourself in Mann’s climate model here.)

So ripping the bandaid off and looking at the nasty thing underneath, we find that even my earlier estimates were probably a bit too conservative and Mann, though we didn’t quite realize it at first, is hitting us very hard with his hockey stick.

What does a World That Warms So Rapidly to 2 C Look Like?

OK. That was rough. But what I am about to do is much worse. I’m going to take a look at actual effects of what, to this point, has simply been a clinical analysis of the numbers. I’m going to do my best to answer the question — what does a world rapidly warming by 2 C over the next 22 years look like?

Ugly. Even more ugly than the numbers, in fact.

First, let’s take a look at rates of evaporation and precipitation. We know that, based on past research, the hydrological cycle increases by about 6% for each degree Celsius of temperature increase. So far, with about .8 C worth of warming, we’ve had about a 5% increase in the hydrological cycle. What this means is that evaporation rates increase by 5% and precipitation events, on average, increase by about 5%. But because weather is uneven, what this does is radically increase the frequency and amplitude of extreme weather. Droughts are more frequent and more severe. Deluges are more frequent and more severe.

(Program in which top climate scientists explain how global warming increases the intensity of evaporation and precipitation all while causing dangerous changes to the Jet Stream.)

At 2 C warming we can change this loading from a 5% increase in the hydrological cycle of evaporation and precipitation to a 12% increase. You think the droughts and deluges are bad now? Just imagine what would happen if the driver of that intensity more than doubled. What do you end up with then?

Now let’s look at something that is directly related to extreme weather — sea ice loss. In the current world, about .8 C worth of warming has resulted in about 3.2 C worth of warming in the polar regions. And this warming has resulted in a massive and visible decline of sea ice in which end summer volume values are up to 80% less than those seen during the late 1970s. This loss of sea ice has had severe effects on the Northern Hemisphere Jet Stream, both pulling it more toward the pole and resulting in high amplitude Jet Stream waves and local severe intensification of storm tracks. At 2 C worth of global warming, the Arctic heats up by around 7 C and the result is extended periods of ice free conditions during the summer and fall that last for weeks and months.

stroeve-barret-p-10-plus-2012

(Actual rate of sea ice loss vs IPCC model predictions. The most recent record low value achieved in 2012 is indicated by the dot. Image source: Assessment of Arctic Sea Ice/UCAR Report.)

The impacts to the Northern Hemisphere Jet Stream are ever more severe as are the impacts to Greenland ice sheet melt. Under such a situation we rapidly get into a weather scenario where screaming temperature differentials between the North Atlantic near Greenland and the warming tropics generate storms the likes of which we have never seen. Add in a 12% boost to the hydrological cycle and we get the potential for what Dr. James Hansen describes as “frontal storms the size of continents with the intensity of hurricanes.”

Greenland melt itself is much faster under 2 C of added heat and the ice sheets are in dangerous and rapid destabilization. It’s possible that the kick will be enough to double, triple, quadruple or more the current pace of sea level rise. Half foot or more per decade sea level rise rapidly becomes possible.

All this severe weather, the intense rain, the powerful wind storms and the intense droughts aren’t kind to crops. IPCC projects a 2% net loss in crop yields each decade going forward. But this is likely to be the lower bound of a more realistic 2-10 percent figure. Modern agriculture is hit very, very hard in the context of a rapidly changing climate, increasing rates of moisture loss from soil and moisture delivery through brief and epically intense storms.

The rapid jump to 2 C is also enough to put at risk a growing list of horrors including rapid ocean stratification and anoxia (essentially initiating a mass die off in the oceans), large methane and additional CO2 release from carbon stores in the Arctic, and the unlocking of dangerous ancient microbes from thawing ice, microbes for which current plants and animals do not have adequate immune defenses.

How do we avoid this?

In short, it might not be possible to avoid some or even all of these effects. But we may as well try. And this is what trying would look like.

First, we would rapidly reduce human greenhouse gas emissions to near zero. As this happens, we would probably want a global fleet of aircraft that spray sulfate particles into the lower atmosphere to make up for the loss of aerosols once produced by coal plants. Finally, we would need an array of atmospheric carbon capture techniques including forest growth and cutting, then sequestration of the carbon stored by wood in lakes or in underground repositories, chemical atmospheric carbon capture, and carbon capture of biomass emissions.

For safety, we would need to eventually reduce CO2 to less than 350 ppm, methane to less than 1,000 ppb, and eliminate emissions from other greenhouse gasses. A very tall order that would require the sharing of resources, heroic sacrifices by every human being on this Earth, and a global coordination and cooperation of nations not yet before seen. Something that is possible in theory but has not yet been witnessed in practice. A test to see if humankind is mature enough to ensure its own survival and the continuation of life and diversity on the only world we know. A tall order, indeed, but one we must at least attempt.

Links:

Earth Will Cross Climate Danger Threshold by 2036

What does a World at 400 Parts per Million CO2 Look Like Long-Term?

One Scientist Argues 2036 Could be Point of No Return for Climate Disaster

A Faustian Bargain on the Short Road to Hell

Doubling Down on our Faustian Bargain

Dr. Jennifer Francis, Top Climate Scientists Explain How Global Warming Aps the Hydrological Cycle and Wrecks the Jet Stream to Unleash Extreme Weather

Assessment of Arctic Sea Ice/UCAR Report

 

Triggers to Release the Methane Monster: Sea Ice Retreat, Ocean Warming and Anoxia, Fires, Sea Level Rise and The Fresh Water Wedge

Perhaps the most hotly debated topic among climate scientists, when they are not facing off with the ignorance of underhanded climate change deniers, is the potential rate of Earth Systems response to human caused climate change. In general, the low hanging fruit of climate research is a more easy to puzzle out pace of likely warming due to the direct forcing of human greenhouse gas and CO2 emissions and the more rapid climate feedback coming from increasing water vapor due to increased evaporation. But higher up the tree hang the critical fruits of pace of albedo change and pace of carbon response as the Earth System warms. Understanding these two will provide a much greater clarity to the question of a long term rate of warming given a doubling of atmospheric CO2.

Paleoclimate, Paleoclimate, and Paleoclimate

Perhaps the best way to test the accuracy of our long-term Earth Systems global warming and climate models is to use temperature proxy data from past ages in Earth’s history. And, based on these proxy measures, we find that the long term warming from each doubling of CO2 is at least 6 degrees Celsius. Though the proxies are not perfect, they are in general agreement on a range of potentials averaging near this figure. And these measurements can provide some confidence that the total long-term warming from a doubling of CO2 is at least twice that caused by a CO2 increase and the related water vapor rise alone.

More accurate measures closer to the current day are even less reassuring. Looking at the ice-age and interglacial transitions over the last 500,000 years, we find that a very small forcing provided by orbital changes, resulting in a global increase in solar insolation of about .5 Watts per meter squared combined with changes in the angle at which sunlight hits the Earth (Milankovitch Cycles), is enough to, over the long term, increase CO2 levels by 100 ppm (from 180 to about 280), increase methane levels by about 300 parts per billion (ppb) and (here’s the stunning kicker) raise world temperatures by a whopping 5 degrees Celsius globally and 13 degrees Celsius at the poles.

Changes in Temperature and Methane Concentration

Changes in Temperature and Methane Concentration

(Image source: NASA)

A Human Forcing Six Times Greater Than That Which Ended the Last Ice Age

It should be a serious concern to climate scientists that the initial forcing of just .5 Watts per meter squared resulted in a relatively moderate 100 ppm CO2 and 300 ppb methane response which then combined to force temperatures radically higher. By comparison, the current human emission of 120 ppm CO2 and 1100 ppb CH4 (methane) and rising, combine with other human greenhouse gasses such as Nitrous Oxide, Tropospheric Ozone (human emission), Clorofluorocarbons and Halons to provide an initial forcing of fully 3 Watts per meter squared or about 6 times the total forcing that resulted in the last ice age’s end and ultimately set in place feedbacks that pushed global temperatures 5 degrees hotter (Data source: Recent Greenhouse Gas Concentrations).

Earth’s Own Carbon Stocks are Vast

So why was so small an initial solar forcing enough to end an ice age and, ultimately warm the poles by 13 degrees (C) and the globe by 5 degrees C and what does this mean when the human forcing is now at least six times greater?

In short, the Earth holds vast stores of carbon in the form of CO2 in its oceans, organic carbon in its tundra and frozen beneath land ice, and in very large stores of methane hydrates on the sea bed. Any forcing that is large or occurs over a very long period of time will act continuously on these sources, pushing more and more of the carbon out until all of the stores newly exposed to that forcing are emitted, the feedback warming kicks in, Earth albedo changes as ice sheets respond (also a source of additional heat), and Earth gradually reaches a new energy equilibrium state.

In the current day, melting tundra (both land and ocean) in the Northern Hemisphere holds about 1,500 gigatons of carbon (NSIDC), the oceans contain between 2,000 and 14,000 gigatons of methane hydrate (USGS), and these same oceans hold about 1,000 gigatons of carbon (CO2) in solution near the surface and 38,000 gigatons of carbon near the sea floor (University of New Hampshire: Global Carbon Pools/Fluxes).

USGS Methane Hydrate

USGS Methane Hydrate

Melting tundra releases its carbon stores as CO2 in an aerobic/oxygen environment and as methane in an anaerobic and anoxic environment. Thawing methane hydrates release methane into the oceans of which some enters the atmosphere. And warming oceans eventually are unable to uptake a rising level of atmospheric CO2 and, in extreme cases, begin emitting CO2 back into the atmosphere.

When compared to the gentle, though long term, nudge to the Earth’s carbon stocks generated by orbital changes and a slight increase in solar insolation that ended the last ice age, the human forcing equates to a very great and rude shove. And if that much more gentle nudge was enough to liberate 100 ppm and 300 ppb of methane from the Earth system into the Earth’s atmosphere, then how much will the now much faster and harsher human forcing put at risk of liberation?

Methane Release Sources in the Arctic

That human greenhouse gas emissions are rapidly warming the Earth at a rate of about .2 degrees Celsius per decade and that carbon emissions from the Earth environment are likely to increasingly result from this rapid and rising rate of warming is a given. At issue is how fast and powerful an Earth systems response will be. And one critical issue in understanding the speed of this potential response is rate of methane release (CO2 release is another issue that will be explored in another blog).

Methane is a very powerful greenhouse gas. Over twenty years time, it estimated to produce about 105 times the forcing of a similar volume of CO2 (this value is estimated to be about 25 times a similar volume of CO2 over 100 years time). So large pulses of this gas could result in a doubling or more of the total greenhouse gas forcing already acting on the Earth system. Such catastrophic releases are hypothesized to have acted during other periods of rapid warming such as during the PETM and Permian hyperthermals.

The above, admittedly lengthy preamble, is needed to give context to this specific issue: potentially large methane releases as a result of Arctic warming and a number of related release mechanisms that may increasingly come into play. However, before we drill down to mechanisms, let’s look at the disposition of potential Arctic methane sources to give us a basis for our degree of concern.

Thawing Arctic Permafrost, as mentioned above, provides a source of 1,500 gigatons of carbon, some of which will be released as methane as it melts to liberate its carbon stores to surface, subterranean, and subsea environments. Some of this permafrost is land-based, some of it is submerged, as on the East Siberian Arctic shelf. As the permafrost thaws, decay and release of this carbon into the atmosphere is likely to gradually build, providing a growing pool of both methane and carbon emissions. That said, a climate change establishes a number of environmental mechanisms created that are likely to result in greater and greater volumes of this store being released over time. These mechanisms may push methane in a slow and gradual way. But, as we proceed down the dangerous path of rapid human-caused warming, there is increasing danger of large, sudden releases.

In addition, the same expanding set of environmental changes could result in a higher percentage of this vast store being emitted as methane.

Stable Sea Bed Clathrates represent an unknown portion that is likely a majority of the estimated 500-2,000 gigatons of methane hydrates in the Arctic environment. These clathrates compose methane locked in ice lattice structures that occur around 200 meters below the sea bed. Release of these clathrates requires a heat forcing to not only penetrate into the ocean waters, but for it to also reach the clathrates below hundreds of feet of rock and mud. Once the clathrates are disassociated, they must travel through cracks in the rocks and mud, and then through the water column to reach the ocean surface and the atmosphere. On the way, some of the liberated methane dissolves in sea water and another portion is taken in by methane eating organisms. If the pulse is strong enough, the ocean water saturated enough, and the methane eating organisms sparse enough, a greater portion of this released methane will reach the surface.

Ice Age Relics are clathrates that have formed as shallow as 20 meters beneath the sea floor. They are thought to have formed under the glacial cold that encased the Arctic over the last 2 million years and that occurred with particular intensity over the last 800,000 years. These ice age depositions are particularly vulnerable to more rapid release and their expansion during the last glacial period results in a set of carbon stocks that are very vulnerable to rapid emission. In this case, we find yet one more reason why a rapid rise out of a period of glaciation is a rather dangerous climate circumstance. The deposition of carbon stores are placed in regions more vulnerable to thaw and release once warming is underway.

In sum, these three represent a majority of potential methane release sources.

Rumors of Fire: The East Siberian Arctic Shelf Emission

(Please ignore the cheesy intro music and proceed on to the interview)

During the 1990s, researchers noticed a methane overburden in atmospheric regions around the Arctic Circle. This overburden was seen as an indication that large local methane emissions were occurring in the Arctic. Subsequent research found methane emissions from thawing Arctic tundra, from melt lakes and from peat bogs. In addition a large emission source was identified in the Arctic Ocean.

As of 2010, reports were coming in from the Arctic that the East Siberian Arctic Shelf was emitting more methane than the entire Earth ocean system combined. By 2011, an expedition to the Arctic found methane emission sources more than 1 kilometer across over the same region of submerged permafrost. By 2012, expeditions could no longer be conducted on the ice surface in the region of the East Siberian Arctic Shelf due to the fact that the sea ice there had become too thin and unstable to support research equipment.

Dr. Natalia Shakhova and Dr. Igor Similetov found that the permafrost cap over the shallow East Siberian Arctic Shelf seabed had become perforated. The cap locks a very large volume of methane, estimated to be about 500 gigatons, under constant cold and pressure. As the cap perforates, the cold and pressure release and increasing volumes of methane shoot up from the sea bed saturating the water with methane with some of the methane releasing to the surface.

Shakhova and Similetov warn that 1 percent or more of this methane could release over the course of decades as the sea ice continues to erode in the region of the East Siberian Arctic Shelf and the undersea permafrost continues to perforate. Just a 1 percent release would be enough to double the amount of methane in the Earth’s atmosphere, resulting in a .5 watt per meter squared forcing from an ESAS release alone. The researchers also identify the potential for a much larger, 50 gigaton release, which would more than double the current human GHG forcing over the course of just a few decades.

Such a large potential release was the subject of a much-debated Nature article by Peter Wadhams (read more here). And it was this article that raised the question of potential mechanisms that could result in such large releases of methane from the Arctic in the coming years.

The Arctic Under Heat: Ever More Powerful Mechanisms For Release

In examining potential release methane release mechanisms we will start with those currently acting on the East Siberian Arctic Shelf and work our way outward to the greater Arctic environment. It is worth noting that a paper by Carolyn Ruppel recently refuted Shakhova and Similetov’s findings, but that the Ruppel paper did not study the region of the East Siberian Arctic Shelf in question, only a related area of the Beaufort Sea which has not been found to currently show large, powerful, or widespread methane hydrate release.

East Siberian Sea

East Siberian Sea

(Image source: Commons)

Taking the Ice Lid off of a Shallow Sea. In the case of the East Siberian Arctic Shelf, rapidly warming air and ocean combine with rapidly retreating sea ice to create what seems to be a powerful and concerning release mechanism. The East Siberian Arctic Shelf is a 2 million square kilometer region that composes some of the Arctic’s densest carbon stores. It represents about 1/5 the Arctic Ocean area and is thought to contain about 500 gigatons of shallow sea bed methane hydrates. Over the past few decades, this region has warmed very rapidly, at the rate of about .5 degrees Celsius every ten years. This warming, at about 2.5 times the global rate, has resulted in a very rapid weakening and retreat of sea ice from the surface waters of a shallow sea that is, on average, about 50 meters deep. In recent years, summer sea ice has almost completely retreated from the ESAS, leaving a dark ocean surface to absorb sunlight and to rapidly warm. Measurements from the region show that water temperatures have increased by as much as 7 degrees Celsius above average once the sea ice pulls away. With the ice now gone, surface winds provide great mobility and mixing of the water column, this results in much of the surface water heating being transported down to the seabed. It also draws methane rich waters up from below where they can contact the air and release some of the water-stored methane.

Shakhova and Simeletov have observed perforations of the subsea permafrost releasing large volumes of methane from the East Siberian Arctic Shelf since 2008 and, as noted above, many of the hydrates stored beneath this permafrost cap are far shallower than is typical for a normal ocean seabed due to the fact that they are ice age relics. This combination of mechanisms provides the greatest current risk for rapid methane release. However, a number of other mechanisms are increasingly coming into play that may add to the, already concerning set of risks for rapid ESAS methane release.

Melting Tundra, Hot Lakes and Arctic Wildfires. NSIDC has identified about 1,500 gigatons of organic carbon locked in tundra systems throughout the Arctic. As the Arctic is forced to rapidly warm, larger and larger portions of this vast carbon store begin to thaw. Once the tundra melts, this carbon is subject to breakdown and action by microbes. This process of decay releases CO2 in dry environments and methane in wet, anoxic environments. Much of the tundra melt is subterranean. As such, this tundra melt is locked away in moist pockets that have little access to airflow. These pockets are at risk of being broken down into methane by anaerobic microbes. In some sections, tundra collapses and fills with water to form melt lakes. These lakes contact the anaerobic melt regions and create their own anaerobic bottom systems for carbon breakdown and release. Many of these lakes are so hot with methane that they provide emissions with high enough concentration to burn.

As the Arctic experiences more and more heatwaves, a far greater expanse of this extreme northern region is subject to wildfires. These fires are increasingly found to have burned deep into the soil. Reports from the Arctic find that fires have incinerated as many as 50% of the stumps of trees in a wildfire zone and consumed the carbon rich soil to a layer as deep as 3 feet below the surface. The action of wildfires further breaks open the soil and tundra cap providing passages to release any methane stored in anaerobic pockets beneath.

With these tundra regions composing so large a volume of carbon and with these areas being subject to increasingly rapid melting and increasingly energetic wildfires, larger and larger methane releases are entirely likely.

Ocean Warming, Anoxia, and the Fresh Water Wedge. As the years and decades progress and Arctic sea ice becomes more scarce, there is an increasing risk of large freshwater melt pulses from Greenland to combine with a warming Arctic Ocean to further amplify methane release. With the increasing removal of sea ice, Arctic Ocean temperatures surge, spreading a wider and wider area of heat forcing deeper and deeper into the water column and, eventually, into the seabed itself.

Some of this warming is visible in climate models projecting temperature and precipitation change throughout the Arctic over coming decades:

Projected temperature and precipitation change above the Arctic Circle.

Projected temperature and precipitation change above the Arctic Circle.

(Image source: Climate State)

A warmer Arctic Ocean is a less oxygen rich environment. The heat reduces the oxygen in solution, creating more anaerobic environments for organic carbon to break down as methane. Warmth also creates a greater sea-bed forcing for spontaneous and long-term release of methane hydrates.

As the seas surrounding Greenland warm and the Greenland environment takes in more of this latent heat, Greenland melt rates will continue to increase. The large fresh water pulses from Greenland will push the Gulf Stream further and further south, reducing the mixing of seawater in and near the Arctic, further reducing oxygen levels. These pulses will also act as a wedge, forcing warmer, saltier waters to dive down toward the ocean bottom as a fresh water cap expands from the Arctic Ocean southward (see Does Fresh Water Runoff Change Ocean Circulation to Unlock Deepwater Hydrates?). This mechanism will create a cool surface, hot depths ocean environment for the Arctic Ocean and northern latitude regions surrounding it.  Additional fresh water is likely to come from the continents as rates of precipitation increase, further adding to the fresh water cap and the creation of a growing region of stratified ocean with cooler, fresh water at the surface and a growing pool of warmer water below.

Unfortunately, large freshwater additions from melting snowcover and increasingly severe rainfall events, like the massive Yakutia floods have already resulted in changes to Arctic Ocean circulation, creating a large freshwater cap near the Beaufort and resulting in the risk of fresh water pulses entering the Pacific Ocean. A NASA animation shows how these changes are already ongoing:

And we have also noticed a great increase in ocean bottom heat content concentrated near the polar regions.

Thus we have three factors acting in concert to increase methane release. First, sea ice retreats to warm the Arctic Ocean. Second, increasing freshwater inflows divert the warmer waters toward the ocean bottom. Third, the warmer waters are less oxygen rich, creating more anoxic environments for anaerobic bacteria to break down organic carbon from thawing permafrost into methane. These anaerobes will receive plenty of nutrients from the waters washing off of glaciers and continents and will likely create great blooms over large areas as seas continue to warm. These combined forcing mechanisms will likely destabilize the weakest methane hydrate reserves first even as the anaerobes go to work on the newly liberated organic carbon.

Sea Level Rise Floods Large Regions of Tundra. A final mechanism for methane release is the rise of a less oxygenated Arctic Ocean to flood large sections of coastal tundra in Siberia, putting it under water and in an oxygen poor environment in which anaerobic bacteria can act to convert organic carbon into methane. A wide swath of coastal Siberia is low lying and, in some cases, is vulnerable to sea level rise for tens or even hundreds of kilometers inland. Over the years, larger sections of this region will be claimed by the sea, adding their carbon stores to an oxygen poor ocean bottom region.

Together, a rapidly destabilizing ESAS, a rapidly retreating ice sheet, increasing Arctic Ocean anoxia, increasing fresh water runoff into the Arctic Ocean, numerous anoxic environments within tundra thaw regions, increasingly energetic wildfires, expanding regions of stratified waters with hot ocean bottoms and cooler ocean surfaces, and seas rising to flood areas of thawing tundra provide sufficient and numerous mechanisms to be seriously concerned about Arctic methane release as an amplifier and potential multiplier to human caused warming.

Links:

Milankovitch Cycles

NASA: Changes in Methane Concentration

CDAIC: Recent Greenhouse Gas Concentrations

NSIDC: It’s All About Frozen Ground

USGS: Methane Hydrates

University of New Hampshire: Global Carbon Pools/Fluxes

Nature: The Vast Costs of Arctic Change

Does Fresh Water Runoff Change Ocean Circulation to Unlock Deepwater Hydrates?

A Looming Climate Shift: Will Ocean Heat Come Back to Haunt US?

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