Climate news: Arctic seafloor methane release is double previous estimates, and why that matters

One of the greenhouse gases (GHGs) that Obama’s EPA Clean Power Plan doesn’t count is methane from leaks, for example, fracking leaks, fuel line leaks, transportation leaks, and so on. Yet methane (CH4) is one of the most powerful greenhouse gases known, though very short-lived (most atmospheric methane disappears in about 12 years, becoming CO2 and water vapor).

And one of the cornerstones of the idea that mankind still has a “carbon budget” — that we can still release even more CO2 and other greenhouse gases like methane, though a “limited” amount — is the idea that we can do a good job of modeling climate-changing feedbacks. We can do a good job of modeling some feedbacks, but we’re very bad at modeling others, and some feedbacks have so much randomness about them that modeling them becomes next to impossible.

For an example of seemingly good models that have gotten things drastically wrong, take a look at what 13 Arctic-ice models said about the ice melt rate (loss of ice is a feedback, since it’s cause by warming, and then feeds more warming back to the system):

Loss of summer Arctic sea ice (from the Copenhagen Consensus)

Loss of summer Arctic sea ice, modeled vs. observed (source here; adapted from Fig. 1 here)

 

All of the fuzzy lines are predictions of various models using the assumptions of that model. The heavy black line is the mean of those models. The red line is observed loss. Note that today, we’re about at the place the IPCC models had us reaching 90 years from now. The observations peak at about 9 million square kilometers, and we’re now at about 3 million. When we reach 1 million square kilometers, the Arctic will be considered “ice free.” Not long after that, summer ice will go to actual zero. With increased warming, winter ice will go to zero also.

See why I’m always saying we’re “wrong to the slow side”? If you think a climate event will happen in some number of years, cut it in half, at least, and maybe in half again.

For an example of a process that’s almost impossible to model, consider the disappearance of Antarctic ice shelves. They don’t go gradually; they hang around, then go suddenly and in big chunks, as they have recently. We’ve crossed the point of no return on large parts of the Western Antarctic shelf. No one saw that coming when it did, and there was no way to model it. That system is just too complex, with too many unknowns.

Frozen methane is one of the largest unknowns in climate prediction

Which brings us back to methane — in particular, frozen methane. By most accounts, there’s more than 1,000 GtC — a thousand billion (“giga”) tons of carbon — locked into the tundra and the peat bogs, and frozen at the bottom of the ocean in the Arctic region. As noted, methane is a short-lived but powerful GHG. “Greenhouse warming potential” (GWP) is a comparison of the warming effect of a substance relative to CO2 (which is assigned a GWP of 1). Here’s what methane’s GWP looks like over time:

How methane compares to CO2 as a warming agent over time. Blue line — IPCC from 2007.

How atmospheric methane compares to CO2 as a warming agent over time. Blue line source: IPCC, 2007.

The small dot at 20 years on the blue line says that in the first 20 years, atmospheric methane has 72 times the warming effect as CO2. The IPCC wrote that in 2007 in the report called AR4. Assessment Report 5 (AR5), out last year, increased that number from 72 to about 85. The IPCC has moved that number up in every report since 1995.

Now note the blue line to the left of that dot, in the less-than-20-year part of the chart, as it climbs toward 100. In the first five years, the effect of methane is over 100 times that of CO2, and again, that was the number as calculated in 2007. It’s larger by more recent calculations.

I said at the start of this piece that there’s more than 1,000 GtC in methane form — remember, methane contains the carbon molecule — stored in the Arctic. That’s conservative; the number is much higher.

(A note about units used to measure carbon: You’ll see Pg, petagrams, sometimes used as a unit of weight, for example, at the previous link. A “petagram” (Pg) has the same weight exactly as a “gigaton” (Gt). I’m going to translate everything to tons of carbon (tC) for this piece, no matter where the original measurement appears.)

Whatever the number, the methane’s been down there for millions of years, and if it stays down there, we’re in good shape. (Just like coal — most of it was formed several hundreds of millions of years ago, and until recently, it just sat under the earth doing no harm at all. The steam engine changed all that, got us to dig it back up and put it back in the air.)

The key questions about methane are — how fast is it leaking back into the atmosphere, and will that rate be stable? The answer to the first question is, by many accounts, not fast. In 2007, methane release from the vast, shallow East Siberian Arctic Shelf (ESAS) — one of several sources of methane — was put at 0.5 MtC per year. That’s half a megaton (a half-million tons) of carbon. Compare that to today’s rate of carbon emissions in CO2 form — 10 GtC per year.

A gigaton is 1,000 megatons, so quite a difference in scale. Methane may be 100 times more potent than CO2 as a GHG in its first few years (before it decays). But by weight, CH4 emissions are measured in the millions of tons of carbon, not the billions of tons. (Yet note that low number of 0.5 MtC for East Siberian releases — it’s been revised considerably upward. Read on.)

Will things stay like this, with methane emissions at a crawl? In a runaway warming scenario, there is certainly a point where all that methane will go into the air. Are we near that point? No one knows, though the consensus is that we’re not — at least not yet.

Arctic methane is leaking twice as fast as previously thought

Which brings us to the news and back to the uncertainties. That consensus I just mentioned — that we’re not near a “runaway methane” scenario — hides a sharp divide in the scientific community. There is a small group of researchers who think we could be near a methane tipping point.

In that group is the Russian research team of Natalia Shakhova and her husband Igor Semiletov, researchers at the University of Alaska Fairbanks (UAF) International Arctic Research Center. Here’s what they found recently (my emphasis):

Arctic seafloor methane releases double previous estimates

The seafloor off the coast of Northern Siberia is releasing more than twice the amount of methane as previously estimated, according to new research results published in the Nov. 24 [2013] edition of the journal Nature Geoscience.

The East Siberian Arctic Shelf is venting at least 17 teragrams of the methane [17 Mt or million tons] into the atmosphere each year. A teragram is equal to 1 million tons.

“It is now on par with the methane being released from the arctic tundra, which is considered to be one of the major sources of methane in the Northern Hemisphere,” said Natalia Shakhova, one of the paper’s lead authors and a scientist at the University of Alaska Fairbanks. “Increased methane releases in this area are a possible new climate-change-driven factor that will strengthen over time.”

… On land, methane is released when previously frozen organic material decomposes. In the seabed, methane can be stored as a pre-formed gas or as methane hydrates. As long as the subsea permafrost remains frozen, it forms a cap, effectively trapping the methane beneath. However, as the permafrost thaws, it develops holes, which allow the methane to escape. These releases can be larger and more abrupt than those that result from decomposition.

The findings are the latest in an ongoing international research project led by Shakhova and Igor Semiletov, both researchers at the UAF International Arctic Research Center. Their twice-yearly arctic expeditions have revealed that the subsea permafrost in the area has thawed much more extensively than previously thought, in part due to warming water near the bottom of the ocean. The warming has created conditions that allow the subsea methane to escape in much greater amounts than their earlier models estimated. Frequent storms in the area hasten its release into the atmosphere, much in the same way stirring a soda releases the carbonation more quickly.

Yes, I too caught the point about earlier models being wrong in the last paragraph above. Shades of Arctic sea ice models? I guess only time will tell.

But 17 megatons of methane is a sharp upward estimate from the 0.5 megatons just seven years earlier. Has methane emission changed, or is the measurement more precise?

Probably both. To a large degree emissions have changed, since Shakhova and Semiletov have been taking measurements by expedition for quite some time. In fact, I wrote about one of their previous discoveries — that they found kilometer-wide plumes of methane rising through the Arctic ocean — two years ago (my emphasis):

“Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we’ve found continuous, powerful and impressive seeping structures more than 1,000 metres [one kilometer] in diameter. It’s amazing,” Dr Semiletov said.

“I was most impressed by the sheer scale and the high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them,” he said.

A kilometer is over half a mile. Imagine how tall a half-mile wide undersea plume of methane gas is. The researchers found over 100 in a relatively small area and have extrapolated to thousands. 

The data isn’t in on the risk from methane

I want to close with these two points.

1. I mentioned at the start of this piece that some models were right, some very wrong, and some nearly impossible to construct. The behavior of the sequestered (captured, stored) methane, especially in the north latitudes, is in the third group — it’s very hard to model and extrapolate from. Many scientists, including many I respect, who have been in the forefront of the “zero carbon” bandwagon, don’t see an immediate danger from Arctic methane.

Eventually, yes, but immediately, no. If we let the system run out of control — by not reigning in the men and women determined to profit from carbon — we’ll cook the joint. But if we do stop the warming, stop the emissions we ourselves are causing, and do it fast enough, there’s a large contingent of scientists who say, we’ll probably avoid a massive methane release, for all sorts of reasons that, if listed, would make you think you’re back in chemistry class.

But science keeps finding things; that’s its beauty. As we learn more about methane and how it acts, and as we measure its emissions in the field, we could all get a surprise, like the Arctic ice surprise in the first chart above. That surprise has catastrophe written all over it.

2. The mythical “carbon budget” that supposedly allows us to emit an IPCC-blessed “limited” amount more of the various GHGs and still “stay safe,” that budget depends in part on the absence of a methane emissions feedback loop.

The IPCC calculates that, to have a ⅔ (66%) chance of staying below a “safe” 2°C of warming since pre-industrial times, we can emit no more than about 250 GtC (per their recent AR5). There are a lot of questionable assumptions built into that “budget”:

▪ That a ⅔ chance of not-death is a good enough chance.
▪ That “2°C warming is safe” isn’t just a guess that got frozen into wisdom.
▪ That Exxon, the Saudis and the Kochs somehow deserve any of the loot they have yet to monetize from carbon.

I’ll deal with each of those assumptions later, in a piece I’m preparing. But the biggest assumption of all is — they absolutely have to be right about methane. The people worried about methane say we could see on the order of 30 GtC, as methane, emitted in the next few decades.

That number is still within the reputed “budget” … until you consider the enhanced GWP of methane. Multiplied by 85 (the GWP of methane in the first 20 years), 30 Gt of atmospheric methane has the same warming effect as more than 250 GtC in CO2 form. Oops. No budget left.

Now consider that a mass release of methane could cause heating that causes … another mass release of methane, and so on. No one knows how these things might be connected. Do you feel lucky?

I’ll be writing a lot more about this mythical carbon budget. The money that can be made from future emissions is the one thing holding up all negotiations. The carbon-heavy countries and carbon-rich companies want the “budget” to exist and be large. The heavy carbon users — like India, China and the like — also want it to exist and be large. They think they can “win the century” by burning it. (Hint: No one will win the century if they burn it. Human civilization will begin its collapse.)

Do you want it to exist at all, this monetizable “carbon budget,” if it means only ⅔ chance that your grandchildren will not be hunter-gatherers? Do you want to make David Koch, worth over $50 billion at last count, even richer, with a rapid future loss of civilization as a downside? After all, David Koch will be dead by then, and we’ll be living in the world we let him leave to us. Something to think about.

GP

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Gaius Publius is a professional writer living on the West Coast of the United States.

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