Projected carbon emission (in billions of tons of carbon a year) from thawing permafrost. From a 2011 NOAA/NSIDC study with moderate warming and other conservative assumptions.
The good news: The best NOAA analysis “suggests we have not yet activated strong climate feedbacks from permafrost and CH4 hydrates.” Climate Progress first reported that finding 2 years ago. The lead author of that work confirms to CP it still remains true — despite the fact that methane levels have been rising for the past 5 years after a decade of little growth.
The bad news: Leading experts at NOAA, the National Snow and Ice Data Center and around the world now expect the permafrost to become a major source of atmospheric carbon in the next few decades (see “NSIDC/NOAA: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100” and “Nature: Climate Experts Warn Thawing Permafrost Could Cause 2.5 Times the Warming of Deforestation!”)
NY Times science reporter Justin Gillis has just published an excellent overview article, “As Permafrost Thaws, Scientists Study the Risks.” The piece makes clear we may be near a tipping point, citing University of Alaska scientist Vladimir Romanovsky:
In northern Alaska, Dr. Romanovsky said, permafrost is warming rapidly but is still quite cold. In the central part of the state, much of it is hovering just below the freezing point and may be no more than a decade or two from widespread thawing.
That thawing is of great concern because the permafrost contains a staggering amount of carbon, as Nature reported:
The latest estimate is that some 18.8 million square kilometres of northern soils hold about 1,700 billion tonnes of organic carbon4 — the remains of plants and animals that have been accumulating in the soil over thousands of years. That is about four times more than all the carbon emitted by human activity in modern times and twice as much as is present in the atmosphere now.
The permafrost carbon thus represents a dangerous amplifying feedback or vicious cycle whereby warming leads to accelerated emissions, which leads to further warming. And that could lead to a point of no return, as Gillis reports:
In the minds of most experts, the chief worry is not that the carbon in the permafrost will break down quickly — typical estimates say that will take more than a century, perhaps several — but that once the decomposition starts, it will be impossible to stop….
That’s especially true since sea ice loss in the Arctic is happening faster than every major climate model projected — and accelerated Arctic warming and permafrost loss was linked to ice loss in a 2008 study by leading tundra experts, “Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss”:
We find that simulated western Arctic land warming trends during rapid sea ice loss are 3.5 times greater than secular 21st century climate-change trends. The accelerated warming signal penetrates up to 1500 km inland and is apparent throughout most of the year, peaking in autumn. Idealized experiments using the Community Land Model, with improved permafrost dynamics, indicate that an accelerated warming period substantially increases ground heat accumulation. Enhanced heat accumulation leads to rapid degradation of warm permafrost and may increase the vulnerability of colder permafrost to degradation under continued warming. Taken together, these results imply a link between rapid sea ice loss and permafrost health.
And, of course, recent analysis suggests that our current “no policy” approach to climate will lead to staggering Arctic warming this century (see M.I.T. doubles its 2095 warming projection to 10°F — with 866 ppm and Arctic warming of 20°F).
So by any objective measure, the recent science and observations of the permafrost are increasingly worrisome.
While the NY Times’ Gillis gets this right in the print edition, NYT blogger Andy Revkin asserts in a post published 3 days earlier focused on sea-based methane hydrates, “There’s an entirely different set of questions, also with relatively reassuring answers, about the vast amounts of methane locked in permafrost on land.” Not!
The NYT would seem to be schizophrenic on this crucial topic, but Gillis clearly has the story right and it isn’t reassuring at all.
Indeed, Gillis adds some new reporting that is very un-reassuring:
A troubling trend has emerged recently: Wildfires are increasing across much of the north, and early research suggests that extensive burning could lead to a more rapid thaw of permafrost.
Let’s look at the highlights of the important Gillis piece before returning to the sea-based issue:
Preliminary computer analyses, made only recently, suggest that the Arctic and sub-Arctic regions could eventually become an annual source of carbon equal to 15 percent or so of today’s yearly emissions from human activities.But those calculations were deliberately cautious. A recent survey drew on the expertise of 41 permafrost scientists to offer more informal projections. They estimated that if human fossil-fuel burning remained high and the planet warmed sharply, the gases from permafrost could eventually equal 35 percent of today’s annual human emissions.
The experts also said that if humanity began getting its own emissions under control soon, the greenhouse gases emerging from permafrost could be kept to a much lower level, perhaps equivalent to 10 percent of today’s human emissions.
Even at the low end, these numbers mean that the long-running international negotiations over greenhouse gases are likely to become more difficult, with less room for countries to continue burning large amounts of fossil fuels.
In the minds of most experts, the chief worry is not that the carbon in the permafrost will break down quickly — typical estimates say that will take more than a century, perhaps several — but that once the decomposition starts, it will be impossible to stop.
“Even if it’s 5 or 10 percent of today’s emissions, it’s exceptionally worrying, and 30 percent is humongous,” said Josep G. Canadell, a scientist in Australia who runs a global program to monitor greenhouse gases. “It will be a chronic source of emissions that will last hundreds of years.”
Are you relatively reassured yet?
The article has a nice graphic (click to enlarge).
When the Tundra Burns
Gillis has some important reporting on a related amplifying feedback
One day in 2007, on the plain in northern Alaska, a lightning strike set the tundra on fire.
Historically, tundra, a landscape of lichens, mosses and delicate plants, was too damp to burn. But the climate in the area is warming and drying, and fires in both the tundra and forest regions of Alaska are increasing.
The Anaktuvuk River fire burned about 400 square miles of tundra, and work on lake sediments showed that no fire of that scale had occurred in the region in at least 5,000 years.
Scientists have calculated that the fire and its aftermath sent a huge pulse of carbon into the air — as much as would be emitted in two years by a city the size of Miami. Scientists say the fire thawed the upper layer of permafrost and set off what they fear will be permanent shifts in the landscape.
Up to now, the Arctic has been absorbing carbon, on balance, and was once expected to keep doing so throughout this century. But recent analyses suggest that the permafrost thaw could turn the Arctic into a net source of carbon, possibly within a decade or two, and those studies did not account for fire.
“I maintain that the fastest way you’re going to lose permafrost and release permafrost carbon to the atmosphere is increasing fire frequency,” said Michelle C. Mack, a University of Florida scientist who is studying the Anaktuvuk fire. “It’s a rapid and catastrophic way you could completely change everything.”
Gillis points outs:
The essential question scientists need to answer is whether the many factors they do not yet understand could speed the release of carbon from permafrost — or, possibly, slow it more than they expect.
For instance, nutrients released from thawing permafrost could spur denser plant growth in the Arctic, and the plants would take up some carbon dioxide. Conversely, should fires like the one at Anaktuvuk River race across warming northern landscapes, immense amounts of organic material in vegetation, soils, peat deposits and thawed permafrost could burn.
I’ve written about the peat issue recently (see “Stunning Peatlands Amplifying Feedback — Drying Wetlands and Intensifying Wildfires Boost Carbon Release Ninefold: “Drying of northern wetlands has led to much more severe peatland wildfires and nine times as much carbon released into the atmosphere, according to new research”).
I would add that denser plant growth in the Arctic might not actually be such a good thing — because of reduced snow cover and albedo (reflectivity). According to a 2008 Science article: “Continuation of current trends in shrub and tree expansion could further amplify [Arctic] atmospheric heating 2–7 times.” The point is that if you convert a white landscape to a boreal forest, the surface suddenly starts collecting a lot more solar energy (see “Tundra 3: Forests and fires foster feedbacks“).
The point is that if you convert a white landscape to a boreal forest, the surface suddenly starts collecting a lot more solar energy.
And then we have the study, “Frequent Fires in Ancient Shrub Tundra: Implications of Paleorecords for Arctic Environmental Change,” which finds:
… greater fire activity will likely accompany temperature-related increases in shrub-dominated tundra predicted for the 21st century and beyond. Increased tundra burning will have broad impacts on physical and biological systems as well as on land-atmosphere interactions in the Arctic, including the potential to release stored organic carbon to the atmosphere.
The concern is not so much the direct emissions from burning tundra. As the article concludes: “studies of modern tundra fires suggest the possibility for both short- and long-term impacts from increased summer soil temperatures and moisture levels from altered surface albedo and roughness, and the release soil carbon through increased permafrost thaw depths and the consumption of the organic layer.”
Gillis ends his piece:
Edward A. G. Schuur, a University of Florida researcher who has done extensive field work in Alaska, is worried by the changes he already sees, including the discovery that carbon buried since before the dawn of civilization is now escaping.
“To me, it’s a spine-tingling feeling, if it’s really old carbon that hasn’t been in the air for a long time, and now it’s entering the air,” Dr. Schuur said. “That’s the fingerprint of a major disruption, and we aren’t going to be able to turn it off someday.”
There is nothing reassuring in the least about recent permafrost research and observation.
It is widely believe that some of the carbon locked away in the tundra will be released as methane, a very potent greenhouse gas. Gillis notes:
If a substantial amount of the carbon should enter the atmosphere, it would intensify the planetary warming. An especially worrisome possibility is that a significant proportion will emerge not as carbon dioxide, the gas that usually forms when organic material breaks down, but as methane, produced when the breakdown occurs in lakes or wetlands. Methane is especially potent at trapping the sun’s heat, and the potential for large new methane emissions in the Arctic is one of the biggest wild cards in climate science.
Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 times to 100 times as potent over 20 years! The new Nature study found:
Across all the warming scenarios, we project that most of the released carbon will be in the form of CO2, with only about 2.7% in the form of CH4. However, because CH4 has a higher global-warming potential, almost half the effect of future permafrost-zone carbon emissions on climate forcing is likely to be from CH4. That is roughly consistent with the tens of billions of tonnes of CH4 thought to have come from oxygen-limited environments in northern ecosystems after the end of the last glacial period.
And because of the much higher warming impact of methane over shorter time frames, even this low percentage level of methane means that over a 20 year period, the warming from CH4 will actually be higher than that of CO2.
Because methane is so potent and because of the recent literature on the Arctic warming and tundra melt, many have wondered whether the Arctic is responsible for the recent resurgence in global methane levels. Here is the latest data from The NOAA Annual Greenhouse Gas Index:
As you can see, methane levels are on the march again after almost a decade.
Back in 2009, I wrote about a NOAA-led study, Dlugokencky et al., “Observational constraints on recent increases in the atmospheric CH4 burden” (subs. req’d, NOAA online news story here), which found:
The most likely drivers of the CH4 anomalies observed during 2007 and 2008 are anomalously high temperatures in the Arctic and greater than average precipitation in the tropics. Near-zero CH4 growth in the Arctic during 2008 suggests we have not yet activated strong climate feedbacks from permafrost and CH4 hydrates.
But then we seemed to get some reports that suggested that Arctic methane hydrates could be a source of the continuing surge (see my March 2010 post here). The lead author of an NSF-funded study said on the Eastern Siberian Arctic Shelf said, “Our concern is that the subsea permafrost has been showing signs of destabilization already. If it further destabilizes, the methane emissions may not be teragrams, it would be significantly larger.” The NSF warned, ““Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.”
And then this month, we had the UK’s Independent writing a story on the work of Russian scientist Igor Semiletov of the International Arctic Research Centre at the University of Alaska Fairbank, “Shock As Retreat of Arctic Sea Ice Releases Deadly Methane Gas Levels.”
But Dlugokencky emails that his work through 2010 confirms:
There is no evidence from our atmospheric measurements that there has been a significant increase in emissions during the past 20 years from natural methane sources in the Arctic so far.
And, as Revkin notes, a new study finds, “Siberian shelf methane emissions not tied to modern warming” (subs. req’d). That study suggests the offshore methane hydrates are unlikely to be a big contributor to methane emissions this century.
I tend to think all bets are off after 2100 if we are idiotic enough to stay on our current emissions path (see Science stunner — On our current emissions path, CO2 levels in 2100 will hit levels last seen when the Earth was 29°F (16°C) hotter).
I wanted to probe further, so I interviewed Stephen Wofsy of Harvard University. He has been flying on NSF’s research plane HIAPER (for High Performance Instrumented Airborne Platform for Environmental Research) as part of the HIPPO (for HIAPER Pole-to-Pole Observations) pollution mapping program.
Science News had written this back in September:
Something too new to fully understand (although a report on it is being prepared for publication), Wofsy says, is a finding of notable concentrations of methane in the Arctic’s atmosphere that trace back to the sea.
“Oceanographers have known for some time that there is production of methane in surface waters of the Arctic,” he says, but “it’s never been observed in the atmosphere.” Those oceanographic data, he says, suggest a source for this methane other than sediments or the melting of icy gas hydrates.
The phenomenon also appears very widespread. “We observed that the ocean surface releases methane to the atmosphere all over the whole of the Arctic Ocean,” Wofsy says.
Climate scientists have been concerned about whether the Arctic Ocean’s loss of summer ice cover might lead, through some feedback mechanisms, to boosting the release of methane. Concludes Wofsy: Thanks to HIPPO, “This hypothesized feedback has been observed for the first time.” And there are hints, he adds, that methane’s source may be something other than melting of gas hydrates.
According to Wofsy, HIPPO saw significant methane fluxes over the Arctic ocean away from the shore — but this “wasn’t seen where the ice is solid.” He thinks it is probably due to micro-organisims munching anaerobically. And he thinks that the retreat of the ice increases the productivity of the micro-organisims and allows more of the methane to escape.
He doesn’t think this will “blow the world up,” but he does think it is a significant effect and could increase as the ice retreats. He’ll be describing his findings in more detail in a forthcoming Journal article.
The key conclusion remains unchanged from my October 2009 post, “Is it just too damn late?” We have not crossed a tipping point or point of no return with methane releases in the Arctic. It’s not too late to avert the worst impacts of human-caused global warming. But what we now know that wasn’t so clear back then is that the best science and the leading scientists say we are likely to see large releases of carbon from the permafrost this century — particularly if we don’t aggressively reduce greenhouse gas emissions starting ASAP.
The stunning conclusion of the NOAA/NSIDC paper was:
The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate…. [Our] estimate may be low because it does not account for amplified surface warming due to the PCF itself….
We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42–88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration.
The Nature article concludes:
Our group’s estimate for carbon release under the lowest warming scenario, although still quite sizeable, is about one-third of that predicted under the strongest warming scenario.
… our survey outlines the additional risk to society caused by thawing of the frozen north, and underscores the urgent need to reduce atmospheric emissions from fossil-fuel use and deforestation. This will help to keep permafrost carbon frozen in the ground.
The only thing recent research on the Arctic reassures us about is the urgent need to cut emissions sharply and quickly.
This post has been updated (to replace “algae” with “micro-organisms”).