Arctic Armageddon or Methane Madness?
Like an overly familiar maniac from a series of Hollywood slasher movies, CO2 has lost most of its ability to scare the public. Carbon dioxide's diminishing fright mojo has sent climate change alarmists—and those in the media who lend them mindless support in trade for salacious headlines—casting about for a next gas molecule to scare the public with. A few trial balloons have been floated for oxides of nitrogen (NOx) but the rising star in the global warming shop of horrors is methane (CH4). Aside from having a familial relation ship with CO2 based on carbon, CH4 is a known greenhouse gas and is produced almost everywhere on Earth by decaying organic matter. Most recently, there were panicked warnings that Arctic seabed methane stores were being destabilized. The hype over methane has gotten so out of hand that a news focus article in Science (which is not a hot bed of climate change skepticism) has publicly stated the situation is being exaggerated.
In an article title “'Arctic Armageddon' Needs More Science, Less Hype,” Science staff writer Richard A. Kerr, who is definitely in the warmist camp, makes the case for a bit of restraint when it comes to reporting on all things methane. Citing some recent examples of over heated methane reporting, Kerr offered this to cool down the rhetoric:
With bubbles of methane streaming from the warming Arctic sea floor and deteriorating permafrost, many scientists are trying to send a more balanced message. The threat of global warming amplifying itself by triggering massive methane releases is real and may already be under way, providing plenty of fodder for scary headlines. But what researchers understand about the threat points to a less malevolent, more protracted process.
You know things are getting crazy when the official journal of the AAAS, a long time cheerleader for the IPCC, urges restraint. Why all the fuss? Methane is a powerful greenhouse gas, estimated by the IPCC to be 30 times as potent as CO2. And it degrades into CO2, which accumulates in the atmosphere just as fossil fuel CO2 does. Naturally, newly discovered CH4 emissions has the global warming crowd all a twitter. A brief survey of some typical news stories, and the papers they were based on, reveals a trend toward the bombastic by the press.
“Massive methane release sparks global warming fears,” trumpeted TGDaily online. This based on a warning from the University of Alaska, Fairbanks (UAF). “The amount of methane currently coming out of the East Siberian Arctic Shelf is comparable to the amount coming out of the entire world's oceans,” said Natalia Shakhova, a researcher at UAF's International Arctic Research Center.
“Subsea permafrost is losing its ability to be an impermeable cap,” she concluded. The researchers involved took exhaustive samples over the East Siberian Arctic Shelf (ESAS) and found pervasive methane-rich waters, as they reported in the March 5, 2009, issue of Science. They claim their work “demonstrates that greater than 80% of ESAS bottom waters and greater than 50% of surface waters are supersaturated with methane regarding to the atmosphere.”
The US National Science Foundation has declared Arctic methane to be leaking off Siberian shores at an alarming rate. “Methane Releases From Arctic Shelf May Be Much Larger and Faster Than Anticipated,” was the March 4, 2010, press release headline.
Methane is leaking from the East Siberian Arctic Shelf into the atmosphere at an alarming rate.
According to the NSF, the permafrost of the East Siberian Arctic Shelf (an area of about 2 million square kilometers) is more porous than previously thought. The ocean on top of it and the heat from the mantle below it warm it and make it perforated like Swiss cheese. This allows methane gas stored beneath it under pressure to burst into the atmosphere. The amount leaking from this locale is comparable to all the methane from the rest of the world's oceans put together.
In another 2009 Science article, “Shifting Gear, Quickly,” E. G. Nisbet and J. Chappellaz warned that Earth's climate can quickly swing between sharply warming or fiercely cooling. “Past shifts of this kind were massive, and some took place within a few years,” they state. “About 11,600 years ago, at the end of the Younger Dryas cold period, the planet warmed very suddenly, with strong increases in atmospheric greenhouse gases, especially methane.”
Studies show this interval began with a 12°F (7°C) drop in temperature, in the span of only 20 years (measured in Greenland). More interestingly, the end of the Younger Dryas was marked by a period of rapid temperature increase—8°C (15°F) in a decade or less and an estimated 27°F (15°C) rise over half a century. That rapid rise exposes the claim that recent temperature increases have been “unprecedented” for the lie it is. A visual comparison of these changes and more recent temperature variation can be seen in Illustration below, taken from The Resilient Earth.
The cause of a large increase of atmospheric methane concentration around the time of the Younger Dryas has been the subject of much debate in paleoclimate circles. In the same issue of Science, Vasilii V. Petrenko et al. report that “corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas–Preboreal CH4 rise.”
Substantial amounts of the greenhouse gas methane can reach the surface ocean from seafloor seeps as deep as 600 metres, reported a 2009 paper in Nature Geoscience. Those results indicated that current estimates of the global flux of methane from the oceans to the atmosphere may be too low. In “Considerable methane fluxes to the atmosphere from hydrocarbon seeps in the Gulf of Mexico,” Evan A. Solomon et al. direct submersible sampling of deepwater (550–600 m) hydrocarbon plumes in the Gulf of Mexico.
“We show that bubble size, upwelling flows and the presence of surfactants inhibit bubble dissolution, and that methane oxidation is negligible,” they reported. “Consequently, methane concentrations in surface waters are up to 1,000 times saturation with respect to atmospheric equilibrium.” Previous results, based on modeling and traditional indirect sampling techniques, suggested methane bubbles emitted from marine seeps at depths greater than 200 m (650 ft) do not reach the surface because of bubble dissolution and methane oxidation.
Solomon et al. suggest that seeps in similar active hydrocarbon basins, such as the Persian Gulf, Caspian Sea, West African Margin and the Alaska North Slope, should be investigated more closely to improve estimates of the global methane flux from the oceans to the atmosphere. But perhaps the biggest threat comes from a form of methane trapped in ice—methane hydrate, the ice that burns.
No one is sure exactly how much hydrate exists worldwide, but it is on the order of several trillion metric tons. That's easily 1000 times the amount of methane presently in the atmosphere. Methane hydrate melts if it gets too warm, and it floats in water. A huge release of methane from hydrates is thought to have caused the PETM, a period of intense global warming 55 million years ago. Tsunami causing underseas landslides have also been blamed on destabilized hydrate beds.
According to Kerr, a far stronger case for incipient hydrate destabilization appeared last year with less fanfare. In a paper in the August 6, 2009, issue of Geophysical Research Letters (GRL) , marine geophysicist Graham Westbrook and colleagues described how they used sonar to probe the shallow waters just west of Norway's Svalbard archipelago—halfway between mainland Norway and the North Pole. Bottom waters in the area reportedly have warmed by 1°C (1.8°F) during the last 30 years, warming naturally being attributed to global warming. The researchers found plumes of methane bubbles rising from the bottom in places where warm currents contact the Svalbard seafloor.
Modeling results reported in GRL on December 15, 2009, by hydrogeologists Matthew Reagan and George Moridis of Lawrence Berkeley National Laboratory, bottom-water warming melted the hydrates and released methane along the edge of a deteriorating hydrate deposit, much as seen off Svalbard. “That seems like the strongest argument for hydrates releasing methane as they are warmed,” says Archer. The threat from hydrate deposits could be sever, since such deposits are found world wide. As unstable as deposits of methane hydrates are made out to be, some people are actively trying to mine the seafloor to recover the gas.
In truth, science really doesn't have a good understanding of methane, where it is produced and under what conditions it can be released into the atmosphere. In a perspective article in the July 16, 2010, issue of Science, entitled “The Ongoing Mystery of Sea-Floor Methane,” Marc Alperin and Tori Hoehler discuss recent studies of a rare but intriguing sedimentary environment—sea-floor seeps of methane-rich fluids. First they addressed our current level of understanding.
Each year, ocean sediments produce a quantity of methane equivalent to about half of the methane emitted to the atmosphere from all natural sources (1). Very little of the methane produced below the sea floor, however, reaches the ocean or the atmosphere; most is consumed by anaerobic microorganisms as it diffuses up through oxygen-poor (anoxic) sediments. Researchers recognized this process, known as anaerobic methane oxidation (AMO), nearly 35 years ago, but it remains poorly understood. Investigators have not been able to firmly establish the reaction mechanism, fully understand the factors that control oxidation rates, or isolate the responsible organisms. This represents a gaping hole in our understanding of one of Earth's primary sinks for methane.
With a “gaping hole” in our knowledge, it seems a bit premature to declare methane the new global despoiler. Once again, when existing models are applied to the little studied environments around seafloor seeps, the answers generated are “orders of magnitude too high.” The reviewers concluded that microorganisms may process methane by different mechanisms in quiescent ocean sediments (A) and dynamic methane seeps (B).
In (A), methane oxidation is most active at the interface between the sulfate reduction zone (yellow) and the methane production zone (green). Here, methane oxidation is best explained by a methanogenic archaea (red) that oxidize methane to CO2 and H2, and sulfate-reducing bacteria (green) that consume H2 working in tandem.
In contrast, at seeps (B) methane processing appears to be most active in near-surface sediments and involve aggregates of methanogen-like archaea (red) and sulfate-reducing bacteria (green). Here, archaea may be engaged in methane oxidation coupled to sulfate reduction through interspecies electron transfer. This could be facilitated by conducting filaments, or by methane production fueled by organic matter fermentation. I thought the question mark next to the possible chemical transformations was a nice touch.
“Solving the sea-floor methane mystery will involve studies that integrate microbiological and geochemical approaches across these two distinct environments,” conclude the authors, adding “if the past is any guide, we may be in for some surprises.” Indeed.
Not all reports involve an increase in methane emissions. Recently, a decrease in atmospheric methane was attributed to human predation of paleolithic megafauna. Supposedly, bands of human hunters killed off mammoths, mastodons and other large grazing animals soon after the end of the last glacial period (see “Mammoth Confusion”). This altered the ground coverage of what had been grasslands, causing warming according to one group, while at the same time reducing methane emissions from the defunct herbivores.
An early methane abatement program in action.
Is an Arctic Armageddon caused by methane just around the corner? Perhaps. But judging from the latest surprise discoveries and the admitted gaping holes in our understanding, climate scientists are in no position to make a believable prediction. Methane and all claims of dangerous global warming need more science and less hype. Earth may not be poised on the brink of Armageddon, but many climate scientists and news reporters are suffering from methane madness.
Be safe, enjoy the interglacial and stay skeptical.