Study: Arctic ocean ‘methane bomb’ really isn’t anything to worry about

From the UNIVERSITY OF ROCHESTER comes this study that backs up a study that we reported on just a few days ago about methane clathrates on the ocean floor. The so-called Arctic “methane bomb” that some off the rails climate scientists have been worrying about just isn’t going to happen.

Release of ancient methane due to changing climate kept in check by ocean waters

Ocean sediments are a massive storehouse for the potent greenhouse gas methane.

Trapped in ocean sediments near continents lie ancient reservoirs of methane called methane hydrates. These ice-like water and methane structures encapsulate so much methane that many researchers view them as both a potential energy resource and an agent for environmental change. In response to warming ocean waters, hydrates can degrade, releasing the methane gas. Scientists have warned that release of even part of the giant reservoir could significantly exacerbate ongoing climate change.

However, methane only acts as a greenhouse gas if and when it reaches the atmosphere–a scenario that would occur only if the liberated methane travelled from the point of release at the seafloor to the surface waters and the atmosphere.

With that in mind, environmental scientist Katy Sparrow ’17 (PhD) set out to study the origin of methane in the Arctic Ocean.

“While a logical suspect for arctic methane emissions is degrading hydrates, there are several other potential methane sources. Our goal was to fingerprint the source of methane in the Arctic Ocean to determine if ancient methane was being liberated from the seafloor and if it survives to be emitted to the atmosphere,” says Sparrow, who conducted the study, published in Science Advances, as part of her doctoral research at the University of Rochester.

Sparrow; her advisor, John Kessler, an associate professor of earth and environmental sciences; and a team of scientists from the Universities of Rochester, California Irvine, Minnesota Duluth, and Colorado Boulder, as well as the US Geological Survey and the National Oceanic and Atmospheric Administration, conducted fieldwork just offshore of the North Slope of Alaska, near Prudhoe Bay. Sparrow calls the spot “ground zero” for oceanic methane emissions resulting from ocean warming.

Ice and snow formations at the mouth of Sag River emptying into Prudhoe Bay, Alaska. Rochester researchers conducted fieldwork just offshore of the North Slope of Alaska, near Prudhoe Bay, calling the spot “ground zero” for oceanic methane emissions resulting from ocean warming. (Getty Images photo)

In some parts of the Arctic Ocean, the shallow regions near continents may be one of the settings where methane hydrates are breaking down now due to warming processes over the past 15,000 years. In addition to methane hydrates, carbon-rich permafrost that is tens of thousands of years old–and found throughout the Arctic on land and in seafloor sediments–can produce methane once this material thaws in response to warming. With the combination of the aggressive warming occurring in the Arctic and the shallow water depths, any released methane has a short journey from emission at the seafloor to release into the atmosphere.

The researchers used radiocarbon dating to fingerprint the origin of methane from their samples. By employing a technique they developed that involves collecting methane from roughly ten thousand gallons of seawater per sample, they made a surprising discovery: ancient-sourced methane is indeed being released into the ocean; but very little survives to be emitted to the atmosphere, even at surprisingly shallow depths.

“We do observe ancient methane being emitted from the seafloor to the overlying seawater, confirming past suspicions,” Kessler says. “But, we found that this ancient methane signal largely disappears and is replaced by a different methane source the closer you get to the surface waters.” The methane at the surface is instead from recently produced organic matter or from the atmosphere.

Although the researchers did not examine in this study what prevents methane released from the seafloor from reaching the atmosphere, they suspect it is biodegraded by microorganisms in the ocean before it hits the surface waters. Mihai Leonte, a PhD candidate in Kessler’s research group, observed this process–in which microbes aggressively biodegrade methane as methane emissions increase–in a paper published last year.

“We found that very little ancient methane reaches surface waters even in the relatively shallow depths of 100 feet. Exponentially less methane would be able to reach the atmosphere in waters that are thousands of feet deep at the very edge of the shallow seas near continents, which is the area of the ocean where the bulk of methane hydrates are,” Sparrow says. “Our data suggest that even if increasing amounts of methane are released from degrading hydrates as climate change proceeds, catastrophic emission to the atmosphere is not an inherent outcome.”

Sparrow and Kessler’s results on the role of ancient methane sources are consistent with the findings of their Rochester colleague Vasilii Petrenko, an associate professor of earth and environmental sciences, who also radiocarbon dated methane. However, while Sparrow and Kessler dated methane found in modern-day seawater, Petrenko radiocarbon dated methane from the ancient atmosphere that was preserved in the ice of Arctic glaciers.

“Petrenko and his co-authors studied a rapid warming event from the past that serves as a modern-day analog,” Sparrow says. “They found that the emissions of methane from ancient methane sources during this warming event were minimal relative to contemporary sources like wetlands.”

Kessler adds, “Our results agree with this conclusion, showing that ancient methane emissions to the atmosphere in an area that is experiencing some of the greatest warming today, is actually quite small, especially when compared to more direct emissions from human activities.”


This study was primarily funded by the National Science Foundation with additional contributions from the Department of Energy, the National Aeronautics and Space Administration, and the University of Minnesota.

The paper: (open access)

Limited contribution of ancient methane to surface waters of the U.S. Beaufort Sea shelf


In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.


47 thoughts on “Study: Arctic ocean ‘methane bomb’ really isn’t anything to worry about

  1. Very interesting and appears to be solid objective science – for a pleasant change.

    It also makes basic sense. In an environment that harsh and limited one would expect any potential nutrient to be used by something. Can’t let all that vintage methane go to waste.

    Microorganisms saved the planet!

    • Yes, it does seem to be based on real field research, rather than sitting in a nice warm room and running fantasy climate models. In fact the word “model” doesn’t even appear in the report, which is extremely unusual.

    • I disagree; the purpose of the paper appears to be obfuscation.

      “Oceanic oxidation” converts the CH4 into CO2, which readily reaches the atmosphere. The authors will never examine the source of carbon in the CO2, as they must never acknowledge that much of the earth is covered with temperature-sensitive carbonaceous sediments, as they must never admit that increasing CO2 above present concentrations has no significant effect on atmospheric temperature.

      • … they must never admit that increasing CO2 above present concentrations has no significant effect on atmospheric temperature.

        I don’t see how that follows. What part of their theory demands that CO2 does or does not cause global warming?

        What I do see is a temperature dependant source of CO2 that is unaccounted for in CO2 budgets. To attribute the increase in CO2 to humans, ‘they’ have to be able to do their accounting within 1%.

        It’s complicated. Murry Salby says “that at least 2/3 of the observed increase in atmospheric CO2 is natural and temperature induced.” A temperature dependant source of CO2 bolsters his position.

      • commieBob:

        The insensitivity of atmospheric temperature to a change in the present concentration of CO2 does not follow from this study. Instead, I suggest that this study results from a perceived need to explain why the “methane bomb” that must exist if there is significant “climate sensitivity” has not gone off already.

      • If the methane was oxidized to CO2 by the ocean, CO2 does not “readily reach the atmosphere”, but reacts with water to form carbonic acid, H2CO3. While global-warming scaremongers claim that CO2 dissolving in seawater (from the atmosphere) could “acidify” the oceans, ocean water contains many dissolved salts (particularly calcium salts) which form a “buffer solution” that can precipitate out excess CO2 or carbonic acid as carbonates and bicarbonates, many of which are used by mollusks and crustaceans for their shells. This removal of carbonates tends to reduce the impact of dissolved CO2 on the pH (alkalinity) of the oceans.

        This buffering effect of the salts dissolved in ocean water has been extensively researched by Professor James Barrante in Connecticut, who has published many articles on this subject.

    • Microorganisms have made the planet what it is. A life-friendly place. Without microorganisms, the blue planet would not exist! We have to pay more respect to the world of bacteria, fungi and small animals. The world would be an uninhabitable place without the constant interplay of these microorganisms.

    • I wish they focused more on the actual critters under water using the methane. I find arctic life fascinating, because nothing goes to waste. They used to think the Arctic Ocean was sterile away from the coasts, but since have learned it is teeming with life, as the underside of the ice (like a fouled boat-bottom) creates an ecosystem southern oceans lack. Much to learn about, up there.

  2. A scientist who avoided the easy path to popularity by claiming it was us what did it! Refreshing and a great credit to honesty and objective science.

  3. Sparrow says. “They found that the emissions of methane from ancient methane sources during this warming event were minimal relative to contemporary sources like wetlands.”

    Drain the swamps.

    • It is not about if those tipping points exist, it is the very talk about tipping points. A fuzzy scare story does not need a detailed theory. It is even more scary if you can claim ‘scientists don’t know’ or that they’re ‘puzzled’.

  4. Oil & Gas. Entirely natural products. And biodegradable.

    Seems to tick all the enviro-friendly marketing boxes to me. What’s not to like?

    • The ultimate goal of the likes of Al Gore and Michael Mann is to have their descendants live in large castles as the super elite masters of their fifes, while the remaining humans that haven’t starved due to their policies live a hunter gatherer existence, and give offerings to these living ‘gods’. In shorter words, they hate modern civilization and will do anything to destroy it, ie communism.

  5. The previous interglacial period, the Eemian, was warmer than the current one and no runnaway waming due to more greenhouse gases because of the warming ever happened. For those that believe in the radiative greenhouse effect, by far the dominant greenhouse gas is H2O and warmer temperatures and warmer oceans cause more H2O to enter the atmosphere and runnaway warming caused by more H2O entering the atmosphere has never occoured. Compared to the effects of H2O, the presence of the other greenhouse gases is insignificant.

    • So you say but I think awful lot believes in multiplication factor 2 or greater, so that 1 degree of theoretical CO2 warming causes more than 2 degrees warming in practice. We need to wait for this question to be resolved. And it is a real scientific dispute.

      • Who cares who believes what? We aren’t in the business of belief. We are in the business of evidence. Someone is going to have to provide evidence supporting the hypothesised amplification. There is no sign of it in the geological record and the current hiatus observational data argues strongly against it, as does the missing mid-tropospheric hot spot. Even common sense argues strongly against it or there is an astronomically tiny chance the water-world we call Earth would have remained relatively thermally stable over the aeons if it were subject to strong positive feedback from water vapour. They cannot simply keep claiming their hypothesis is correct without supporting evidence and flying n the face of evidence which refutes the hypothesis.

        How long are we expected to go along with this bizarre pseudoscientific charade before the normal procedures of the scientific method are once again restored? It amuses me to be castigated at whiles for not taking the ‘debate’ seriously enough or giving sufficient respect to the eminent scientists on the other side of the ‘debate’. From my perspective there is absolutely nothing to debate until some evidence – and by evidence I don’t mean model output and mangled data – is presented and ridicule is all that is left.

      • You can get the 2C of warming per doubling by looking directly at the concentration versus the temperature rise and extrapolating. This assumes that all warming is due to CO2. It’s not the best supported estimate, but it’s far from the worst.

      • Besides being a so called greenhouse gas, H2O is a major coolant in the Earth’s atmosphere mobing heat energy from the Earth’s surface which is mostly some form of H2O to where clouds form via the heat of vaporization. The fact that the wet lapse rate is significantly less than the dry lapse rate is physical evidence that more H2O has a cooling rather than a warming effect so the feedback of more H2O in the atmosphere must be negative.

        One researcher has found that the original calculations of the climate sensivity of CO2 ignored the fact that a doubling of the amount of CO2 in the Earth’s atmosphere will cause a slight decrease in the dry lapse rate in the troposphere which is a cooling effect and decreasesing the climate sensivity of CO2 by more than a factor of 20.

        There is no real evidence in the paleoclimate record that CO2 has ever affected climate.

    • Because lower troposphere water vapor cools the surface and increases albedo. It increases thermal conductivity of the atmosphere through virga.

      Methane clathrates are stabilized by pressure far more than they are dissociated by increasing temperature.

      • it seems that the more we know the less we understand. We will adapt to whatever the planet throws at us.

  6. The source of “ancient methane” is not identified and how it dissipates is not identified!

    So we don’t know where it came from and don’t know where its going!

  7. Someone should spoil their little party and show them a graph of MSL during the LGM ~20 Kyr ago. The North Slope continental shelf was dry land.
    And that cycle of shallow water-dry land in her cherished “ground zero” has been repeated how many times over the last 3 Myrs? Something like 30+ times IIRC.

  8. Increasing sea level should add “cover depth” over clathrate deposits as well as incrementally increasing the pressure over them to maintain them in their present state. So, does increasing sea level actually REDUCE the likelihood of methane emission?

    • It’s just one of the myriad examples of what happens when you have a non-hypothesis which is supposed to explain everything through variance of a single insignificant parameter. You would think they would know that the only outcome of this madness is endless paradoxes but I guess things have progressed so far away from science and into the magisterium of religion that they simply don’t care about such trivialities when faith is what is important.

    • Depends on whether the level rises because of new water (ice cap melting), or if it rises because of reduced density because of higher temperature.
      The first will increase mass and pressure, the second doesn’t add mass nor pressure.

  9. It’s a relief to read something that makes some sense.

    The article mentioned wetlands and swamps. Wetlands and swamps are future peat bogs, which are future coal veins. It takes many, many (300) millions of years to form a coal vein.

    I hope that none of the CAGWers get the bit in their teeth over that.

  10. This ‘methane bomb’ zombie fact is easily the most insidious of all. I’ve had discussions with normally rational well respected scientists – admittedly not in the physical sciences – who immediately go into a frenzy of pure bulging-eyed terror over it. It is the great granddaddy of Thermageddon doom scenarios which literally unhinges nominally rational minds. There is nothing you can do to deflect it. Any attempt to calmly point to previous warm periods in which there were no ‘methane bombs’ going off and sterilising the planet is met with hysteria, shouting, spittle-flecked purple jowls bouncing up and down and wild-eyed accusations of denile etc etc. It would be funny if it weren’t for the real genuine extreme distress of those afflicted with the gullibility gene.

    • It’s not just gullibility – issues like this allow these “scientists” to shed the image of dull men working in offices and instead to play the part of Old Testament Prophets shouting “DOOM! DOOM!!!” This gives them a great deal of social status, and when you point out the ridiculousness of their “fears”, what you are really doing is threatening their precious social status – so of course they react with rage directed at YOU.

      Also, it points out how most average working class people actually have a much better intuitive understanding of how the world works than many of these so-called “scientists” do. Average people don’t walk around worrying about methane hydrates, and neither should they.

  11. Given all the problems with trying to radio carbon date anything in water, I’d like to know a little bit more about how they know the methane is from ancient sources.

  12. Yes, well that’s probably then end of their careers…. I’m guessing that next time they ask for funding. They won’t get any.

  13. As noted by Bo. Steve and cephusO above.

    Le Chatelier’s principle applies here. The zone of stability for natural gas
    hydrates is mediated by both temperature and pressure. The same is true
    of CO2.

    As the earth cools, the sea level drops, so the hydrates which might have been
    released by dropping sea level are held in place by cooler temperatures.
    The reverse is true in warming oceans. Rising sea levels tend to increase
    the pressure side of the curve while reducing the temperature influence
    side of the curve. See zone of stability link below.

    Mostly, the hydrate becoming a gas is the result of pressure of gas upwelling
    gas from below. The resistance to nat gas upwelling is similar to a champagne
    bottle cork in that there is a limit to the amount of pressure it can contain. The
    hydrate itself becomes the stopper when the gas hits the cold/deep ocean.
    When it is liberated, it becomes a gas, it is usually eaten by microbes, oxidized,
    and either is retained in the seawater if the seawater is below saturation,
    and later precipitated, or rises to the atmosphere as a gas.

    CO2 in water has a zone of stability mediated by temperature, pressure,
    precipitation, and gasification.

    The USGS site is bigoted in that it refers only to methane, when
    in fact is natural gas, the better to convince people that it is a fossil
    fuel, but it does refer to inferred hydrates on other planets. See link on
    natural gas below.

  14. The phase diagrams I could find in my five minute search show hydrates only form below about 300 meters at 0°C. These researchers are looking at methane produced or seeping from much shallower water. It is unlikely for the source to be hydrate since it does not have sufficient pressure to form at that shallow depth. If it were present deep in the silt layers (deep enough that the silt provides the pressure – perhaps 150 meters), it will be too warm for it to form. Unless the temperature much deeper is increasing significantly, hydrates are not decomposing into water and methane.

  15. Even a significant fraction of the global warmers don’t buy into the methane thing. Too much of the IR spectrum overlaps with water, and the atmospheric half life before oxidative-removal is too short for armageddon to be achieved. Release all of the methane tomorrow and it will have a modest effect which is then gone in a few years to decades.

    This is also why they like, and need, to make exaggerated claims for CO2 residence time: If they admit that residence time is short then humanity can always wait and see, with plenty of time to find a solution if it really does turn out to be a problem. Some “problems” in life really can be solved by simply ignoring them and waiting. And if there is one thing greens truly hate, it is viable simple and cheap solutions to their imagined problems.

  16. I watch this debate over which things that will warm the planet are happening of if they are not and I think to myself “who the f’k cares?”. When I was a kid I lived in an apartment right on the beach. Now I am half a century old and I am working in that same town. The apartment, the beach and the water are all exactly where they were when I was a kid. So my question is what is the actual damage happening? Not more extreme weather because that never really materialized. No melted ice caps. Even if sea level is rising it is doing so at such a slow pace that it really doesn’t make any difference. The buildings will get old enough to need to be replaced before the water will overtake them. If the sea level is higher when that happens then they will just build in a different spot or build something like a seawall. I could see worrying about it if we were getting 10 feet per decade or something crazy like that but so far in my life I can’t tell the difference between then and now.

  17. The whole clathrate catastrophe thing has never made sense to me. Oceans just do not warm at depth in the arctic. The ice may melt a bit earlier or a bit later in the season, but regardless what happens at the surface the temperature at depth there is constant all year round. Even if global warming were to warm the ocean depths somehow by some unexplained mechanism the increase in pressure due to the hypothesised rise in ocean levels would compensate. I just don’t see any realistic scenario that would lead to a significant release of arctic clathrates. And even if somehow the methane was released, its lifetime in the atmosphere is too short to be catastrophic.

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