New Research Mitigates Methane Fears

February 20, 2020

Good news.
It’s mostly us that is killing ourselves.

And we can stop that.
Can’t we?

(also backs up my recent videos on the “methane bomb” scare)

Scripps Institute – UC San Diego:

A long-feared scenario in which global warming causes Arctic permafrost to melt and release enough greenhouse gas to accelerate warming and cause catastrophe probably won’t happen.

That is the conclusion of a study, appearing Feb. 21 in the journal Science, that began more than 20 years ago as a query posed by Jeff Severinghaus, a geoscientist at Scripps Institution of Oceanography at the University of California San Diego. A research team led by the University of Rochester that includes Severinghaus analyzed samples of gases trapped in ice during a period of deglaciation between 18,000 and 8,000 years ago. That period is considered an analogue for the current era of global warming. 

The researchers conclude that even if methane is released from permafrost and other stores known as methane hydrates, very little actually reaches the atmosphere.

“It is a rare piece of good news about climate change,” said Severinghaus, who began pursuing the question in the 1990s, “so I’m happy to come to the public and say this burp is something we don’t have to worry about.”

Severinghaus said the study is bolstered by its reliance on a definitive source of data. Measurements of the carbon-14 isotope are considered a reliable and unambiguous indicator of permafrost and hydrate methane. Because carbon-14 breaks down in 5,000 years on average, the much older carbon from permafrost and hydrate deposits contains virtually no carbon-14. 

University of Rochester graduate student Michael Dyonisius led the study with his advisor Vasilii Petrenko, a professor of earth and environmental sciences and former student of Severinghaus at Scripps Oceanography. Scripps Oceanography researchers Sarah Shackleton, Daniel Baggenstos, Ross Beaudette, Christina Harth, and Ray Weiss are among co-authors of the National Science Foundation and David and Lucille Packard Foundation-supported paper. 

When plants die, they decompose into carbon-based organic matter in the soil. In extremely cold conditions, the carbon in the organic matter freezes and becomes trapped instead of being emitted into the atmosphere. This forms permafrost, soil that has been continuously frozen—even during the summer—for more than one year. Permafrost is mostly found on land, mainly in Siberia, Alaska, and Northern Canada.

Along with organic carbon, there is also an abundance of ice in permafrost. When the permafrost thaws with rising temperatures, the ice melts and the underlying soil becomes waterlogged, helping to create low-oxygen conditions. That creates an ideal environment for microbes in the soil to consume the carbon and produce methane.

Severinghaus had first considered using carbon-14 to determine how much methane from ancient carbon deposits might be released to the atmosphere in warming conditions in the 1990s. He and his student Petrenko began pursuing the idea in 2001 and began collecting air samples in Greenland, but the task was not easy. Only about one part of methane exists in 1 million parts of air and only one out of every trillion parts of carbon is in the form of carbon-14.

The team drilled and collected ice cores from Taylor Glacier in Antarctica, where they could find purer air samples than those found in Greenland. Each contained bubbles with small quantities of ancient air trapped inside.  

The research for the present study led by Dyonisius focused on measuring the composition of air from the time of Earth’s last deglaciation, 8,000-15,000 years ago.

“The time period is a partial analogue to today, when Earth went from a cold state to a warmer state,” Dyonisius said, “but during the last deglaciation, the change was natural. Now the change is driven by human activity, and we’re going from a warm state to an even warmer state.”

The researchers concluded that the methane released does not reach the atmosphere in large quantities. They believe this is due to several natural “buffers,” such as methane-eating microbes in the top few inches of soil above permafrost that intercept the gas before it reaches the atmosphere.

“We can probably thank those little bacteria for saving our bacon,” Severinghaus said.

The data also show that methane emissions from wetlands increased in response to climate change during the last deglaciation, and it is likely wetland emissions will also increase as the world continues to warm today.

The good news about one source of methane is tempered by another report on modern-day methane emissions that was released Wednesday in the journal Nature.  The Nature study, co-authored by Severinghaus, Petrenko, Dyonisius, and many of the other contributors to the permafrost paper, concluded that human-caused fossil fuel methane emissions have been underestimated by as much as 40 percent. 

“Anthropogenic methane emissions currently are larger than wetland emissions by a factor of about two, and our data show that we don’t need to be as concerned about large methane releases from old carbon reservoirs in response to future warming,” said Petrenko.  “Instead we should be more concerned about the methane that is being released from human activities now.”

7 Responses to “New Research Mitigates Methane Fears”

  1. Tom Styles Says:

    The “deglaciation between 18,000 and 8,000 years ago” is not an appropriate analog for today. In that time interval continental glaciers melted away exposing the land beneath to the bitter cold of northern winters. The tundra biome shifted North into areas formerly covered by glaciers, accompanied by formation of permafrost, not thawing of it. The Eemian epoch of the earlier interglacial 130,000 years ago is a much better analog for our current situation. 14C in ice formed at that time needs to be looked at before anyone can truly breath a sigh of relief.

    • greenman3610 Says:

      no evidence of “methane bomb” in the Eemian.

      • Tom Styles Says:

        True, no evidence of a “bomb”, but Eemian methane release may have been a bigger factor than in the terminal Pleistocene to early Holocene analogy. A sophisticated 14C analysis of bubbles from ice of Eemian age would be even more useful I think. The Eemian was certainly interesting here in the lower Midwest USA: alligators in creeks around St. Louis, giant tortoises on the central Illinois plain. It was as though winter as we know it ceased to happen. Also the deep red Sangamon paleosol displayed in roadcuts in the region’s loess deposits indicates a climate and biological regime markedly unlike that which gave rise to our present day prairie soils. We really need a better understanding of how quickly Eemian conditions developed and how all factors contributed.

        • greenman3610 Says:

          The Eemian also had a different temp profile than our current interglacial, in that
          temperature spiked early, then plateaued for 10k years or so before cooling off.
          That’s quite different from today, where we’ve had a 10k year plateau, now moving into
          a big spike – so we could see a different response this time.
          As you say, always more research needed – but I think the “extinction in 10 years from
          the methane bomb” people need to step back at least for now.

  2. redskylite Says:

    More positive reinforcement to the sudden Arctic methane release unlikelihood (let’s hope that’s also mirrored in the Antarctic), as the lower latitudes catch up.

    So we need to concentrate on our massive industrial de-carbonization program, and keep a wary eye on the Keeling curve.

    “Global warming causing ‘irreversible’ mass melting in Antarctica”

    ” .. .. .the only thing that would slow down the ice melting was if economies across the world began de-carbonising themselves.

    According to a forecast published by Britain’s Met Office last month, the fires contributed to one of the biggest annual increases in the concentration of carbon dioxide in the earth’s atmosphere since record-keeping began more than 60 years ago.

    Still a question mark on Permafrost loss on the chart of tipping points, but less of a concern the the studies.

  3. indy222 Says:

    Ever since Randall pointed out the stability depth for methane hydrates was about 350m and far below Arctic Ocean bottom sediments, the “methane bomb” has been only a playground for the lunatic fringe like Guy McPherson.

    That says nothing about the methane released by wetlands globally but especially in the thawing Arctic bogs. And the “compost bomb instability” identified in recent years. We’re not out in the clear here.

    And, our own nat gas leaks are far worse than had ben thought and claimed by the nat gas industry (wow. They lied? Amazing!)

  4. dumboldguy Says:

    Hmmmm. First red wine, marijuana, eggs, chocolate, were bad for us—-but then some of them weren’t—–then some of them were again. I get so confused!

    Now there will be no methane bomb and we shouldn’t be scared? Until the next study and then we should? As I said, I get so confused—maybe it’s a sign of old age?—-my next birthday will be my 80th (I think).

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