Methane’s Contribution to Global Warming Is Worse than You Thought

It seems we've been "fudging the numbers" in a sense, when comparing the global warming potential of methane to CO2. When global warming potential (GWP) of a gas is calculated, a time frame is assumed. The IPCC decided to use a 100 year time frame.

With a 100 year time frame methane heats up the planet 21 times as much as CO2. The problem with that assumption is that we don't have 100 years. A 20 year time frame would be much more realistic, given the urgency of climate crisis. With a 20 year time frame...

... any CH4 released today is at least 56 times more heat-trapping than a molecule of C02 also released today. And because of the way it reacts in the atmosphere, the number is probably even higher, according to research conducted by  Drew Shindell , a scientist at NASA’s Goddard Space Center. [emphasis mine]

 

What if we were to use the IPCC’s 20-year comparison instead of its 100-year comparison? For starters, it would force us to get much more serious about tackling  the sources of methane emissions. Here in the US, the top methane sources are the decomposition of wastes in landfills, agriculture (from ruminant digestion), and leaks from natural gas drilling and transmission. A new emphasis on methane would require us to get smarter about capturing methane at landfills, reduce the market incentives that encourage Americans’ meat-heavy diets, and ensure that methane isn’t leaking from fracking operations.

But beyond the policy specifics, adopting the 20-year global warming potential comparisons would be useful for changing how we think about climate change.

And we appear to be approaching some irrevocable tipping points that will create powerful negative feedback loops, the most worrisome being  the release of methane  stores at the bottom of the ocean and locked into sub-Arctic permafrost.

Image from Arctic Methane Release Tipping Point Diagram
With 56 times as much warming as CO2 in mind, we'd take this feedback more seriously.

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Replies to This Discussion

Trembling Tundra is a new feature of thawing permafrost, from bubbles of methane and carbon dioxide  under the surface.

Trembling tundra - the latest weird phenomenon in Siberia's land of...

Earth is moving as 'leaking methane gas due to global warming causes surface to bubble' in a new phenomenon.

This extraordinary sight - in a video filmed of the tundra on remote Belyy Island in the Kara Sea off the Yamal Peninsula coastline - was witnessed by a scientific research expedition. Researchers Alexander Sokolov and Dorothee Ehrich spotted 15 patches of trembling or bubbling grass-covered ground.

When punctured they emitted methane and carbon dioxide,...

OH! These people might be standing on or puncturing the edge of a gigantic blast waiting to happen. I wonder if they went back to follow up and see if there was a hole where they stood? 

Bermuda Triangle disappearances explained by methane hydrate explosions!

Large undersea craters from methane hydrate release are found in various places worldwide. This isn't new. The hypothesis that a ship above such a release would sink, based on the sudden drop in ocean density which would result, is also not new. This comes to prominence now as scientists who've studied the Yamal craters take a fresh look at subsea possibilities. Take "new theory" with a grain of salt. Also, it would be extraordinarily unlikely someone could document such an event, and live to share it. So  take "there is no evidence to show that this has actually ever happened" with a grain of salt too.

Bermuda Triangle mystery solved? Experts claim methane gas explosio...

Note: the video attached to the article appears to have no relevance.

... a new theory may have finally solved the mystery.

Earlier this year, several craters were discovered which piqued scientists' interest from around the globe.

Soon after it was discovered that the large holes in the ground were likely caused by the release of large amounts of gas beneath the surface in a process known as methane hydrates.

Now, experts believe that this phenomena may be the reason why air and water vessels go missing over the Bermuda Triangle,...

"It is very probable that the similar sinkholes in the ocean were produced [as a result] of decomposing gas hydrates.”

Benjamin Phrampus, an Earth scientist at Southern Methodist University in Dallas, added: "Gas hydrate is known to exist along the U.S. North Atlantic continental margin, with a very large province on Blake Ridge (north of the Bermuda Triangle).”

A study back in 2003 confirmed that these bubbles arising from the deep ocean are capable of sinking ships, but Mr Phrampus said that there is no evidence to show that this has actually ever happened.

Yamal craters

Mysterious Siberian crater attributed to methane
Build-up and release of gas from thawing permafrost most probable explanation, says Russian team.

Katia Moskvitch

31 July 2014

The crater in the Yamal peninsula in Siberia is 30-metres wide.

Siberian Times wrote on February 23, 2015 that:

Examination using satellite images has helped Russian experts understand that the craters are more widespread than was first realized, with one large hole surrounded by as many as 20 mini-craters …

Now, you should be able to zoom in and see sinkholes. 
In geology, Karst topography is a landscape formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves.

A close-up look resembles Karst topography, however, I don't think the term fits here. The methane does not drain away, it evaporates. Is there a term for that? Or is it just "sinkhole"?

We've found another uncounted source of atmospheric methane: meltwater from the Greenland Ice Sheet.

Ice sheet deglaciation and methane emissions, with the scope on Gre...

The findings indicate that methanotrophs could serve as a biological methane sink in the subglacial ecosystem. Scaled dissolved methane flux during the 4 months of the summer melt season was estimated at 990 Mg CH4. Because the Russell-Leverett Glacier is representative of similar Greenland outlet glaciers, the researchers concluded that the Greenland Ice Sheet may represent a significant global methane source.

The good news is that methane eating bacteria in the subglacial ecosystem could absorb some.

More bad news from April. Retreating polar ice sheets can destabilize the gas hydrate stability zone, leading to accelerated methane release.

By analogy [to the area studied], the future response of Polar ice sheets is an emerging concern as their ongoing thinning and retreat will likewise perturb the present day subglacial GHSZ (gas hydrate stability zone) leading to potential widespread gas hydrate destabilisation and release.

Methane release this Summer at Barrow Alaska, via Brian Brettschneider.

Preliminary findings from the current expedition to measure methane release in Laptev Sea aren't good.

The findings come from an expedition now underway led by Professor Igor Semiletov, of Tomsk Polytechnic University, on the research vessel 'Academic M.A. Lavrentyev' which left Tiksi on 24 September on a 40 day mission. 

The seeping of methane from the sea floor is greater than in previous research in the same area, notably carried out between 2011 and 2014. 

'The area of spread of methane mega-emissions has significantly increased in comparison with the data obtained in the period from 2011 to 2014,' he said. 'These observations may indicate that the rate of degradation of underwater permafrost has increased.'

The team are examining how the ice plug that has hitherto prevented the exit of huge reserves of gas hydrates has today 'sprung a leak'. [emphasis mine]

Arctic methane gas emission 'significantly increased since 2014' - ...

Methane release is ramping up on the East Siberian Shelf.

Increasing Methane Releases in Arctic Proven by International Exped...

"We reached and examined about 20 stations which had been measured earlier and each one showed the releases increasing. To underline that methane mega releases – with the area of over 1 km – are registered only at the East Siberian Shelf,” said ... Igor Semiletov.

Update on East Siberian Arctic Shelf methane:

1. Scientific Article - Current rates and mechanisms of subsea permafrost degradation in th...

2. Easier-to-grasp interviews - Current rates and mechanisms of subsea permafrost degradation in th....

The rate of subsea permafrost melt in the near-shore zone of the East Siberian Arctic Shelf has been measured. A "downward movement of the ice-bonded permafrost table of  about 14 cm/year over the past 31–32 years" means the melted layer is 14 cm deeper each year

The bottom line is those reassuring studies saying methane dissolves out of rising bubbles and that methane hydrate deposits were overestimated are now irrelevant to an assessment of our danger.

Shakhova and Semiletov found that 10% of the East Siberian Shelf are now hotspots, where methane release to the atmosphere is 3 to 5 orders of magnitude higher. Non-hotspot areas release 3 milligrams per square meter per day, while hotspot areas release 3,000 grammes per square meter per day. 

This is exactly what is the difference between the linear and exponential. 

Even if methane hydrate deposits don't explode, the way pingos have been doing on nearby land, a gigaton release could occur by growing hotspot areas. They measured the top of the undersea permafrost at zero degrees C. 

The overriding issue is the vast majority of stored methane (99% if I read correctly) is stored as free gas under high pressure within deep sediments.

Dr. Shakhova: The importance of hydrates involvement in methane emissions is overestimated. 

... the layer of hydrates composes just few hundred of meters – ... compared to thousands of meters of underlying gas-charged sediments in the ESAS.

Dr. Semiletov ...the 5 billion tonnes of methane that is currently in the Earth’s atmosphere represents about one percent of the frozen methane hydrate store in the East Siberian Arctic Shelf. He finishes emphasising “…but we believe the hydrate pool is only a tiny fraction of the total.”

So, only about 1% of the methane which warming could release from the ESAS will come from methane hydrate. The volume of methane-saturated sediment is gigantic.

This huge area is 2 million square kilometres. The depth of this sedimentary drape is a few kilometres, up to 20 kilometres at places. 

Unlike hydrates, this gas is preserved free; it is a pre-formed gas, ready to go. Over pressured, accumulated, looking for the pathway to go upwards.

In our observations, we have accumulated the evidence that this gas front is propagating in the sediments.

To me as a scientist, these points are enough to be convinced that methane release in the ESAS is related to disintegration of subsea permafrost and associated destabilisation of seabed deposits whether it is hydrates or free gas accumulations.

Because the shelf area is very shallow (mean depth is less than 50 metres), a fraction of these emissions will reach the atmosphere. The problem is that this fraction would be enough to alter the climate on our planet drastically.

Summing up:

  • The methane in our air at this time (5 billion tonnes) is about 1% of the amount stored as frozen methane hydrate in the East Siberian Arctic Shelf.
  • The methane in frozen hydrates is about 1% of the total stored methane, the remainder being gas under high pressure trapped in kilometers-deep sediment.
  • Free gas under pressure in sediment can create pathways for upward migration when undersea permafrost above it thaws, releasing to the air in hotspots. If hotspots continue to increase, as they have been seen to do from one expedition to the next, the release rates will increase exponentially. Even if water absorbs some of it, enough methane will likely escape to drastically alter the climate.

Consider a reply on Reddit:

Heard a recent interview with Peter Wadhams. He mentioned that in communication with shakhova preliminary results on quantifying ESAS release from their survey late last year. 6 months after this work. Anyway, indications are that it's currently releasing 8 times previous measurements from 2013 survey. Doubling time is now 12 months. [emphasis mine]

Scary! What kind of world will our grandchildren live in -- even if we could magically stop all of our greenhouse gas emissions (including methane from livestock) tomorrow? (Still better than if we continue the business-as-usual "cheap energy banquet with no consequences" thinking!)

On Reddit I asked if my summary (above) was correct. Consider this response from IndependentMale.

From the interview, that is correct. The ESAS region contains approx. ten thousand times more Methane than currently in our atmosphere.

Currently, Methane in our atmosphere contributes 28% of the total warming forcing over an atmosphere-less baseline.

In a radiative equilibrium without atmosphere but preserving the current albedo, the temp. of the Earth would be 1 degree C (approx.).

The current average temp. of the planet's surface is approx. 15 degrees C.

The difference is 14 degrees, to which the CH4 contributes 28%, or 4 degrees.

Ignoring all non-linear effects and the extreme initial forcing effect (estimated to be up to 500 x) of CH4, if one thousandth of this methane, 0.1 % of CH4 in the Arctic region would reach the atmosphere, then we'd see a temperature rise of (10,000 / 1000) * 4 = 40 degrees Celcius, arriving at an average planetary temperature of 55 degrees Celcius. Such a temperature is incompatible with multi-cellular life.

This is all just a back-of-the-envelope calculation, but it's accurate enough to show complete extinction of practially all life on our planet in case a tiny fraction of Methane escapes. That dieoff would happen near-instantaneously (within days, weeks or at most a few seasons, in certain locations) if that 0.1% would escape instantaneously.

Since we've warmed up the average planetary temperature by, depending on who you believe, conservatively 5% by now from the thermal equilibrium baseline, it stands to reason that this 5% increase is very significant, seen the fact that 0.05% CH4 outgassing from the ESAS (a thousand times less than we've been heating up the globe), even when over a 100 year time period, would kill us all - as it has before, when the great majority of species went extinct when increased CO2 lead to increased CH4. This time, it will happen much faster though.

My conclusion: It's a matter of when, not if before the Earth reaches Venus-level temperatures, unless we find technological solutions such as using the 2nd generation emDrive (superconducting version) to bring huge reflective sails into orbit. We can't put anything in a geostationary orbit over the poles though, which is where they're direly needed. But we could orbit such albedo-increasing devices nevertheless. emDrive v.2 would cost orders of magnitude less, for mass-to-orbit, than SpaceX's reusable booster technology. [emphasis mine]

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