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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The recent increase in methane has come from wetlands. I'd been under the impression that wetlands were less likely to cause methane escalation than destabilizing undersea methane hydrates.

Wetlands likely to blame for atmospheric methane increases: Study

A surprising recent rise in atmospheric methane likely stems from wetland emissions, suggesting that much more of the potent greenhouse gas will be pumped into the atmosphere as northern wetlands continue to thaw and tropical ones to warm, according to a new international study.

Scientists have assumed that wetland methane release is largest in the tropics, said Turetsky.

"But our analyses show that northern fens, such as those created when permafrost thaws, can have emissions comparable to warm sites in the tropics, despite their cold temperatures. That's very important when it comes to scaling methane release at a global scale."

... small temperature changes can release much more methane from wetland soils to the atmosphere. But whether climate change will ramp up methane emissions will depend on soil moisture, said Turetsky.

Under warmer and wetter conditions, much more of the gas will be emitted. If wetland soils dry out from evaporation or human drainage, emissions will fall -- but not without other problems.

... drying peatlands can spark more wildfires. [emphasis mine]

image source

Control methane now, greenhouse gas expert warns

Robert Hogwarth warns against the US pursuit of natural gas. Methane accounts for over 40% of current radiative forcing, and natural gas is the largest methane source in the US.

Robert Howarth, greenhouse gas expert and ecology and environmental biology professor, fears that we may not be many years away from an environmental tipping point – and disaster.

“We have to control methane immediately, and natural gas is the largest methane pollution source in the United States,” said Howarth,...

Howarth points to “radiative forcing,” a measure of trapped heat in Earth’s atmosphere from man-made greenhouse gases. The current role of methane looms large, he says, contributing over 40 percent of current radiative forcing from all greenhouse gases,...

If society aggressively controlled carbon dioxide emissions, but ignored methane emissions, the planet would warm to the dangerous 1.5 to 2.0 degree Celsius threshold within 15 to 35 years. [emphasis mine]

‘Catastrophe’ Claim Adds Fuel to Methane Debate

Bobby McGill's summary is clear. If we don't stop using shale oil and natural gas NOW, we could reach 2°C warming in 15 to 35 years. Worst case, very serious Climate Change by 2029.

Howarth’s conclusion: Producing natural gas of any kind has a worse greenhouse gas footprint than burning coal and crude oil over a 20-year timeframe. In other words, the idea that natural gas is a “bridge fuel” between carbon-producing coal and clean renewable energy sources simply isn’t true, especially if natural gas is used for home heating, the study says.

The paper is the latest in a long line of recent studies suggesting that methane emissions from shale oil and natural gas production and distribution equipment is much greater than previously thought.

A study by researchers from Purdue and Cornell universities published in April showed that natural gas drilling could emit up to 1,000 times the methane previously thought.

... there’s enough evidence that the climate implications of methane emissions from oil and gas development could be catastrophic and that it’s important to act now.

If shale oil and gas methane emissions aren’t reined in quickly, the earth could warm a critical 2°C within 15 to 35 years, he said

In his paper, Howarth is adamant that replacing climate-changing coal with climate-changing natural gas does nothing to slow global warming.. [emphasis mine]

Excess methane is often burned off from oil and gas production and distribution systems.

Dr. Robert Howarth refutes the natural gas bridge-fuel myth.

Replacing coal, oil with natural gas will not help fight global war...

Both shale gas and conventional natural gas have a larger greenhouse gas footprint than do coal or oil, especially for the primary uses of residential and commercial heating.

"While emissions of carbon dioxide are less from natural gas than from coal and oil, methane emissions are far greater. Methane is such a potent greenhouse gas that these emissions make natural gas a dangerous fuel from the standpoint of global warming over the next several decades," said Dr. Howarth. "Society should wean ourselves from all fossil fuels and not rely on the myth that natural gas is an acceptable bridge fuel to a sustainable future."

image source

Mantle Methane? Who knew! Here's a Reddit discussion clarifying another source of Arctic methane hydrates.

NTE means "near term extinction". This discussion was in response to the recently discovered methane megaflare in the Laptev Sea. (summary here) (definition of "obduction")

BR: If the the tipping point to NTE appears to revolve around the release of methane, how much methane is there?

M: A lot. There appears to be a minimum of one and two times more methane than all of the fossil fuel carbon in sequestered the Earth's mantel.[1]

BR: How can that be? I mean if fossil fuel came from biomass, then where did all of the methane come from?

M: Mantle methane seems to be formed from the reduction of oceanic carbonates by water in the presence of iron oxides buried to depths of 100 km to 300 km in the Asthenosphere and at temperatures above 1200°C. This, of course, is a vast, non-organic or geologic methane, formed near the earth's mantel under a massive pressure and has been there for millennia. Thus, methane hydrates can be found all around the Earth, even off the continental shelf of the Gulf of Mexico.

But the Arctic is a focal point for the collision of tectonic plate subduction and obduction. Plate migration creates methane routes through new fractures in the earth's mantel, but the fractures have been sealed over by Arctic ice. For the first time in human history, the ice-sealed fractures are thawing. Methane is rising through the fractures and into the atmo­sphere.[2][3]

BR: If this were true, why has it not happen before?

M: It most likely has happened in the distant past. Approximately 65 million years ago the Earth went through a similar heating process. Of course, there were no humans at that time, so the most plausible explanation is the release of geologic methane.

discussion page

Last year extra methane came out of the Arctic from October to March, as a result of warm water incursions. It takes months for the warm water from the Pacific and Atlantic Oceans to arrive deep in the Arctic Ocean. This image shows that the 2014 warm water anomalies from the Bering Strait (on the left) and the Atlantic (on the right) are larger than last year.

Last year, methane emissions started to become huge in October and this lasted for some six months.

This year, there is even more ocean heat present, especially in the north Atlantic and the north Pacific. On September 29, 2014, methane levels as high as 2641 parts per billion were recorded and it looks like worse is yet to come.

Warm water extends from Laptev Sea to North Pole

A new study suggests that oceans warming from CO2 absorption could trigger a second - far worse - warming event two thousand years later, that lasts 200,ooo years.

Ancient Earth Warmed Dramatically After a One-Two Carbon Punch

... the authors argue that a release of methane from deposits below the seafloor would explain both the rate of change and the curious double pulses. This methane is normally safely locked away in a solid form called methane clathrate, but even an undersea landslide might have been enough to destabilize an area of the seafloor and unlock a vast clathrate deposit. That kind of event could have triggered the short-lived pulse of global warming before the main PETM event.

In response to this initial pulse, Earth’s oceans might have soaked up the excess atmospheric heat. If they did, though, it’s possible that this natural recovery mechanism triggered the main event. Warmer oceans can themselves destabilize clathrate deposits, which might explain where the second carbon pulse came from, says Wing. If this scenario is correct, it makes the PETM even more relevant to today—the oceans are warming up once more, and clathrate deposits below the seafloor are again beginning to destabilize. [emphasis mine]

Methane is leaking from permafrost offshore Siberia

New research indicates that permafrost in the West Yamal shelf is already leaking profoundly, and explosive methane gas hydrate release will likely occur when the water warms 2 degrees.

Portnov and his colleagues have recently published two papers about permafrost offshore West Yamal, in the Kara Sea.

When the ice age ended some 12 000 years ago, and the climate warmed up, the ocean levels increased. Permafrost was submerged under the ocean water, and started it´s slow thawing. One of the reasons it has not thawed completely so far, is that bottom water temperatures are low, some - 0,5 degrees .

It was previously proposed that the permafrost in the Kara Sea, and other Arctic areas, extends to water depths up to 100 meters, creating a seal that gas cannot bypass. Portnov and collegues have found that the West Yamal shelf is leaking, profoundly, at depths much shallower than that.

Significant amount of gas is leaking at depths between 20 and 50 meters. This suggests that a continuous permafrost seal is much smaller than proposed. Close to the shore the permafrost seal may be few hundred meters thick, but tapers off towards 20 meters water depth. And it is fragile.

"If the temperature of the oceans increases by two degrees as suggested by some reports, it will accelerate the thawing to the extreme. A warming climate could lead to an explosive gas release from the shallow areas."

Permafrost keeps the free methane gas in the sediments. But it also stabilizes gas hydrates,...

Gas hydrates contain huge amount of methane gas, and it is destabilization of these that is believed to have caused the craters on the Yamal Peninsula. [emphasis mine]

Strong currents facilitate methane's escape from Arctic seas.

"We found that strong, fluctuating, currents were common above methane seeps, meaning that methane-consuming bacteria may not be as effective for regulating emissions of methane to the atmosphere as previously thought,"... [emphasis mine]

Strong currents promote release of Arctic greenhouse gas

Methane erupts from a golf course pond in Canada close to the US border.

published June 25th, Indian Hills 2015 Gas Eruptions

Widespread wildfires in Alaska and Canada are also fueled, in part, by methane released from lakes, bogs and wet zones. Who even knew that bogs burned!

Unprecedented Fire Season Has Burned 11 Million Acres So Far For Al...

Frozen lands are thawing, liberating billions of tons of soil carbon as an ignition source for wildfires. And methane bubbling up from lakes, bogs, and wet zones in the soil itself provides yet more tinder for a rapidly developing Arctic fire trap.

What the hell is wrong with this picture? Here we have a bog fire burning away in Saskatchewan, Canada on July 1st, 2015. The bright white color of the smoke is indicative of water vapor mixing in. Due to permafrost thaw, both bogs and related themokarst lakes have been emitting higher and higher volumes of methane over recent years. Methane that could well serve as a volatile fuel for fire ignition over wetlands like the one shown above. [emphasis mine]

Arctic Methane Alert — Ramp-Up at Numerous Reporting Stations Shows...

Canada methane graph shows atmospheric methane increases in the range of 20 parts per billion in just one year. This rate of increase is 2-3 times the global average for the past five years.

The curves in the graphs are steepening, hinting at a growing release of methane from a warming Arctic environment.

[From June, 2015.] The methane release curve is getting steeper.




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