Recently we’ve linked to a couple of scary posts, ie. The Methane Threat and Warning of mass extinction of species, including humans, within one decade, both at the Arctic News blog.
This is alarming to say the least.
The first thing I did was look up the Climate Plus archives tag for Methane.
My post of June 2015 Dealing with the methane time bomb is still worth reading.
I concluded then that the scientists appeared to be divided between methane alarmists and methane gradualists. There was great uncertainty about how much methane is stored, especially under the ocean, and whether it will be released rapidly enough to cause alarm. Methane is over 100 times more potent as a greenhouse gas than CO2 over the first five years, but then degrades to about 20 times more potent after 130 years. At that time atmospheric methane was 1900 parts per billion. CO2 accounts for about 80% of the greenhouse gas effect, with methane the second most significant greenhouse gas, according to NASA accounting for one-sixth of global warming.
Much of the alarm at that time had been generated by Natalia Shakhova of the University of Alaska at Fairbanks and her team, which had been studying the Arctic release of methane for 30 years. They published a paper in 2010 which calculated the effect of releasing 3% of the total store of methane in a 5-year period. They found that the extra methane would lead to additional warming of 1.3°C. They said it could happen, not that it would.
In December 2015 in Climate clippings 161 #6 I linked to a Scientific American article which reported that more methane was being emitted from the Arctic than previously thought. The principal finding was that the methane kept emitting, albeit at a lower rate, during the winter period. Half the methane emitted was released between September and May. Previously it had been assumed that methane was only released in the summer. Obviously, monitoring during the winter is fraught.
- CSIRO researcher Dr Pep Canadell said it was the most comprehensive modelling to date and revealed a potentially dangerous climate wildcard.
“Methane emissions were stable for quite a few years at the end of the 2000s. But they’ve begun to grow much faster, in fact 10 times faster, since 2007,” said Dr Canadell, who is also the executive director of the Global Carbon Project.
Here is the relevant graph of growth since 2005:
The graph shows the possible trajectory for all the IPCC climate scenarios, with the black line showing actual observations.
However, the main concern in that report was not with the Arctic, rather with agriculture, and within that enteric fermentation from ruminants and manure.
Methane clathrates in the Arctic were erupting in concentrated plumes, which were missed by measuring stations and satellites. From the troposphere they spread to the equator, where the methane was wrongly assumed to come from tropical wetlands. This image showed a profile of the circulation systems.
That article was from Arctic News. The article outlines what seems to be a theory posited by blog editor Sam Carana. No scientific paper is referred to and no mention is made of the fact that methane source can be distinguished by isotopic signatures, mentioned below.
At this point I’ll say that I’m a touch uneasy about the scientific solidity of what I read there. The blog authors listed seem to be well-qualified in science, but I’m not sure that any are actively researching the Arctic release of methane. From the blog, they are certainly methane alarmists.
For example, take this diagram which shows the mechanism whereby heat attacks the clathrates:
First of all, I can see no reason why the thickness of the ice cover should of itself make any difference to how heat in the water below behaves.
They may be on a better wicket when in this post from 2014 they assert that a warm tongue of water from the Gulf Stream penetrated the deeper water of the Arctic Ocean. That is the same Gulf Stream that we worry about slowing down or stopping.
The Gulf Stream is a surface current on its way north and may be bringing warmth to the shallower clathrates in the Arctic basin.
A less alarming article March 2016 article from NASA. Methane sourced from clathrates at that time constituted about one per cent of emissions. There is masses of the stuff down there, that much now seems to be agreed, but:
- most gas hydrate—about 99 percent—is sequestered in deep-water environments where temperatures are cold enough and the pressures are great enough for the deposits to remain stable. Most of these deep-water deposits lay buried beneath layers of sediment, so even if global warming continues for thousands of years, it would probably have little effect on them.
Just a small portion of gas hydrates (about 3.5 percent) occurs at depths where warming ocean waters may be causing the methane hydrate to break down, sending methane bubbling up. However, methane released underwater still rarely reaches the atmosphere directly. Microbes on the ocean floor and living within the water column usually consume it or convert it into carbon dioxide first.(Emphasis added)
As such some can then be absorbed into the water column on the way up.
Carolyn Ruppel, is or was chief of the U.S. Geological Survey’s gas hydrate program.
- Just 1 percent of methane hydrates are found at very shallow depths under Arctic permafrost, either on land or just offshore. On land, even the shallowest methane hydrates are still deeply buried by sediments so gas cannot escape easily. In shallow marine areas, methane hydrates could break down with warming, Ruppel notes, but deposits in this region represent such a small percentage of the overall methane hydrate stores that the climate impact would be minimal.
“We certainly will not see the catastrophic climate effect or runaway climate change from disintegrating gas hydrates that some have claimed,” said Ruppel.
More recently from NOAA in October 2016 we have a press release Study finds fossil fuel methane emissions greater than previously estimated.
The study led by scientists from NOAA and CIRES found that:
fossil fuel activities contribute between 132 million and 165 million tons of the 623 million tons of methane emitted by all sources every year. That’s about 20 to 25 percent of total global methane emissions, and 20 to 60 percent more than previous studies estimated.
They say that methane emissions have distinct isotopic signatures that distinguish whether a sample came from fossil fuel development and natural geologic sources, microbial activity, or biomass burning.
Isotopic analysis points to natural or human-caused microbial sources as the source of between 364 million to 419 million tons of methane per year, or 58 to 67 percent of methane released to the atmosphere each year, Schwietzke said. Total methane emissions from all sources increased by about 28 million tons per year between 2007 and 2013.
“We believe methane produced by microbial sources – cows, agriculture, landfills, wetlands, and fresh waters – are responsible for the increase, but we cannot yet pinpoint which are the primary drivers,” he said. “If the methane is mainly coming from cows or ag, then we could potentially do something about it. If it’s coming from decaying vegetation in wetlands or fresh waters, then a warming climate could be the culprit, which means that it could be part of a self-reinforcing feedback loop leading to more climate change. Those are big ifs, and we need to figure them out.”
Joining in the fun, with an alarmist post on 14 April just passed we have Julian Cribb on his blog with Early warning of a runaway climate.
Cribb is a science writer. His latest book Surviving the 21st Century: Humanity’s Ten Great Challenges and How We Can Overcome Them is one I’d like to read. I did a post on it last December. However, he is distinctly alarmist on methane and I wonder about his objectivity.
For example, he says “scientists report a sudden surge in global methane emissions in the last three years, 2014-16.” If you follow the link you get an article by M Saunois et al, The growing role of methane in anthropogenic climate change. From the abstract:
- New analysis suggests that the recent rapid rise in global methane concentrations is predominantly biogenic-most likely from agriculture-with smaller contributions from fossil fuel use and possibly wetlands.
- Russian scientists have reported the discovery of thousands of potential ‘methane-bombs’ – frozen gas-filled mounds known as pingos – across Siberia, primed to explode as the ground thaws out.
The link takes you to an article from September 2015 which, while expressing concern, specifically says that it’s premature to talk about a global catastrophe. No mention is made of much of the methane being chewed by microbes and coming out as CO2, which I covered in my June 2015 post.
Then he says:
- Swedish scientists have observed the waters of the Arctic oceans ‘fizzing like soda water’ as the ocean currents warm, causing frozen seabed methane to turn back into gas and erupt.
The link is to a better post about new plumes of methane found in research led by the Swedes in a particular place just as they were wrapping up their research in August 2014. Peter Wadhams, an Arctic News author, is revealed as the one who did the calculations about a possible release of 3% of the total store of methane in a 5-year period mentioned further up.The short answer is that was dealt known and dealt with when I wrote the June 2015 post and is not now news.
Most naughty of Cribb, he lists a link for further reading without mentioning it which turns out to be an article Could Subsea Methane Hydrates Be a Warming “Tipping Point”? based on an interview with Carolyn D. Ruppel and John D. Kessler who had just written a paper The interaction of climate change and methane hydrates.
The paper says that there is some “dissociation” happening now on global upper continental slopes and on continental shelves that ring the Arctic Ocean, but there is no conclusive proof that any of the methane gas released makes it to the surface. The answer in the interview about methane hydrates being a global warming tipping point is an emphatic “no”.
That was published the day before Cribb’s blogpost.
Cribb does publish a useful graph, sourced from NOAA, showing the rise of methane emissions:
Uncertainties abound in how methane is monitored and no-one is sure just where the extra methane is coming from. However, methane coming from ocean clathrates and permafrost come from a very low base:
Sorry, I’ve lost the source, but it was from a recent paper. The numbers add up to 678 million tonnes, so it’s a recent number. Scientific critics of the Arctic methane catastrophe thesis worry that it distracts from dealing with sources of emissions that we can do something about. This graph, apparently from 2011 in the 2016 NASA article (you would think they has something more recent) shows past and future of anthropogenic methane emissions:
Enteric fermentation is mainly about sheep and cattle, and gas is mainly about fugitive emissions associated with the gas industry. Gas as a ‘clean’ energy source needs to come under more attention.
While there does not appear to be a warrant for suggesting that methane may render Homo sapiens extinct within a decade, the sad fact is that, as the World Meteorological Association’s State of the Climate 2016 (see Climate clippings 201 #2) shows, emissions in the form of CO2, methane and nitrous oxide are not only increasing relentlessly, but the rate of increase is rising:
We are forcing the climate system harder than it was forced in the Paleocene–Eocene Thermal Maximum (PETM) 55 million years ago, or even in the Great Dying, the Permian-Triassic extinction event 252 million years ago. The circumstances were entirely different, the Earth was a different place, with a different starting temperature, the continents were differently distributed and the ocean currents would have been different. Nevertheless we should not be surprised if we run into an unexpected tipping point or two which could render warming irreversible in human time-scales. That’s what dangerous climate change is about.
Update: See also later post