by Don Wharton
The state of scientific knowledge on arctic methane is profoundly disturbing. The scientists talk about how much they don't know but then the seeming consensus is that that there a high confidence that there is no risk of a substantial game changing Artic methane release. This is on its face contradictory. If they don't know then they don't know.
Topics to be covered:
1. Current sharp rise in methane from pre-industrial times.
2. Extreme lack of current information on Arctic methane release.
3. Thermal shock to climate system preceding at unprecedented rate.
4. Known mechanisms that can significantly increase transport of ocean methane to the atmosphere.
5. A known mechanism that can significantly ease the release of land methane deposits.
6. A known mechanism which can significantly magnify the impact of methane that is released.
There is a great many discussions about anomalously high methane readings from the modest tracking that is done. Readings of 200 to 900 ppb above normal readings seem to be given the charming term dragon breath. The standard readings for methane seem are now approaching 1900 ppb which is over 2.5 times the 721 ppb assumed for pre-industrial times. This can be seen from the graphs included here:
There is a current five year program to fly planes over Alaska, called CARVE. There seems to a gross discontinuity between the initial reports that were disturbing and the initial final report which is sanguine:
Quoting one paragraph, “Some of the methane and carbon dioxide concentrations we've measured have been large, and we're seeing very different patterns from what models suggest," Miller said. "We saw large, regional-scale episodic bursts of higher-than-normal carbon dioxide and methane in interior Alaska and across the North Slope during the spring thaw, and they lasted until after the fall refreeze. To cite another example, in July 2012 we saw methane levels over swamps in the Innoko Wilderness that were 650 parts per billion higher than normal background levels. That's similar to what you might find in a large city."
Of course, with the radically increased warming in the Arctic during the summer we are seeing many more small lakes being formed which can nourish the methane brewing bacteria that feed on the massive amounts of organic material in the permafrost. It is easy for the frozen water from the permafrost when thawed to migrate to the slightly lower levels and form these very shallow swamps/lakes.
There are recent maps posted by NASA on these CARVE flights which show the significant differences in CO2 and methane levels along the flight paths for the planes:
Compare the disturbing evidence above with the formal announcement,
NASA: Alaska Shows No Signs of Rising Arctic Methane:
The title conveys the very sanguine message. However, read especially the last paragraph in the following quote from news release:
“Alaska composes about one percent of Earth's total land area, and its estimated annual emissions in 2012 equaled about one percent of total global methane emissions. That means the Alaskan rate was very close to the global average rate.
"That's good news, because it means there isn't a large amount of methane coming out of the ground yet," said lead author Rachel Chang, formerly at Harvard University, Cambridge, Massachusetts, and now an assistant professor and Canada Research Chair in Atmospheric Science at Dalhousie University, Halifax, Nova Scotia.
Charles Miller of NASA's Jet Propulsion Laboratory, Pasadena, California, the principal investigator for CARVE, noted that results from a single year cannot show how emissions might be changing from year to year. "The 2012 data don't preclude accelerated change in the future," he said.
Vast amounts of carbon are stored in undecayed organic matter -- dead plants and animals -- in Arctic permafrost and peat. Scientists estimate that there is more than twice as much carbon locked in the frozen North as there is in the atmosphere today. The organic material won't decay and release its carbon as long as it stays frozen. But climate change has brought warmer and longer summers throughout the Arctic, and permafrost soils are thawing more and more. If large amounts of undecayed matter were to defrost, decompose and release methane and carbon dioxide into the atmosphere, the impact on global temperatures would most likely be enormous.
In fact the message in the title of this news release reflects ignorance. Since the researchers did not know the prior rate of methane release they can say that there are no signs of methane increase. That clearly does not provide evidence that there is no increase. The fact is that there is massively greater organic material being thawed each year and the starkly high “dragon breath” readings are unlikely to have existed in a past when permafrost actually remained frozen.
The rate of increase in global warming gasses is preceding at a pace that has never been equaled in the history of our planet. This may provide a thermal shock to the climate that has never occurred in the past. Even during the very extreme Permian extinction it is unlikely that the rate of climate change equaled what we are going through now.
David Archer is a respected climatologist and is seen as someone who does an excellent job in debunking climate change deniers. He very much supports the majority of climate scientists who do not see any catastrophic release of Arctic methane. I have read over 100 pages of his detailed discussion on the topic including this one:
My recollection is that many dismissive discussions of methane rising from the ocean floor talks about how most of the methane will dissolve in the water and be eaten by bacteria. However, Archer discusses a research piece that calculated a 50 year half life in the ocean. Quoting from the above link:
“Rehder et al. (1999) inferred an oxidation lifetime of methane in the high-latitude North Atlantic of 50 years.
An oxidation lifetime of 50 years leaves plenty of time for methane gas to evaporate into the atmosphere. Typical gas exchange timescales for gas evasion from the surface ocean would be about 3–5m per day. A surface mixed layer 100m deep would approach equilibrium (degas) in about a month.
Even a 1000-m thick winter mixed layer would degas about 30% during a three-month winter window. The ventilation time of subsurface waters depends on the depth and the fluid trajectories in the water (Luyten et al., 1983), but 50 years is enough time that a significant fraction of the methane dissolving
from bubbles might reach the atmosphere before it is oxidized.”
Large emissions of methane has been documented along the Siberian coastline. Coastal melting has resulted in 2500% supersaturation concentrations of methane relative to the atmosphere in Siberian shelf waters (Shakhova et al., 2005). With a supersaturated solution the rising bubbles cannot dissolve and will proceed unimpeded to the atmosphere.
I was astonished to note that ocean surface temperatures of over 60 degrees were being recorded in small areas of the Arctic and Alaskan Pacific. This is likely to substantially add heat to subsurface methane deposits. A massive fraction of the Arctic land mass is covered by small and medium sized lakes. It is likely that the surface water on those lakes will have similar increases in maximum and average temperatures. Arctic lakes typically never freeze at the bottom in the winter. The implication is that there is an area, called a talik, that remains unfrozen and penetrates deep into the permafrost.
An article on these taliks:
talk about how a significant minority of them already reach down below the zone of methane hydrate stability. Some of them are projected to have an unfrozen talik extending down 300 meters. What this means is that there is a mechanism that allows for easy release of methane from below the lake and perhaps easier movement of the increased surface heat to deep permafrost deposits. Obviously the rising methane bubbles will pull some of the water with them. To some extent the resulting partial reduction in fluid pressure will pull fluid from any source that can provide it. Almost certainly that will include some of the warm surface water. This will result in much more than the possible release of preexisting methane, There is massive amounts of organic carbon that has not yet been converted to methane combined with bacteria that likes to eat it and produce methane. In another study it was noted that the thawed area under one lake extended 8 feet in a single year.
Subsurface soundings very often document frozen methane hydrates by the methane bubbles below the methane stability zone. The bubbles cannot move upward because methane hydrate is cemented in all of the available pore space. What will happen when the majority of the taliks penetrate the stability zone instead of only 25% of them or less. The methane pressure near the talik is much reduced when the bubbles below and near the talik are released. The remaining bubbles can in principle move laterally because the pore spaces are not clogged with hydrate. In addition the oxidation of carbon by methanogenic bacteria will release some heat in the same way that oxidizing carbon by burning it releases heat. Obviously this mechanism will create heat at a slower rate than burning but we know that land dumps that are producing methane can become extremely hot because of this mechanism. I have seen no studies documenting this possibility in the Arctic but it is a very well understood phenomenon in domestic dump sites.
It is common knowledge in the waste industry that 5% of landfill fires are caused by spontaneous combustion due to bacteria digesting material. This can be substantially enhanced by any mechanism that adds oxygen to the mixture. However, even more heat is often generated without oxygen. In terms of the magnitude of the heat consider this article:
“The maximum reported temperatures generally varied from approximately 40 to 65°C and were observed within the middle one-third depth to over one-half depth of landfills with total waste heights
of approximately 20 to 60 m. An exception was reported by Koerner #2001# where low temperatures between 10 and 20°C were measured for wastes with a maximum height of nearly 50 m in the long term #more than 9.5 years#. Temperatures up to approximately 30 to over 50°C were reported near or at the base of landfills #Dach and Jager 1995; Rowe 1998; Gartung et al. 1999; Yoshida and Rowe 2003#,”
Even modest generation of heat in permafrost or organic material near methane hydrates by this mechanism can vastly enhance a tipping point process that continues to a runaway human disaster.
The methane hydrates are a major risk because they are known to very unstable if the specific conditions required to maintain them are changed. However, the existing organic material in permafrost is also a risk. Quoting from the Archer article:
“Peat deposits are a substantial reservoir of carbon, are estimated to be 350–450 Gton C (Stockstad, 2004). With a thaw will come accelerated decomposition of this organic matter, increasing the flux of CO2 and CH4 (Liblik et al., 1997; Rivkina et al., 2000, 2004). Soil that has been frozen for thousands of years still contains viable populations of methanotrophic bacteria (Rivkina et al., 2004). The flux of methane from peat soils to the atmosphere also depends on the location of the water table, which controls the thickness of the oxic zone (Bubier et al., 1995, 2005; Liblik et al., 1997). If 20% of the peat reservoir converted to methane, released over 100 years, this would release 0.7 Gton C per year, doubling the atmospheric methane concentration.”
OH ions are needed to oxidize methane. High levels of methane will reduce the OH ions in the atmosphere and extend the half life of methane. This can substantially expand its warming impact. A formal model calculating this impact started with a base assumption of a 9.1 year half life now. With 4 times the methane it expands to 14.7 years. A seven fold increase would produce a 18 year life.
I saw one suggestion that a catastrophic methane release could produce a 40 year atmospheric life for released methane. Given that we have only 3GT of methane in the atmosphere now and there are possibly thousands of gigatons in various deposits, this big a release is certainly conceivable.
The study referenced in the last link above ended with:
“There is a possibility that the Arctic temperature increases could be followed by extensive permafrost
thawing, with enhanced CH4 emission from thermokarst lakes [Walter et al. , 2006], with later release of CH4 from gas hydrates that would eventually be affected by warming temperatures. Considering the large, nonlinear atmospheric chemistry feedbacks discussed here, future CH4 emissions from permafrost deposits could be a larger concern for climate warming than previously thought.”
The majority of mainstream climate scientists use this very careful language. However, they also are documenting categories of risk that are very inconsistent with the seemingly unconcerned IPCC summary judgment. The known science suggests that we at minimum need a massive investment in the science so that we can have confidence concerning what is happening now and make reliable predictions on the future. A 6 degree centigrade increase in planetary temperature will make most of the world profoundly miserable for humanity. This will not cause humanity to become extinct. However, there will be a massive reduction in human population combined with destabilizing war as people desperately fight for the resources required to survive.
We have no proof that we will have any catastrophic methane release from the Arctic. However, virtually every aspect of the current system has elements that are only partially understood and can vastly expand the release of methane beyond current assumptions. We need to do the research to either verify that the carbon and methane will remain stable or give us an understanding about the magnitude of our climate risk.