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.
//end quote//
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:
Quote:
“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.
