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Amplifying
Feedbacks: US Navy Climate Model Shows Zero Sea Ice By Summer 2016,
Confirms Stark Predictions by Wadhams, Duarte
16
December, 2013
Ever
since 1995 and especially since 2007 Arctic sea ice area, volume and
extent have been in rapid free-fall. By 2012 both sea ice area and
extent had suffered losses greater than 55% when compared to end
summer measures in 1979. Sea ice volume, meanwhile had shown a
stunning loss of nearly 80% from 1979 volume observations. This
staggering trend of losses means that any melt year comparable to
2007, 2010 (volume) or 2012 would result in the total or near total
loss of all sea ice within the Arctic by end of summer.
The
summer of 2013 was exceptional in that it was the first year that
statistical averages indicated a potential for total summer sea ice
loss. The risk at the time was considered to be low, only 10%. But
the figure was historic in that, never before, had a statistical risk
of total sea ice loss been identified. Following more typical trends,
the 2013 melt season showed a bounce-back from 2012′s record melt
year with levels roughly correlating with those seen in 2009. That
said, even 2013′s pseudo-recovery did little to disturb an
extraordinarily powerful melt trend:
(Sea
Ice Volume Measurements For All Months as Observed By PIOMAS With
Exponential Trend. Image source: Wipneus.
Note that the exponential trend shows monthly volume measures for
July, August, September and October reach zero sea ice volume all
before 2019.)
Taken
into context, the 2013 melt season was little more than a
counter-trend year in a period of ongoing and apparently inexorable
decline. In context to these massive losses, the heat forcing in the
Arctic continues to grow with most regions of the showing at least a
doubled rate of temperature increase when compared to the global
norm. Total temperature change in the Arctic is now about 2 degrees
Celsius hotter than the 1950 to 1980 global average. A recent study
of the regions around Baffin Island showed temperatures are now
hotter than at any time within at least the last 44,000 years and
probably the last 120,000 years. And with temperatures rising by
about .4 degrees Celsius each decade, the Arctic continues to rapidly
transition toward ever more hot and unfamiliar territory.
A
High Resolution Climate Model For An Arctic in Rapid Transition
These
rapid and massive changes appear to have left conventional global
climate models (GCMs) in the dust. Earlier global climate model runs
of the Arctic assumed slow responses to temperature increases by the
world’s ice sheets resulting in predictions for ice free Arctic
Ocean conditions at much higher temperatures than those currently
being observed. The result of these assumptions that Arctic sea ice
generated high inertia and was more resilient to human caused climate
change were predictions for ice free Arctic summers to hold off until
at least 2100.
But,
as we have seen in the above analysis, recent events have put the
possibility for ice free Arctic conditions on a much shorter
time-scale. And, until recently, only statistical analysis,
exponential trends fitting, and direct observation were able to
provide any direct guide that more closely fit the stark and ongoing
changes in the Arctic. In a world where simulative models seemed to
take precedence over even observed reality, the dearth of models
describing what all could plainly see was a catastrophic and rapid
melt trend cast doubt on the all-too-stark observations.
Now,
a new tool to place these much more rapid than expected melt
conditions into context has emerged. The high resolution Regional
Arctic Systems Model (RASM) constructed by US Navy Scientist
Professor Wieslaw Maslowski shows the potential for the Arctic to be
ice free come 2016 +/- 3 years. This new model takes into account a
more detailed summary of Arctic conditions including a more highly
resolved interpretation of the impacts of warming-driven changes to:
“…
sea ice deformation,
ocean eddies, and associated ice-ocean boundary layer mixing,
multiphase clouds as well as land-atmosphere-ice-ocean interactions.”
Dr.
Maslowski notes that while no climate model simulation is perfectly
accurate, the RASM simulation is likely much closer to what is
actually happening in the Arctic environment. Maslowski notes:
“Given
the estimated trend and the volume estimate for October–November of
2007 at less than 9,000 km3, one can project that at this rate it
would take only 9 more years or until 2016 ± 3 years to reach a
nearly ice-free Arctic Ocean in summer. Regardless of high
uncertainty associated with such an estimate, it does provide a lower
bound of the time range for projections of seasonal sea ice cover.”
Confirmation
of the Most Pessimistic Predictions
Dr.
Maslowki’s RASM model runs provide single source confirmation for
some of the most pessimistic predictions by Arctic sea ice experts.
Dr. Peter Wadhams, a world renown sea ice expert who has spent about
30 years monitoring the state of sea ice aboard British Navy
submarines has projected that the Arctic could reach an ice-free
state by the end of summer during 2015 or 2016.
Another
climate expert, Dr. Carlos Duarte, head of the Ocean Institute at the
University of Australia, has projected that the Arctic will reach an
ice free state by 2015.
More
moderate projections place total sea ice loss during summer at
between 2025 and 2040. Meanwhile, global climate models (GCMs)
continue to lag real time observation, projections by noted experts,
and the projections of high resolution regional models like
Maslowki’s RASM.
Loss
of Summer Sea Ice to Unleash Amplifying Feedbacks
Because
it covers such a large stretch of ocean with a white, reflective
surface, sea ice is a primary governor of Arctic and global weather.
It keeps the Arctic cool by insulating millions of square kilometers
of dark Arctic Ocean waters from the near constant radiation of the
polar summer sun.
As
the sea ice retreats, more of this dark water becomes exposed to the
sun’s rays. Because the ocean surface is dark, it traps most of
this light. The result is far greater warming of the Arctic during
the summer time.
The
loss of sea ice and related ocean warming has a number of knock-on
effects. The first is that increasing ocean heat delivers far more
energy to the sea bed. In the case of the East Siberian Arctic Shelf,
the warming shallow sea is one filled with carbon deposits from a
massive expanse of submerged tundra. An estimated 1500 gigatons of
methane lay sequestered in thawing permafrost beneath this rapidly
warming sea. According to Wadhams, loss of sea ice can add up to 7
degrees Celsius of additional warming to this vulnerable sea bed.
Current
estimates provided by Dr. Natalia Shakhova show that around 17
megatons of methane are being released from the ESAS each year. This
emission is more than twice that of the entire global ocean system
and accounts for about 2.8 percent of the current global methane
emission. Given the massive volume of methane stored in the ESAS and
the rapid pace of sea ice loss and related ocean warming, this region
of the world is more than capable of providing significant additional
volumes of this potent greenhouse gas.
(A frothy mixture of methane and sea ice near the East Siberian Arctic Shelf. Image source: Igor Semiletov, The University of Alaska)
Meanwhile,
ship based observations show that methane levels at the surface of
ESAS waters are a stunning 3800 ppb, about twice the global average:
“Ship-based
observations show that methane concentrations in the air above the
East Siberian Sea Shelf are nearly twice as high as the global
average… Layers of sediment below the permafrost slowly emit
methane gas, and this gas has been trapped for millennia beneath the
permafrost. As sea levels rose at the end of the ice age, the shelf
was once again covered by relatively warm ocean water, thawing the
permafrost and releasing the trapped methane… In the short-term…
methane has a global warming potential 86 times that of carbon
dioxide. (NSIDC)”
More
rapid Arctic Ocean warming during summer times also results in more
rapid warming of nearby land masses. And recent years have seen a
number of extraordinary Arctic heatwaves driving 80+ degree
temperatures all the way to the shores of the Arctic Ocean. Rapid
warming of this region also results in a rapid thaw of massive
volumes of permafrost. The permafrost stores organic material that
breaks down into both CO2 and methane, providing additional emissions
that enhance an already very rapid human warming. Current emissions
from the Arctic tundra system are estimated to be around 17 megatons
of methane and hundreds of megatons of CO2. Like the emissions coming
from the ESAS, these emissions provide a significant added
contributor to the human GHG forcing and will likely continue to
provide increasing emissions as the sea ice retreats further.
In
addition to the combined amplifying feedback of loss of sea ice
albedo and amplifying greenhouse gas emissions from the Arctic, sea
ice erosion has now also been shown to have profound effects on the
circumpolar Jet Stream. Research by Dr. Jennifer Francis, Dr. Quihang
Tang, a number of other scientists, and confirming analysis by Dr.
Jeff Masters, has noted a weakening in the Jet Stream caused by a
lowering of the temperature differential between the lower latitudes
and the poles. The Jet is driven by such high temperature extremes
between north and south. But as the higher latitudes warm faster than
the temperate zones this temperature differential drops and the Jet
Stream weakens. The end result is higher amplitude Jet Stream waves
that tend to get stuck, resulting in more persistent, extreme
weather. Dr Quihang, in a recent paper, notes:
“As
the high latitudes warm faster than the mid-latitudes because of
amplifying effects of melting ice, the west-to-east jet-stream wind
is weakened. Consequently, the atmospheric circulation change tends
to favour more persistent weather systems and a higher likelihood of
summer weather extremes.”
The
end result of these alterations brought on by a very rapid loss of
Arctic sea ice are chaotic changes to the Arctic Ocean and
surrounding lands along with a severe disruption to Northern
Hemisphere weather patterns. These changes also combine in a
self-reinforcing pattern to further amplify the pace of human caused
warming both in the Arctic and around the globe. And should the
summer Arctic sea ice completely melt in the time-frame of now to
2019 as Maslowski, Wadhams and Duarte project, then the already stark
changes we are seeing will become much more extreme and pronounced.
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