US
Navy predicts summer ice free Arctic by 2016
Nafeez
Ahmed
Greenpeace
icebreaking ship, Arctic Sunrise, among broken floes of Arctic sea
ice, photographed from the air. This image was taken in the Fram
Strait, in the month that the sea ice coverage receded to the second
lowest extent since records began. Photograph: Nick Cobbing
9
December, 2013
An
ongoing US Department of Energy-backed
research project led by a US Navy scientist predicts that the Arctic
could lose its summer sea ice cover as early as 2016 - 84 years ahead
of conventional model projections.
The
project, based out of the US
Naval Postgraduate School's
Department of Oceanography, uses complex modelling techniques that
make its projections more accurate than others.
A
paper
by principal investigator Professor Wieslaw Maslowski in the Annual
Review of Earth and Planetary Sciences sets out some of the findings
so far of the research project:
"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."
The
paper is highly critical of global climate models (GCM) and even the
majority of regional models, noting that "many Arctic climatic
processes that are omitted from, or poorly represented in, most
current-generation GCMs" which "do not account for
important feedbacks among various system components." There is
therefore "a great need for improved understanding and model
representation of physical processes and interactions specific to
polar
regions
that currently might not be fully accounted for or are missing in
GCMs."
According
to the US
Department of Energy
describing the project's development of the Regional Arctic System
Model (RASM):
"Given
that the Arctic is warming faster than the rest of the globe,
understanding the processes and feedbacks of this polar amplification
is a top priority. In addition, Arctic glaciers and the Greenland Ice
Sheet are expected to change significantly and contribute to sea
level rise in the coming decades."
Such
Arctic changes "could have significant ramifications for global
sea level, the ocean thermohaline circulation and heat budget,
ecosystems, native communities, natural
resource exploration,
and commercial transportation."
The
regional focus of RASM permits "significantly higher spatial
resolution" to represent and evaluate the interaction of
"important fine-scale Arctic processes and feedbacks", such
as:
"...
sea ice deformation, ocean eddies, and associated ice-ocean boundary
layer mixing, multiphase clouds as well as land-atmosphere-ice-ocean
interactions."
The
role of the Department of Energy in backing the research is not
surprising considering that President Obama's national
Arctic strategy
launched in May is focused on protecting commercial and corporate
opportunities related to control of the region's vast untapped oil,
gas and mineral resources.
The
model coheres with the predictions of several other Arctic
specialists - namely Prof Peter
Wadhams,
head of polar ocean physics at Cambridge University and Prof Carlos
Duarte,
director of the Ocean Institute at the University of Western
Australia - who see the disappearance of the Arctic sea ice in the
summer of 2015 as likely.
Prof
Wadhams is co-author of the
controversial Nature paper
which calculated the potential economic costs of climate
change
based on a scenario of 50 Gigatonnes (Gt) of methane being released
this century from melting permafrost at the East Siberia Arctic Shelf
(ESAS), a vast region of shallow-water covered continental crust. The
scenario was first postulated by Natalia Shakhova and Igor Semiletov
of the International Arctic Research Centre at the University of
Alaska, Fairbanks.
In
2010, Shakhova's team published results showing that 7 teragrammes of
methane was bubbling to the surface annually in the ESAS. Last month,
she released a new paper
in Nature Geoscience
updating these findings on the basis of more
rigorous measurements
using an unmanned underwater vehicle with advanced sonar capability.
She found that annual bottom water temperatures have increased over
the last 14 years, correlating with a release of about 17 teragrammes
of methane a year, accentuated by storms. This conservative estimate
is more than double the earlier assessment.
However,
the source of these methane emissions remains a matter of dispute, as
other scientists investigating the phenomenon point out that while
large deposits of methane hydrates could be breaking up, the other
possibility is a slow leak of methane that has already gone on for
hundreds of years. Christian
Berndt,
of the GEOMAR/Helmholz Centre for Ocean Research, has speculated that
both phenomena could be going on at once, but he admits, "We
have no proof."
Despite
their latest study uncovering higher levels of methane than
previously recognised, Shakhova has also distanced herself from the
'methane bomb' scenario she had once previously posited, noting a
lack of direct evidence for the scenario.
"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."
Most
scientists agree that more research is needed to determine the source
and nature of these methane emissions.
But
scientists also largely agree that an ice free Arctic in the summer
could have serious consequences for the global climate. Some research
has pointed out a link between the warming Arctic and changes in the
jet stream, contributing to unprecedented weather extremes over the
last few years. These extreme events in turn have dramatically
impacted crop production in key food basket regions.
A landmark
new study
in Nature Climate Change
finds the melting of the sea ice over the last 30 years at a rate of
8% per decade is directly linked to extreme summer weather in the US
and elsewhere in the form of droughts and heatwaves. Lead study
author Quihang Tang at the Institute of Geographic Sciences and
Natural Resources Research in Beijing said:
"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
new study supplements earlier
research
published in Geophysical Research Letters demonstrating a link
between Arctic sea ice loss and extreme weather particularly in both
the summer and winter, including prolongation of "drought,
flooding, cold spells, and heat waves."
Last
year Prof Duarte was lead author of a paper in the Royal Swedish
Academy of Science's journal AMBIO warning that the Arctic was at
risk of passing critical "tipping
points"
that could lead to a cascading "domino effect once the summer
sea ice is lost." Prof Duarte said at the time:
"If
set in motion, they can generate profound climate change which places
the Arctic not at the periphery but at the core of the Earth system.
There is evidence that these forces are starting to be set in motion.
This has major consequences for the future of human kind as climate
change progresses."
Dr
Nafeez Ahmed
is executive director of the Institute
for Policy Research & Development
and author of A
User's Guide to the Crisis of Civilisation: And How to Save It
among other books. Follow him on Twitter @nafeezahmed
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