Not the full story, but...Thank goodness for some context behind the rescue of the Akademik Shakalskiy and why it should become trapped in summer ice. All we get here in New Zealand is a story of a rescue and nothing of the story, either of why they are there or of the climate science.
The
Paradox of Antarctic Sea Ice 2: Research vessel trapped by summer sea
ice
31
December, 2013
I
came across an article lambasting the Australian Antarctic Expedition
scientists on board the MV Akademik Shokalskiy trapped by fast ice
since Christmas Eve in the Commonwealth Bay region of Antarctica.
Climate scientists and tourists are on board the vessel on the Spirit
of Mawson voyage,
retracing Sir Douglas Mawson's Antarctic expedition.
The
ship found itself locked in thick ice after experiencing blizzard
conditions which moved and piled up ice flows.
Ships
can get trapped by pack ice in polar waters very quickly during
blizzards. Pack ice moves around with wind conditions, and it is not
uncommon for ships to become temporarily locked in the ice even
during peak summer conditions in Antarctica.
But
Daniel Greenfield seems
to think
a ship trapped in Antarctic summer sea ice is a negation of global
warming and the science involved in climate change. He is not
alone...
. @tan123 @profchristurney Yes because the ice comes from the berg B09B that broke off Antarctica 3 years ago.
— Climate Scientists (@ClimateSystem) December 30, 2013
His
view probably had it's origins in the climate sceptical website Watts
Up with That
where Anthony Watts wrote: So
much sea ice in Antarctica that a research vessel gets stuck, in
summer!.
But
Mr Greenfield, or Anthony Watts for that matter, made little attempt
to explain the complex science involved with understanding Antarctic
sea ice.
Arctic and Antarctica have different geographies
Unlike
the Arctic where there is a marked long term decline in extent and
volume of sea ice, the trend for sea ice in Antarctica shows a slow
growth in extent setting new maximum extent records in recent years.
The long term trend (1979-2008) shows an increase of 0.9% per decade
in Antarctic sea-ice, while Arctic sea-ice shows a decrease of 4.1%
per decade (NSIDC).
Some
commentators estimate Arctic summer sea ice may vanish in the next
few years. Nafeez Ahmed reports the US
Navy predicts summer ice free Arctic by 2016.
Despite slightly higher summer sea ice this year, Sea
Ice Volume is Not Recovering.
Winter recovery of Arctic sea ice stalls - 25Dec2013 sea ice extent 3rd lowest on record
The
different geographies of the Arctic and Antarctic - one surrounded by
land masses, the other by ocean - mean that different wind, ocean
currents, and heat transfer processes occur.
Unravelling
the puzzle of sea ice in Antarctica
In
the early 1990s Syukuro
Manabe
and colleagues from Princeton University predicted increasing
antarctic ice due to increased precipitation (snow) being compacted
to ice, using early Global climate models. Although they articulated
that there were different processes at work in the Arctic and
Antarctic, they found the results indicating Antarctic sea ice
increase puzzling.
Oceanographic
data also find that the waters in the Southern Ocean are warming. The
waters of the Southern Ocean's Antarctic Circumpolar Current have
warmed more rapidly than the global ocean as a whole. From 1960 to
2000, water temperature increased by 0.068°C per decade at depths
between 300 and 1000 metres. This warming trend has increased to
0.098°C per decade since the 1980s (Boning
2008)
Later
(Markus
and Cavalieri 2006)
postulated that "Snow depth on sea ice plays a critical role in
the heat exchange between ocean and atmosphere because of its thermal
insulation property....The results show an overall increase in snow
depth for each of the five Antarctic sectors and the region as a
whole, but only the Indian Ocean sector and the entire Southern Ocean
show a statistically significant increase."
In
this 2005 youtube
video Thorsten Markus from NASA GISS describes how precipitation
increases Antarctic sea ice:
In
November 2012 I reported on the puzzle of Record
Antarctic Sea Ice Growth
in an article where I explained that (Holland
et al 2012)
argued that atmospheric variability in the form of local winds was
pushing the ice northwards creating space for new sea ice to form.
In
my blog from April 2013 on the Antarctic
Paradox: ocean warming melting ice shelves causing sea ice expansion
I explain the paper by (Bintanja
et al 2013)
in which they argue that the freshly melted cool and fresh water from
the Antarctic land mass forms a surface layer protecting sea ice and
helping it's expansion insulating it from the deeper warm salty
currents.
Peter
Sinclair from the Yale Climate Forum produced this video in November
2012 which also explains Antarctic Sea ice growth:
Antarctic
westerlies wind vortex growing stronger, increasing sea-ice?
A
paper this year (Zhang
2013)
by Jinlun Zhang, from the University of Washington, argues that about
80 percent of the growth can be explained by changes in the
prevailing winds around the frozen continent - the
westerlies;
the remaining 20 percent, he suspects, might be the result of changes
in ocean circulation.
"The
overwhelming evidence is that the Southern Ocean is warming,"
said author Jinlun Zhang, an oceanographer at the UW Applied Physics
Laboratory. "Why would sea ice be increasing? Although the rate
of increase is small, it is a puzzle to scientists."
Zhang's
modelling work has involved studying of the polar vortex, the winds
that swirl around Antarctica and have been growing stronger over the
last three decades. The Westerly winds are stronger and have more
convergence, shoving the sea ice together to cause ridging. Stronger
winds also drive ice faster, which leads to still more deformation
and ridging. This creates thicker, longer-lasting ice, while exposing
surrounding water and thin ice to the blistering cold winds that
cause more ice growth.
In
the modelling simulation that involved interactions between wind and
sea, thick ice increased by about 1 per cent per year from 1979 to
2010, while the amount of thin ice remained relatively constant.
"You've got more thick ice, more ridged ice, and at the same
time you will get more ice extent because the ice just survives
longer," Zhang said.
"People
have been talking about the possible link between winds and Antarctic
sea ice expansion before, but I think this is the first study that
confirms this link through a model experiment," commented Axel
Schweiger, a polar scientist at the UW Applied Physics Lab. "This
is another process by which dynamic changes in the atmosphere can
make changes in sea ice that are not necessarily expected."
Here
is Zhang's abstract for Modeling
the impact of wind intensification on Antarctic sea ice volume:
A
global sea ice-ocean model is used to examine the impact of wind
intensification on Antarctic sea ice volume. Based on the NCEP/NCAR
reanalysis data, there are increases in surface wind speed (0.13%
yr−1) and convergence (0.66% yr−1) over the ice-covered areas of
the Southern Ocean during the period 1979-2010. Driven by the
intensifying winds, the model simulates an increase in sea ice speed,
convergence, and shear deformation rate, which produces an increase
in ridge ice production in the Southern Ocean (1.1% yr−1). The
increased ridged ice production is mostly in the Weddell,
Bellingshausen, Amundsen, and Ross Seas where an increase in wind
convergence dominates. The increase in ridging production contributes
to an increase in the volume of thick ice (thickness > 2 m) in the
Southern Ocean, while the volumes of thin ice (thickness ≤ 1 m) and
medium thick ice (1 m < thickness ≤ 2 m) remain unchanged over
the period 1979-2010. The increase in thick ice leads to an increase
in ice volume in the Southern Ocean, particularly in the southern
Weddell Sea where a significant increase in ice concentration is
observed. The simulated increase in either the thick ice volume
(0.91% yr−1) or total ice volume (0.46% yr−1) is significantly
greater than other ice parameters (simulated or observed) such as ice
extent (0.14–0.21% yr−1) or ice area fraction (0.24–0.28%
yr−1), suggesting that ice volume is a potentially strong measure
of change.
I
doubt this is the final study to shed light on this puzzle of growth
in Antarctic sea ice in a warming world. More than likely it is a
combination of factors to varying degrees as articulated in the
various research listed above. The science remains complex.
The
sea ice growth trend in Antarctica is small compared with the amount
being lost in the Arctic, so that there is an overall significant
decrease in sea ice worldwide.
Zhang
anticipates that warmer temperatures will eventually resolve the
apparent contradiction.
"If
the warming continues, at some point the trend will reverse,"
Zhang said.
You
can read more on Zhang's study at Climate Central: Winds
of Change: Why Antarctic Sea Ice Is Growing
Dr
James Renwick, a climate scientist from New Zealand NIWA asks in this
April 2012 youtube
video
how much longer is this increase in sea ice going to continue? It
can't continue indefinitely...
Dr
Mike Williams, a Physical Oceanographer from New Zealand says in an
April 2012 Youtube
video
that:
"model
predictions suggest that their won't be significant changes in sea
ice until 2080. After that point it will actually start reducing
quite rapidly. That will have a profound effect on both ocean
circulation and the climate system because we won't get that deep
water formation. Without seaice there to form this big reflective
blanket, we don't have the sunlight bouncing back up into space, so
we will have oceans warming to radiate heat and heat the atmosphere
and that will modify atmospheric circulation. Essentially there is a
number of complex feedbacks which we probably don't understand nearly
well enough yet."
Akademik
Shokalskiy locked in summer ice
So
the Akademik Shokalski remains trapped since 24 December, 100
nautical miles east of French Antarctic station Dumont D'Urville and
about 1,500 nautical miles south of Tasmania. The ship is privately
chartered with 74 passengers including both scientists and tourists,
many of them Australian, and 22 Russian crew.
The
Chinese icebreaker Xue Long (Snow Dragon) has already made an attempt
to reach the ice-locked vessel, but the ice proved too thick. The
French ice breaker l'Astrolabe is also nearby. The Australian
Antarctic Division vessel Aurora Australis came within 6 nautical
miles, but has had to withdraw
to open water
due to further Blizzard conditions.
 |
If a second rescue attempt to open a lead to the Akademik Shokalski fails, the passengers can be transferred by helicopter to the Auroa Australis leaving a skeleton crew aboard the vessel for when the pack ice and leads open up later in the summer with wind changes.
Australian Greens senator elect for Victoria Janet Rice appears in this Guardian Youtube video published 30 December 2013 from on board the Akademik Shokalski. Janet has a scientific background with her honours thesis on where lows around Antarctica were born and died. She will bring to the new Senate a perceptive understanding of climate science and the need for strong climate action.
Sources:
Daniel
Greenfield, Frontpage Mag, 29 December 2013 - Global
Warming Expedition to Prove Antarctic Ice is Melting Trapped by Ice
Hannah
Hickey, University of Washington media release, 17 September 2013 -
Stronger
winds explain puzzling growth of sea ice in Antarctica
Jinlun
Zhang, Journal of Climate 2013, Modeling
the impact of wind intensification on Antarctic sea ice volume
(abstract)
doi: http://dx.doi.org/10.1175/JCLI-D-12-00139.1
Tamino,
16 March 2013 - Antarctic
Sea Ice Gain
image
- Graph of Southern hemisphere sea Ice anomaly -
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png
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