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Arctic
Sea Ice Loss Goes Vertical: Area the Size of Nevada Gone in One Day
3
May, 2014
The
white, reflective barrier protecting our northern polar region from
the heat-amplifying effects of human-caused warming took a severe
blow today.
The National Snow and Ice Data Center’s sea ice area
measure essentially fell off a cliff as values plummeted by more than
286,000 square kilometers. That’s an area of ice the size of Nevada
lost in a single 24 hour period. A state-sized region flipping from
white, reflective, cooling ice, to dark, heat-absorptive water.
(Most recent day’s sea ice area measure shows vertical drop for the most recent 24 hour period. Data source: Cryosphere Today/NSIDC. Image source: Pogoda i Klimat.)
Overall,
the sprawl of sea ice fell to 9,984,000 square kilometers or a
negative 907,000 square kilometer anomaly vs the already low 1979 to
2008 mean. The fall was rapid enough to bring sea ice area to within
striking distance of new record lows for the date. Should the
nose-dive continue for just one more day, the measure’s lower range
will be shattered.
Arctic Still Warm as Extra Heat Goes to Work on Ice
Since
May, weather conditions in the Arctic above the 66.5 degrees north
Latitude line have remained somewhat warmer than usual. GFS averages
have ranged from +1.5 to -0.3 C when compared to the, already warm,
1979 to 2000 average. And, in general, values have typically hovered
in the +0.5 C range for the entire Arctic.
This
temperature anomaly range is, however, a major fall from the extreme
polar amplification we saw this winter on the order of +4 to +6 C
above ‘normal’ temperatures during the months of January and
February of 2014. It is the same relative winter-to-summer draw-down
in anomalies we would expect come summer as the heat overburden goes
to work doing the physical heavy lifting of ice melt rather than
simply warming the air. In essence, as atmospheric and ocean
temperatures approach the 28 F melt-freeze line of sea ice, energy,
instead, is dumped more and more into ice melt. So though Summer is
still quite a bit warmer than Winter in the Arctic, the pace of
atmospheric warming in the winter is much greater so long as
temperatures remain below ice-melt thresholds.
Heat
Delivery Mechanisms: How Polar Amplification Melts Sea Ice
Extra
dangerous and amplifying Arctic heat comes from many sources. Not
only is the atmosphere over the Arctic more heavily burdened with
heat-capturing gasses than the rest of the planet (currently at about
405.5 ppm CO2 and 1910 ppb methane as measured at NOAA’s Barrow
Alaska station), high amplitude jet stream waves continue to deliver
heat in the form of southerly warm wind invasions even as the ocean
upon which the thinning ice rests draws ever more energy from an
immense volume of warming water. Expanding holes in the ice, a
darker, greener, Arctic environment, a rain of soot from massive
wildfires burning at the Arctic’s gates — all contribute to
overall warming in the Arctic system.
How
this heat is delivered to the sea ice can take many forms. The first,
and most obvious, is through direct solar heating of the ice itself.
Such insolation heating requires both clear skies and warm air
temperatures for greatest impact. In these ideal conditions, melt
ponds can proliferate, greatly reducing sea ice albedo and further
weakening ice for large melts later in the season. And recent studies
suggest that widespread melt pond formation played a key role in both
of the record melt seasons of 2007 and 2012.
(Thin ice over Hudson Bay, Canada on June 2 takes on the characteristic blue tint indicative of melt pond formation. During late spring of 2014, melt pond formation was relegated to the ice edge, primarily due to widespread cloud formation over the Arctic Ocean. Image source: LANCE MODIS.)
But
for 2014, melt pond formation has been relegated to the ice edge
boundary along the fast ice near Russia, in regions of the Canadian
Arctic Archipelago, and in Hudson Bay. Large areas of cloud cover
have persisted throughout the Arctic preventing a much more
widespread occurrence of melt ponds. This high degree of cloudiness
is likely due to the changing Arctic itself where increasing
encounters between hot and cold are veritable cloud and mist
generating machines. Such changes bear out in paleoclimate
observations where proxy values show a more ice free Arctic is a much
cloudier Arctic.
So
if clouds interrupt solar insolation in a melting Arctic, then what
other mechanisms go to work to deliver heat to the ice?
Weather
Systems, Warming Lands and Waters
‘Fate,’
as the saying goes, ‘is not without its sense of irony.’ For
water in all forms, including the low-lying clouds which are fogs and
mists, is likely to play an ever-increasing role in Arctic melt.
These emerging heat delivery mechanisms can simply be summed up as
follows: warm wet winds, warm water upwelling, and warm rivers.
Warm
Wet Winds blow
from south to north and increasingly invade the Arctic as tundra
melts and sea ice retreats. As summer temperatures at the Arctic
boundary increase due to human forcings and related amplifying
feedbacks, these warm, southerly gusts bear with them an
ever-increasing moisture content. And since water has 4 times the
heat capacity of air, winds laden with higher volumes of moisture
carry much more heat to melt ice than the drier, colder winds of
yore. When such winds contact the ice, a form of condensation mist is
wrung out of the air due to temperature differential. The mist
directly contacts the ice and delivers its x4 heat capacity to the
ice surface. It’s a phenomena that many coastal residents in the
northeastern US are well familiar with — something they call
snow-eating fog.
During
late spring of 2014, warm, wet winds were particularly prevalent in
the region of the Bering and Chukchi Seas. These winds weren’t much
warmer than sea ice freezing temperatures — ranging from 28 to 40
degrees F. But they picked up moisture in a large south to north
synoptic pattern, dredging up heat and water from the temperate
Pacific to dump it on the Arctic sea ice. The result was great gusts
of mists and fogs eating away at the ice edge week-after-week.
In
the above satellite image sequence (LANCE
MODIS),
we can see the drastic effects of prevalent warm winds. The top image
is from April 25 of 2014, the bottom from June 2nd. In the top frame
we can see the beginnings of mist and cloud formation at the ice edge
along the path of persistent south to north wind flow. By June 2nd,
this warm wind pattern has melted most of the Bering and Chukchi sea
ice even as it intensified to a misty, cloudy maelstrom chewing away
at the ice edge.
A
more intense kind of a warm wind forcing can come in the form of a
warm storm. These storms typically emerge from the south carrying
with them a high degree of heat and moisture. A combination of rain,
strong winds and increased wave action over sea ice can have a severe
effect during a warm storm as was seen during the Great Arctic
Cyclone of 2012. Such storms are likely to become more prevalent as
the Arctic continues to heat up. And these systems can also generate
a kind of warm water upwelling that eats away at the ice from below.
Warm
Water Upwelling is
an especially powerful force to melt ice that sits on a warming
ocean, particularly when the ice is as thin, broken and mobile as we
see in the Arctic today.
Impacts
from warming and upwelling deep ocean waters have been both
extraordinary and increasingly visible to major glacial systems in
Greenland and West Antarctica where numerous ice sheets have begun an
irreversible plunge toward the oceans.
In
the Arctic, heat typically pools in deeper layers and at the
near-shore below-surface boundary along the continental shelf. The
ice rests in a zone of colder water at the surface. Atmospheric
patterns such as persistent and strong high and low pressure systems
can occasionally tap this deeper water heat through a mechanism known
as Ekman pumping.
The
way this works is that a large-scale swirl of air creates a kind of
suction effect on the sea surface. In cyclonic storms, Ekman pumping
causes upwelling to occur at the center of the storm and down-welling
to occur at the edges. In high pressure systems, upwelling occurs
along the edges while down-welling occurs at the center.
(Illustration of Ekman transport is cyclonic [storm] and anticyclonic [high pressure] systems. Image source: MIT.)
The
effect this has on sea ice is that storms will tend to spread the ice
out and thin it at their centers while high pressure systems will
tend to pull the ice edge in and concentrate the ice. In addition,
the upwelling at the edges of the anticyclone can add melt stress,
especially in more shallow coastal basins, even as melt stress is
added along storm paths in which warmer waters may have ventured
closer to the ice bottom.
During
the last week, a persistent high pressure system formed over the
Beaufort Sea. It sat opposite a set of cyclones that formed near the
Kara. The anticyclonic pattern of the high drew in ice from land-fast
moorings in the East Siberian Sea even as warm upwelling and loss of
albedo generated warmer surface temperatures in an expanding polynya
zone — pumping out a burst of ice-eating mists. The anticyclone
expanded into the Laptev where a similar edge draw and surface
warming effect was visible even as the wind patterns between
anticyclone and cyclone converged to amplify the northward retreat of
ice.
In the top LANCE MODIS image frame we see East Siberian and Laptev seas already suffering ice loss and break-up due to a series of warm wind outbursts from the Asian continent on May 15 of this spring. In the bottom frame, we see today’s sea ice coverage dramatically reduced after a week of extreme ice damage due to anticyclonic recession and related edge upwelling.
Warm
Rivers also
typically provide a strong pulse of heat to the Arctic through spring
and into summer. As the Arctic lands thaw and the large continents
warm, water flows from thawed rivers increase. In recent years, Jet
Stream wave amplification has combined with warming temperatures in
the region of 55 to 75 North Latitude to increase storminess and
rainfall intensity. As a result, higher volumes of warmed waters
flood north into what was once the ice sanctuary of the Arctic Basin.
The pulse of water is generally enough to disintegrate land-fast ice
and speed the ice melt further offshore.
Though
large warm water pulses are not yet visible, regions to watch for
2014 will be the Mackenzie Delta and the mouths of the Kolyma, Lena,
Yenisey, and Ob rivers. Major rainfall events in Siberia have been
ongoing over the past week and will likely generate increased volumes
of warm water flow for the Lena and Yenisey rivers particularly.
It
is also worth noting that much warmer than average conditions have
spread over the Mackenzie and Ob river basins.
Forecast
Shows High Rate of Melt Likely
Today’s
weather shows a continued building of the high pressure ridge over
the Beaufort with GFS model forecasts predicting the ridge will
remain in place over at least the next seven days. Persistence of
this ridge pattern will continue to draw the ice in from the East
Siberian and Laptev Seas even as warm winds over the Chukchi are
reinforced. Sea ice totals may further be drawn down from rapid melt
proceeding in both Hudson and Baffin Bay. Melt in these areas has
lagged behind the larger Arctic somewhat, so current near record low
totals are yet higher than they would otherwise be.
(107 hour GFS Model temperature forecast. Image source: University of Maine.)
Meanwhile,
model runs show the Arctic steadily devolving into a kind of melt
soup where atmospheric temperatures push into an above-freezing range
for sea ice over the majority of the Arctic even as shore regions of
Yakutia and the Mackenzie Delta are forecast to see temperatures in
the mid 60s and 70s. These readings are in the daily range of +0.3 to
+1.9 C above the 1979 to 2000 average for the entire area above the
Arctic Circle and are predicted to hit local spikes from +4 to +18 C.
It
should go without saying that a 70 degree reading in early June on
the shores of the East Siberian Sea in the high Arctic is a clear
sign of human-caused climate change gone nuts. And we are likely to
see these and higher readings as spring proceeds into summer.
So
though general cloudiness over the Arctic may continue to suppress
melt pond formation, there likely remains enough heat baked-in to
keep testing new record lows for sea ice. Even under cloud cover,
dangers to the sea ice abound in the form of warm winds, warm storms,
warm water upwelling, and a growing heat pulse from warming Arctic
rivers. Amplifying heat and a growing number of ways in which that
heat can be transferred to ice creates an ever-expanding risk for ice
free conditions. Under such a regime, unexpected and extreme events
are increasingly likely.
Links:
Arctic sea ice in steep decline
3
June, 2013
Arctic
sea ice area is in steep decline. The yellow line on the image below
shows the sea ice area for 2014 up to June 1st, showing an
almost vertical fall over the past few days.
 |
| [ click on image to enlarge ] |
The
Naval Research Laboratory image below compares the May 14, 2014, sea
ice concentration (left) with the sea ice concentration forecast for
June 10, 2014 (run on June 2, 2014, on the right).
 |
| [ click on image to enlarge ] |
The
NOAA image below shows sea surface temperature anomalies on June 3rd,
2014.
The
NOAA image shows the huge sea surface temperature anomalies all over
the Northern Hemisphere on June 3rd, 2014. Large areas with sea
surface temperature anomalies up to 8 degrees Celsius and higher show
up in and around the Arctic Ocean
 |
| [ click on image to enlarge ] |
The
image below shows sea surface temperature anomalies up to 1.5 degrees
Celsius over the May-June 2014 period, with global average anomalies
that hover just above 1 degree Celsius.
Above
sea surface anomalies are very high, much higher than historic
annual temperature anomalies over land and oceans, as shown on the
image below for comparison.
In
conclusion, the situation spells bad news for the sea ice, also given
the prospect of an El
Niño
event projected to occur later this year.
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