Climate and Fresh Water Change in
the Arctic Ocean
Fengyan Yang
Alison Wood
Transboundary Waters, April 5, 2012
Figure 1. The Arctic Ocean
Climate Change in the Arctic
Climate change in the arctic has the potential to cause massive effects worldwide,
including a global rise in sea level, damage to infrastructure due to thawing permafrost,
and colder winters in the northern hemisphere. Arctic climate change also threatens not
only the wildlife in the region but also the indigenous populations that rely on various
species for their cultural identities and their food source.
The average sea level worldwide has risen approximately 3 inches in the last 20 years,
and models predict that it will rise as much as 3 feet (about 90 centimeters) by the end of
the 21st century. In areas with very flat terrain, as is common in coastal plains, a sea level
rise of less than 2 feet (50 centimeters, or around 20 inches) would mean flooding up to
160 feet inland (50 meters). 1 Mapping tools used to visualize the effects of this show
that the city of New Orleans would be completely underwater if sea level were to rise by
1
http://amap.no/acia/
3.3 feet (1 meter).2 These general sea level rises are due both to the melting of land ice
and to thermal expansion because of the increased average temperature of sea water (the
melting of floating ice does not change sea level).3
Figure 2. Global Sea Level Rise
There are also dangers from the thawing of ground that has been frozen since before the
dawn of civilization. The stability of structures built in regions with permafrost is
dependent upon the stability of the ground, which will be affected by the permafrost
thawing. “Areas at high risk [for destabilization of infrastructure because of thawing
permafrost by the year 2050] encompass population centers, oil pipelines, natural gas
production facilities, and a nuclear power plant.”4 Failures of these structures could be
catastrophic, and such failures could be caused by warming in the arctic.
Figure 3. Infrastructure at Risk by 2050 due to Thawing Permafrost
2
http://climategem.geo.arizona.edu/slr/us48prvi/index.html
http://amap.no/acia/
4
http://amap.no/acia/
3
Threats come also in the form of changing temperatures in the northern hemisphere. As
seen in Europe in the winter of 2011-2012, unusually cold temperatures can be deadly:
over 200 deaths were attributed to the exceptional cold.5 The extreme cold came from
arctic air moving southwards because of pressure changes, which are caused by
increasing arctic air temperatures. As NOAA (the National Oceanographic and
Atmospheric Administration) explains, “cold air is normally trapped in the Arctic in
winter by strong Polar Vortex winds, which circle the North Pole from west to east…This
pattern broke down in December 2009, and in February 2010. North-south winds
increased, allowing cold Arctic air to spill southwards.” 6
Figure 4. Temperature Anomalies Compared to 1968-1998 Average - Warm Arctic-Cold
Continents Phenomenon
But perhaps the most widely known threat from arctic warming is to the polar bears –
they’ve become a mascot for combatting climate change because their habitat is
threatened by the loss of polar ice that accompanies arctic warming (and which is
discussed further in a few paragraphs). It is not only polar bears that are threatened, but
many species of wildlife and the indigenous people whose lives depend on those species.
“Changes in species’ ranges and availability, access to these species, a perceived
reduction in weather predictability, and travel safety in changing ice and weather
conditions present serious challenges to human health and food security, and possibly
even the survival of some cultures.”7 Entire human cultures may become extinct because
of climate change in the arctic.
5
http://www.guardian.co.uk/world/2012/feb/03/europe-cold-energy-death-toll
http://www.arctic.noaa.gov/future/warm_arctic_cold_continent.html
7
http://amap.no/acia/
6
Figure 5. How Arctic Warming May Affect Caribou
We know that climate change in the arctic is real because scientists have been able to
determine the average arctic temperature for every decade for the last 2000 years, thanks
to ice cores, tree rings, and lake sediments. For approximately 1900 years the
temperatures show a steady cooling trend, but a dramatic warming began around the year
1900. 8 In fact, air temperatures in the arctic have been increasing at approximately twice
the rate of the temperature increase of the rest of the world for the last 20 years. 9 The
2011 annual mean surface temperature anomaly, as compared to the 1951-1960 base
period, showed increases of 0-3°F (0-1.7°C) across much of the globe but increases of 37.9°F (1.7-4.4°C) across the arctic.10 It’s clear that the arctic’s temperature is rising, and
faster than that of the rest of the globe. This rapid warming will also reduce the extent of
the sea ice in the Arctic Ocean and increase its salinity.
Figure 6. Surface Temperature Anomaly Compared to 1951-1980 Average
Fresh Water in Arctic Ocean
There is for sure a lot of fresh water in the Arctic Ocean. And fresh water exiting the
Arctic in both the upper ocean and the sea ice cover plays a major role in controlling
8
http://news.bbc.co.uk/2/hi/8236797.stm
http://theblanketeffect.blogspot.com/2007_10_28_archive.html
10
http://www.gci.org.uk/Documents/Hansen_20120119_Temperature.pdf
9
convection in the North Atlantic, and consequently the global thermocline circulation
[Aagaard and Carmack, 1989;Walsh and Chapman, 1990; Serreze et al., 2006; Peterson et al., 2006]. In
2008 some measurements confirm that the upper ocean in the western Arctic was
extremely fresh compared with climatological conditions. According to the Third
Assessment Report of the International Panel on Climate Change, the ice contained
within Greenland Ice Sheet represents a sea-level rise equivalent of 7.2 metres (24 feet).
Variability of Arctic Ice
A pronounced reduction in the Northern Hemisphere sea-ice extent, such as seen in the
satellite record of the last two decades, is scarcely apparent in the early twentieth-century
warm period, at least in the two most widely-used century-long sea-ice data sets.
From 1953–2006, Arctic sea ice extent at the end of the summer melt season in
September has declined at a rate of 7.8%/decade. Over the period of modern satellite
observations (1979 – 2006) the trend is even larger (9.1% per decade). In 2011, NASA
announced that the area of Arctic ice is now almost as low as it was in 2007, its historic
minimum.The extent of ice reduced to 4.33 million km² in 2011 compared to the mean
(1979 to 2000) of 7.04 million km²(Stroeve, Holland et al. 2007).
Figure 7. Annual sea-ice extent (area within the ice-ocean margin) derived from a new "Zakharov" sea-ice data
set (red), Northern Hemisphere sea-ice extent from the widely used 'Walsh' data set (green) and zonal (70-90°N)
mean annual SAT (black) since 1900. The time series shown are 5-yr running means.
The 2011 event went relatively unnoticed, unlike that in 2007, which stirred significant
international media attention. Media and political dialogues have focused society’s
concerns on the Global Financial Crisis (GFC), diverting attention away from climate
change.
Figure 8. Monthly anomalies or departures from the mean and seasonal cycle. The linear trend was -0.34 x 105
km2 per decade during the period. The largest negative anomaly is found in the most recent data, with recordlow ice cover in September 2002.
Twentieth century the central Arctic Ocean became increasingly saltier with a rate of
freshwater loss of 239km3/ decade.
The western Arctic has gained in excess of 11,000 km3 of fresh water, while the Eurasian
basin lost about 3,300 km3 for a net gain of 7,700 km3, equivalent to roughly four times
the GSA
The IPCC (Intergovernmental Panel on Climate Change) AR4 models indicate an
essentially ice-free Arctic Ocean in September (less than 106 km2) may be realized
anywhere from 2050 to well beyond 2100.
Figure 9. Arctic September sea ice extent (x 106 km2) from observations (thick red line) and 13 IPCC AR4
climate models, together with the multi-model ensemble mean (solid black line) and standard deviation (dotted
black line). Models with more than one ensemble member are indicated with an asterisk. Inset shows 9-year
running means.
Consequences of ice loss
The loss of Arctic sea ice will have a dramatic impact on polar bears and other species
that hunt among the ice floes, but it will also trigger erratic shifts in climate that will be
felt around the world, scientists believe. The bitter Arctic fronts that blow across
Colorado and the western United States may warm and bring less snow, while winter
storm tracks across parts of Europe are expected to intensify and unleash torrential
downpours.
Summer ice loss will trigger rapid changes in the Arctic. The Arctic marine ecosystems
contain multiple elements that will shift in an abrupt manner when forced beyond their
tipping point. This will lead to changes in food webs and species loss.
The reduced ice extent is expected, in turn, to set a number of additional physical,
chemical and biological elements in motion, inducing rapid changes in the Arctic
environment.
These include:
•warming of seawater
•increased freshwater discharge
•loss of permafrost and ice sheets
•increased emissions of methane (a powerful greenhouse gas)
•a reduced capacity to sequester CO₂
•changes in atmospheric circulation and chemistry, including the recent development of
an ozone hole over the Arctic
All of these environmental changes have potential global consequences for the earth
system and humanity.
The causes of Sea Ice Change
The Arctic has often been viewed as a region where the effects of Green Houses Gases
loading will be manifested early on, especially through loss of sea ice. Sea temperatures
in the Arctic have increased 3C in recent decades due to a buildup of greenhouse gases in
the atmosphere, according to Mark Serreze, who led the study at the University of
Colorado, Boulder. He fears continued thinning of the ice will lead to a sudden
acceleration of melting that will leave the ocean ice-free.
The Beaufort Gyre is a wind-driven ocean current located in the Arctic Ocean polar
region. The Beaufort Gyre ("rotating pattern") slowly swirls the surface waters of the
Arctic basin, turning the Polar Ice Cap along with it. It makes one complete rotation
about every 4 years.
The Transpolar Drift carries water and ice from Siberia, across the Pole and down the
east coast of Greenland, where it joins the East Greenland current. This current is caused
by the inflow from Siberian rivers, and a westerly wind that pushes Arctic surface water
eastward into the Atlantic.
Figure 10. Arctic Ocean Circulation
The Fram Strait builds a seaway from the North Atlantic to the Arctic Ocean.Arctic
ocean circulation with a large increase in northward transport of freshened water in the
Canada Basin, toward the Fram Strait and Canadian Archipelago passages to the North
Atlantic.
Significant heat transfer
As known, there is more solar heating and evaporation at Equator, less at Poles. So
salinity and temperature between Equator and Pole are different and there must be
existing salinity and temperature gradient which cause warm and salty water moved from
Equator to polar.
Figure 11. Major surface ocean currents. Poleward-moving currents are warm, and equatorward-moving
currents are cold. Surface ocean currents are driven by global winds and play an important role in
redistributing heat around globe.
Questions for Discussion
1. Do you think the Arctic Ocean melting would increase the sea level? Why or
why not.
2. Would Ice melting influence the climate? Why or why not.
3. Do you think Arctic climate change influences people directly enough that they
can be persuaded to work against it?
4. How can we break the cycle of Arctic warming?
References
Arctic sea ice decline: Faster than forecast. http://www.athropolis.com/arcticfacts/fact-currents-2.htm
Peterson, B. J., J. McClelland, R. Curry, R. M. Holmes, J. E. Walsh, and K. Aagaard
(2006), Trajectory shifts in the Arctic and subarctic freshwater cycle, Science, 313, 1061
– 1066.
Mapping Areas Potentially Impacted by Sea Level Rise.
http://climategem.geo.arizona.edu/slr/us48prvi/index.html
Arctic Climate Impact Assessment. http://amap.no/acia/
European cold snap threatens energy crisis as death toll rises.
http://www.guardian.co.uk/world/2012/feb/03/europe-cold-energy-death-toll
Warm Arctic – Cold Continent.
http://www.arctic.noaa.gov/future/warm_arctic_cold_continent.html
Arctic ‘warmest in 2000 years.’ http://news.bbc.co.uk/2/hi/8236797.stm
The Blanket Effect. http://theblanketeffect.blogspot.com/2007_10_28_archive.html
Global Temperature in 2011, Trends, and Prospects.
http://www.gci.org.uk/Documents/Hansen_20120119_Temperature.pdf