Download Ice Sheets ESS Compilation B > A > E > H > B>A Human activities

Ice Sheets ESS Compilation
B > A > E > H > B>A
Human activities have increased the levels of greenhouse gases in the atmosphere and
have thus augmented global temperatures (1). Greenhouse gases include water vapor, carbon
dioxide, and methane, and they are part of the Greenhouse Effect. The Greenhouse effect is a
naturally occurring phenomenon that helps
regulate the temperatures on Earth. However,
since the industrial revolution, humans have
rapidly increased the amount of greenhouse
gases in the atmosphere, thus increasing their
effectiveness in keeping Earth warm. For
example, the burning of fossil fuels (coal,
natural gas, oil) has caused concentration of
carbon dioxide in the atmosphere to increase
from about 280ppm in pre-industrial times to
386ppm in 2008 (2). Furthermore the
Figure 1: Atmospheric concentrations of carbon dioxide and
transformations of forests to cattle ranches
methane (IPCC, 2007).
and rice paddies have increased the amount of methane
in the atmosphere. Methane
concentrations have risen from 700 ppb in pre-industrial times to 1775ppb in 2005 (3) (see
Figure 1). Thanks to the human actions and their consequential influence on the Greenhouse
Effect, over the past century average global temperature has risen 1.3oF and will reach an
increase of 3oF to 7oF by 2100 if emission of greenhouse gases remain at the current rates (1).
Arctic temperatures, however, have been affected far more dramatically than the global
average. Winter warming has exceeded 4 oC in
some Arctic regions. In response to these higher
temperatures, extent of arctic ice has also been
declining (13). Each year in the Arctic in the
beginning of summer, the ice cap covering the
North Pole, start to recede and regenerate at the
onset of winter. According to Ocean
Conservancy, scientists have been measuring the
ice caps in the middle of the summer since 1979.
The scientists report that, “In 2005 the extent of
sea-ice was 20% lower than 1979”, which is
certainly a troubling trend (see Figure 2).
Then, just two years later, in 2007, the cap
receded to a level 43% lower than the 1979
Figure 2: Seasonal and annual Northern Hemisphere sea ice
measurement—a rate that startled everyone,
extent. (University of Illinois, 2008)
including scientists. If this trend continues, the North Pole could be entirely devoid of summer
sea ice by 2050” (10).
The increase in global temperatures can cause sea levels to rise due to the natural
expansion of seawater as it warms and the melting of land-based ice (see Figure 3). According
to Roach (2006), sea levels globally have risen an estimated 0.1 inch a year over the past decade
(4). Many scientists fell that it is possible for
global sea levels would rise and estimated 20 -21
feet if all of the ice on Greenland were to melt
into the North Atlantic Ocean. Greenpeace
organization estimates that the Antarctic ice sheet
holds enough frozen water ( 60% of Earth’s
freshwater is stored in these sheets) to make sea
levels rise 203 feet (7).
This rise in sea level will greatly affect
coastal ecosystems. As sea level rises, existing
coastal marshes and mangrove ecosystems will
be eroded away. Rising water levels will create
new wetlands, however it is anticipated that these
new systems will be significantly smaller due to
human structures (see Figure 4). By 2080, as
3 (EPA,into
2009)
much as 33% of the world’s coastal ecosystems couldFigure
be flooded
open water systems (1).
The EPA estimates that a two-foot rise in
sea level would lead to 17-43% of American
wetlands being lost.
Furthermore, according to the
Nature Conservancy, some of the most atrisk ecosystems from sea level rise are
mangroves. Mangroves systems with little
sedimentation and on low relief islands are
especially in danger. Mangroves are
especially important to the biosphere
because they provide a habitat and nursery
area for many animals, and also produce
oxygen through photosynthesis. Though
the process the mangroves absorb carbon
dioxide and expels oxygen into the
Figure 4: Wetland ecosystem loss by rising sea level
atmosphere. If the mangroves die off, there will be less carbon dioxide absorbed, thus increasing
the amount of carbon dioxide emitted into the atmosphere. As stated earlier, the more carbon
dioxide there is in the atmosphere, the warmer global temperature will become.
References:
1. Intergovernmental Panel on Climate Change (IPCC). (2007). Changes in Atmospheric
Constituents in Radiative Forcing. Climate Change 2007: The Physical Science Basis.
Cambridge University Press: Cambridge, U.K.
2. Hofmann, D.J., Butler, J.H., Tans, P.P. (2009). A new look at atmospheric carbon
dioxide. Atmospheric Environment 43(12), 2084-2086
3. University Corporation for Atmospheric Research (UCAR). (2007). Climate and global
change. Windows to the Universe. Retrieved from
http://www.windows.ucar.edu/tour/link=/earth/climate/climate.html
4. Roach, J. (2006). Greenland Ice Sheet Is Melting Faster, Study Says. National
Geographic News. Retrieved from :
http://news.nationalgeographic.com/news/2006/08/060810-greenland.html
5. (2006). Study Previews Ice Sheet Melting, Rapid Climate Change. Retrieved from :
http://www.sciencedaily.com/releases/2006/03/060312210108.htm
6. (2004) A Chilling Possibility. Retrieved from:
http://science.nasa.gov/headlines/y2004/05mar_arctic.htm
7. http://www.greenpeace.org/international/campaigns/oceans/globalwarmingoceans
8. http://pubs.usgs.gov/fs/fs2-00/
9. http://www.theglobaleducationproject.org/earth/global-ecology.php
10. http://www.oceanconservancy.org/site/News2?page=NewsArticle&id=10341
11. http://earthobservatory.nasa.gov/Features/Water/water_2.php
12. http://www.oceanconservancy.org/site/News2?page=NewsArticle&id=10341
13. University of Illinois Polar Research Group (2008). The Cryosphere Today. Retrieved
from http://arctic.atmos.uiuc.edu/cryosphere/
E>H>A
The water in our world's oceans is constantly moving whether it is pushed and pulled by tides or blown
by waves. Through the force of the Great Ocean Conveyor Belt (also called the thermohaline
circulation) the ocean is gradually circulating around the globe. One of the most well known parts of the
Great Ocean Conveyor is the Gulf Stream and North Atlantic Drift, which helps give Europe a somewhat
moderate climate. Because it is powered by distinctions in water temperature and salinity, the melting
of a large part of the Arctic ice could switch off, slow down or divert the Great Ocean Conveyor. Salt
water freezes at a lower temperature than
fresh water. At the poles, ocean salinity is
about 35 ppt, and sea water begins to
freeze at -1.8 degrees Celsius (5). As the sea
water freezes, salt is excluded and
concentrated into liquid droplets of
extremely saline brine, which are expelled
back into the ocean. The formed ice will
eventually be fresh enough to drink as the
brine drains out (5). This expelled brine
causes the water around the sea ice to be
extremely saline and denser than
Figure 5: The global oceanic conveyer belt, is a unifying concept
surrounding water, causing it to sink. This
that connects the ocean's surface and thermohaline (deep mass)
cold and dense polar water moves along the
circulation regimes, transporting heat and salt on a planetary
ocean bottom towards the equator, where
scale.
it warms and rises, and travels along the
surface back to the poles (see Figure 5). However, as sea ice melts and introduces fresh water to polar
oceans, thermohaline circulation can be disrupted. Australian scientists feel that the melting ice could
release too much fresh water and could get in the way with the formation of dense "bottom water,"
which sinks 4-5 kilometers to the ocean floor. A slowdown in the system known as "overturning
circulation" (2009) could have a great affect on the way the ocean carries heat around the globe.
Unfortunately, if the ocean water salinity drops too low, the Great Ocean Conveyor will not be able to
make water cold and salty enough to sink. “Only a few places around Antarctica and in the northern
Atlantic create water dense enough to sink to the ocean floor, making Antarctic "bottom water" crucial
to global ocean currents”. The interplay between ocean and atmosphere is one of the keys to
understanding Earth’s climate. Wind not only helps redistribute heat around the world and help drive
ocean surface currents. Currents in turn redistribute the heat the ocean carries and play a major role in
shaping global temperature and rainfall patterns. For example, Europe is relatively warm because ocean
currents circulate heat from the equator up the east coast of North America, and westward to Europe.
As the warm surface water cools as it reaches Europe, heat is released to the atmosphere (5). As
phenomenon such as El Niño demonstrate, even subtle shifts in winds and surface currents can
profoundly impact temperature and rainfall patterns both locally and globally.
References:
1. Byrnes, M. (2009).Southern Ocean current faces slowdown threat. Retrieved from :
http://www.asoc.org/Portals/0/pdfs/Southern%20Ocean%20current%20faces%20slowdown%2
0threat.pdf
2. Ewing, B (2009). Warming oceans could shift earth’s axis. Retrieved from:
http://news.nationalgeographic.com/news/2008/03/080314-warming-quakes.html
3. http://www.greenpeace.org/international/campaigns/oceans/globalwarmingoceans
4. http://www.theglobaleducationproject.org/earth/global-ecology.php
5. University of Colorado at Boulder National Snow and Ice Data Center. All About Sea Ice.
Retrieved from: http://nsidc.org/seaice/index.html
E>L>A>H>H>L
It is well known that the rising global temperatures cause ice to melt. The resulting meltwater
percolates down the cracks of the ice. However, what happens in the invisible region
underneath where the ice meets rock, soil, and water is still largely unknown. Moreover,
Greenland ice sheet spills out through gaps in the mountain rim, and the glaciers cover deep
narrow valleys. According to van der Veen and other scientist, Greenland valleys have higher
than usual geothermal gradients. As a result, it may be geothermal heat rather than global
warming that causes some of the Greenland glaciers to have higher than usual flow rates.
Furthermore, in parts of the world, glaciers have been receding since 1895 and with an
increasing pace since 1930 and to date there are no obvious explanations for this and the dates
have no clear counterpart in temperature or carbon dioxide records. When the ice accumulates,
there can be a delay in the bedrock sinking for thousands of years which cause the ice sheets to
be positioned at a higher elevation and more positive ice mass that results in the ice growing
faster. However, during ice melting, the bedrock rebound can also be delayed for thousands of
years but ice sheets are positioned at lower, warmer elevation which causes negative ice mass
balance which results in the ice melting faster. The flow of ice is generally slow also known as
glacially slow. In Greenland, the Upernivek Glacier in Greenland flows at about 40 meters per
day. As the ice sheet melts and reaches a lower altitude, due to depressed land surface, where
the temperature is higher, it starts to melt and evaporate at the same time, a process called
ablation. If growth and melting are at a balance, the ice would be described as being
stationery. If precipitation exceeds melting, the ice would be described as growing and if
melting exceeds precipitation the ice would be described as receding (2). As ice sheets melt,
they can release pent-up energy and trigger massive earthquakes, according to new study.
Roughly 10,000 years ago a series of large earthquakes shook Scandinavia along fault lines
that are now quiet. Each earthquake occurred in roughly the same time period of the melting of
the thick ice sheets from the last ice age. Scientists think that the melting of the ice sheets
triggered the earthquakes by releasing the pressure that had been building up on Earth’s crust,
and triggered these earthquakes by releasing pressure that had built up in Earth's crust.
References:
1. Inman, M. (2008). Melting Ice Sheets Can Cause Earthquakes, Study Finds. National
Geographic News. Retrieved from:
http://news.nationalgeographic.com/news/2008/03/080314-warming-quakes.html
2. http://earthobservatory.nasa.gov/Newsroom/view.php?id=31651
3. http://icecap.us/images/uploads/OllierPaine-NoIceSheetCollapse-AIGNewsAug.2009.pdf
A>H>E>H>L
The hydrologic cycle, also called the water cycle is a model that describes the movement
and storage of water between Earth’s four spheres. On Earth, water can be stored in any of the
following reservoirs: atmosphere (water vapor), oceans, lakes, streams, rivers, groundwater, soil,
snowfields and ice sheets (glaciers and icebergs). Earth’s water can be continuously cycled
through threes reservoirs through process like condensation, precipitation, evaporation,
sublimation, transpiration, infiltration, groundwater flow and melting. According to
www.physicalgeography.net, 2.05 percent of Earth’s water is stored in ice caps and glaciers and
water lasts in glaciers for 20 to 100 years.
Meltwater contains both fluvial and glacial processes, therefore certain distinctive
landforms are found in glacial ablation environments or rather areas that have been affected by
the erosion of glaciers. They can be formed either by the erosion of ice or streams or a
combination of the two. Sediment that becomes deposited by glacial meltwater is called stratified
drift. Deposits of sediments from outwash streams are a little different. Outwash streams are
comprised mostly meltwater, and because of this are tied much closely to glacial ablation. It is
with this that outwash streams change with local climate conditions.
Table 8a: Hydrologic Cycle
Table 8b-1: Inventory of water at the Earth's surface.
Reservoir
Oceans
Volume (cubic km x 1,000,000) Percent of Total
1370
97.25
Ice Caps and Glaciers
29
2.05
Groundwater
9.5
0.68
0.125
0.01
Lakes
Soil Moisture
0.065
0.005
Atmosphere
0.013
0.001
Streams and Rivers
0.0017
0.0001
Biosphere
0.0006
0.00004
Table 8b-2: Typical residence times of water found in various reservoirs.
Reservoir
Average Residence Time
Glaciers
20 to 100 years
Seasonal Snow Cover
2 to 6 months
Soil Moisture
1 to 2 months
Groundwater: Shallow
Groundwater: Deep
100 to 200 years
10,000 years
Lakes
50 to 100 years
Rivers
2 to 6 months
Block diagram of the glacial drainage system.
References:
1. http://www.physicalgeography.net/fundamentals/8b.html
2. http://earthobservatory.nasa.gov/Features/Water/water_2.php
3. http://www.teachersdomain.org/resource/ipy07.sci.ess.watcyc.icesimulate/
E>L>B>A>H
The cryosphere is composed of all of the frozen water found in the hydrosphere. The two
components that comprise it are the continental or land ice and sea ice. Continental ice can be
found mainly in Greenland and Antarctica however you can also find smaller ones in China and
South America. Valley glaciers which are part of continental ice can actually be found on every
continent except Australia. Continental ice forms when snow accumulates on the surface of land
and over time compresses under the weight of snow on the surface. Snow accumulates during
the winter from precipitation and accumulates from the weight of the new snow. As the snow
melts, water filters into the snow and fills in the available air space and freezes at the snow-ice
boundary. The continental ice formation and flow process is generally very slow and the build
up or decay of ice sheets like valley glaciers can take decades or centuries. Sea ice is formed by
the freezing of sea water. Ocean water is salty, and when it freezes the salt is left in the water
and leaves the rest of the water around it denser and with a higher salinity. River and lake ice is
frozen mainly from fresh water generally and is therefore is not salty.
Melting of ground ice leads to thermokarst erosion- the ground surface subsides as ice
melts, causing depressions. These depressions tend to form melt lakes. Bacteria breaking down
this newly exposed organic-rich substrate carry out methanogenesis in the anaerobic
environment of the melt lake. Bubbling up methane from anaerobic methanogeneis in
thermokarst lakes could increase methane emissions to the atmosphere by 15-40%. Because
methane is a powerful greenhouse gas, this could provide a positive feedback to global warming,
leading to further ice melt (Walter, et al, 2006)
References:
1. Post, E., Forchhammer, M.C., Bret-Harte, M.S., Callaghan, T.V., Christensen, T.R.,
Elberling, B., Fox, A.D. (2009). Ecological dynamics across the Arctic associated with
recent climate change. Nature 325, 1355-1358.
2. Schiele, E. (2009). Melting Ice Sheets Impact. Retrieved from:
http://www.bbc.co.uk/climate/impact/glaciers.shtml
3. Walter, K.M., Zimov, S.A., Chanton, J.P., Verbyla, D., Chapin, F.S. (2006) Methane
bubbling from Siberian thaw lakes as a positive feedback to climate warming. Nature
443, 71-75.
4. United States Environmental Protection Agency (EPA). (2009). Frequently asked
questions about Global Warming and Climate Change: Back to basics. Retrieved from
http://www.epa.gov/climatechange/downloads/Climate_Basics.pdf
5. University of Illinois Polar Research Group (2008). The Cryosphere Today. Retrieved
from http://arctic.atmos.uiuc.edu/cryosphere/
6. http://earth.rice.edu/mtpe/cryo/cryosphere.html
B>A> E> L>H> A>B
Human activities have increased the levels of greenhouse gases in the atmosphere and have thus
augmented global temperatures. Greenhouse gases include water vapor, carbon dioxide, and
methane, and they are part of the Greenhouse Effect. The Greenhouse effect is a naturally
occurring phenomenon, that helps regulate the temperatures on Earth. However, since the
industrial revolution, humans have rapidly increased greenhouse gases and thus have rapidly
increased their effectiveness in keep planet earth warmer. For example, the burning of fossil
fuels (coal, natural gas, and oil) has caused concentration of carbon dioxide in the atmosphere to
increase from about 280ppm in pre-industrial times to 386ppm in 2008. Furthermore the
transformations of forests to cattle ranches and rice paddies have increased the amount of
methane into the atmosphere. Methane concentrations have risen from 700 ppb in pre-industrial
times to 1775ppb in 2005. Thanks to the human actions and their consequential influence on the
Greenhouse Effect, over the past century average global temperature has raised 1.3oF and will
reach an increase of 3oF to 7oF by 2100 if emissions of greenhouse gases remain at the current
rates.
Several of the studies on climate changed propose that the greatest amount of temperature
increases are occurring or will occur over Earth’s poles, where the largest ice sheets are located.
In fact, data records on Antarctica’s show that the continent’s average surface temperature has
increased about .05 degrees Celcius per decade since 1957. Not surprisingly, another scientific
study conducted by Johannessen from 1978 to 1995 indicates that the arctic sea ice has been
decreasing about 2.7% per decade. There is a strong link between global temperature increase
and ice sheet decline, leading many scientists to believe that global warming may be the
underpinning cause of the melting. For example, a five nation scientific team claims that a small
increase in carbon dioxide, a greenhouse gas that triggers global warming, may affect the
stability of the West Antarctic Ice Sheet and may even cause it to disappear over time, in
approximately 1000 years. Furthermore, research by NASA Goddard scientists show that when
the temperatures are warmer, the ice sheets of Greenland are moving quicker. Higher
temperatures melt ice sheets first around the outside and it takes a very long time for it to affect
the middle. Jim Swenson, a scientist and teacher, explained that this is similar to a piece of cloth
that is cut at one border with scissor, so that if the cloth is shaken or rubbed the handing threads
at the edge are ready to come apart. It does not come apart in the middle, just on the edges.
Similarly, when heat is added to the exterior of the ice, the water molecules on the outside that
were once glued together as ice, begin to turn to water molecules and join together. By melting,
the molecules use up some of the heat energy, thus protecting the interior. But some of the heat
energy gets near and melts the interior. As one Copenhagen scientist explains, “the areas lying
near the coast begin to decrease in size, because the ice is melting at the edge. When the ice
melts at the edge, it slowly causes the entire ice sheet to 'collapse' and become lower.” Thus there
are many examples and strong evidence to show that increasing global temperatures have
resulted in ice sheet retreat.
Ice sheets, long expanses of snow and ice, have very high albedos, or an ability to reflect
incoming solar radiation back into space. However, as ice sheets melt and turn into ocean
landscapes, the earth begins to absorb almost four times as much solar energy. High latitude
ocean albedo is typically near 10%; while snow or ice covered albedo at the same latitude can
reach as high as 60% (Hartmann 1994). This is because snow and ice are a lighter color than the
ocean’s surface, and the lighter the colors reflect more wavelength of light than darker colors.
Think about a really hot Florida day, would one be hotter wearing a black shirt or a white shirt?
Black, of course, because it absorbs more wavelengths of light. So, if the ice turns to ocean, more
solar radiation will be absorbed, and the warmer the temperatures on earth will become. This will
lead to more ice melting and the less solar radiation will be reflected and the cycle begins all
over again. This process is called the ice-albedo feedback and is particularly alarming in the
context of ice sheet melting because it could potentially rapidly increase the speed of their
retreat.
Loss of Arctic ice and snowpack from global warming and the
ice-albedo feedback severely threatens the viability of species
which depend on sea ice for hunting, reproducing, or avoiding
predators (Post et al, 2009). Polar bears are considered by
wildlife biologists to be “highly pagophilic,” literally meaning
they are “ice-loving” and indicating the extreme dependence the
species has on ice. Polar bear populations have declined by 22%
in Canada’s Hudson Bay and by 50% in Alaska’s Beufort Sea
(Post et al, 2009). The USGS has projected that 75% of the
polar bear population will be gone by 2050 due to ice loss
Polar bears resting on sea ice
(Glick, 2007). Canadian Wildlife Service has also documented
polar bears displaying decreased weight and lowered
reproductive rates in Canada’s James and Hudson Bays. The average weight of a mature female
bears fell from 650 pounds in 1980 to 507 pounds in 2004(Glick, 2007). The number of recorded
drowned polar bears has also shown a disturbing increase. This is attributed to retreating ice
forcing bears to swim increasingly long distances to reach ice large enough on which to rest
(Glick, 2007). Melting ice has also lead to increased cub mortality as dens collapse and either
crush or reduces insulation and exposes newborns to hypothermia and predation (Post et al,
2009). Den collapse is also a growing cause of mortality for ringed seals, which also create birth
dens within ice or snow pack (Post et al, 2009).
However, other animals benefit from retreating ice sheets. Earlier spring melt will lengthen
growing seasons. Plant species have already be found to flower up to 20 days earlier over the
last decade. Ice melt has also favored reindeer populations as winter mortality decreases and
reproductive rates increase (Post et al, 2009). Polar species are often highly adapted ice cover.
As ice retreats, however, invasive species can immigrate into newly ice-free areas and outcompete specialized species. For example, red foxes are currently displacing Arctic foxes from
their traditionally ice and snow-covered territories. Finally, milder ice-free conditions also allow
new parasites and insects to invade Arctic ecosystems. For example, the winter moth is currently
moving northward and feeding on birch forests traditionally outside its range (Post et al, 2009).
http://www.nytimes.com/2008/01/08/science/earth/08gree.html
^ Deser, C., J.E. Walsh, and M.S. Timlin (2000). "Arctic Sea Ice Variability in the Context of
Recent Atmospheric Circulation Trends". J. Climate 13: 617–633. doi:10.1175/1520-
0442(2000)013<0617:ASIVIT>2.0.CO;2. http://ams.allenpress.com/perlserv/?request=getabstract&doi=10.1175%2F1520-0442(2000)013%3C0617:ASIVIT%3E2.0.CO%3B2&ct=1.
http://esseacourses.strategies.org/private/learner.module.php?course_id=276&coursemodule_id=
656&cycle=A&cycle_label=4
http://www.worldclimatereport.com/index.php/2006/10/11/antarctic-ice-sheet-and-the-plotthickens/
http://www.ens-newswire.com/ens/mar2006/2006-03-13-03.asp
http://www.newton.dep.anl.gov/askasci/gen01/gen01520.htm
University of Copenhagen (2009, September 17). Melting Of The Greenland Ice Sheet Mapped.
ScienceDaily. Retrieved September 30, 2009, from http://www.sciencedaily.com
/releases/2009/09/090916133508.htm
Clement, A.C., Burgman, R., Norris, J.R. (2009) Observational and model evidence for positive
low-level cloud feedback. Science 325, 460-464.
Hofmann, D.J., Butler, J.H., Tans, P.P. (2009). A new look at atmospheric carbon dioxide.
Atmospheric Environment 43(12), 2084-2086
Intergovernmental Panel on Climate Change (IPCC). (2007). Changes in Atmospheric
Constituents in Radiative Forcing. Climate Change 2007: The Physical Science Basis.
Cambridge University Press: Cambridge, U.K.
United States Environmental Protection Agency (EPA). (2009). Frequently asked questions
about Global Warming and Climate Change: Back to basics. Retrieved from
http://www.epa.gov/climatechange/downloads/Climate_Basics.pdf
University Corporation for Atmospheric Research (UCAR). (2007). Climate and global change.
Windows to the Universe. Retrieved from
http://www.windows.ucar.edu/tour/link=/earth/climate/climate.html
H>B>A> E> H> A>L
Ice sheets basically originate and form in places where the snow that falls in the winter
does not melt entirely over the summer, such as Greenland. Over the years, layers of snow begin
to pile up into thick masses of ice. The ice layers grow thicker and become denser as the weight
of new ice compresses the old layers.
It is believed that because of an increased in global temperatures due to anthropogenic
causes, ice sheets could possibly be thickening. In contradiction to scientists who believe that ice
sheets will continue to retreat, some scientists believe that the retreat of ice sheets will be offset
by increased snowfall. Increases in global temperatures may help new ice sheet growth because
ice sheet growth relies more on moisture and very heavy snowfall than colder temperatures
(Johnson, secrete of ice ages).Basically, a warmer atmosphere can hold and transfer more water
vapor, which will turn to snow when it freezes, than a colder atmosphere. For instance, global
climate change modules predict that since the climate is warmer over Antarctica, snow fall
should actually increase because the warmer atmosphere can hold more moisture. If snow fall
and accumulation increases, then it is assumed that ice sheets should thicken.
This is supported by new research by Joughin and his team of scientists, who discovered
that the West Antarctic Ice was actually thickening. Ice sheets are also constantly moving. They
slowly flow downhill from the pressure of their own weight. According to the National Snow
and Ice Data Center, “Near the coast, most of the ice moves through relatively fast-moving
outlets called ice streams, glaciers and ice shelves. As long as an ice sheet accumulates the same
mass of snow as it loses to the sea, it remains stable.” Joughin and his team studied the flow of
ice streams that run from the middle of the ice sheet to the ocean. Since the water runoff is
decreasing, the ice sheet must be holding onto the water, which would thus cause it to thicken.
References:
http://www.scienceagogo.com/news/20020927213400data_trunc_sys.shtml
http://www.aip.org/history/climate/floods.htm
http://www.worldclimatereport.com/index.php/2006/10/11/antarctic-ice-sheet-and-the-plotthickens/
http://abcnews.go.com/Technology/story?id=98113&page=1
L>E>L>A>B
Some scientists purport that underground geothermal heating may be the cause for ice sheet
melting in Greenland. For example, according to van der Veen and other scientist, Greenland
valleys have higher than usual geothermal gradients. As a result, it may be geothermal heat
rather than global warming that causes some of the Greenland glaciers to have higher than usual
flow rates.
Many scientists feel that is possible for global sea levels to raise an estimated 20-21feet if all of
the ice of Greenland were to melt into the North Atlantic Ocean. The melting of ice and rise in
sea levels around Greenland has severely impacted wildlife. For example, although walrus are
more of a marine species, they still depend on sea ice for resting. Retreating ice has forced
walrus to travel farther to forage, and scientists have noted an alarming increase in abandoned
walrus pups which have become separated from their mothers as they travel farther out to sea.
These lone pups have almost no chance at survival (Post et al, 2009). Furthermore, as floating
ice becomes unavailable, walrus have gathered on rocky shores by the thousands. This
conglomeration has lead to increased mortality from trampling (Post et al, 2009).
Post, E., Forchhammer, M.C., Bret-Harte, M.S., Callaghan, T.V., Christensen, T.R., Elberling,
B., Fox, A.D. (2009). Ecological dynamics across the Arctic associated with recent climate
change. Nature 325, 1355-1358.
http://icecap.us/images/uploads/OllierPaine-NoIceSheetCollapse-AIGNewsAug.2009.pdf