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Copyright © 2002 Earth Policy Institute
Ice Melting Everywhere
Lester R. Brown
Several new studies report that the earth's ice
cover is melting faster than projected by the Intergovernmental
Panel on Climate Change (IPCC) in its landmark report released in
early 2001. Among other things, this means that the IPCC team, which
did not have the ice melt data through the 1990s, will need to revise
upward its projected rise in sea level for this century—currently
estimated to range from 9 to 88 centimeters (4 to 35 inches).
A study by two scientists from the University
of Colorado's Institute of Arctic and Alpine Research found that
melting of the large glaciers on the west coast of Alaska and in
northern Canada is accelerating. Earlier data indicated that the
melting of glaciers in these areas was raising sea level by 0.14
millimeters per year, but new data for the 1990s indicate that the
more rapid melting is causing an increase of 0.32 millimeters a
year, more than twice as fast.
The Colorado study is reinforced by a U.S. Geological
Survey (USGS) study that indicates glaciers are now shrinking in
all 11 of Alaska's glaciated mountain ranges. An earlier USGS study
reported that the number of glaciers in Glacier National Park in
the United States had dwindled from 150 in 1850 to fewer than 50
today. It projected the remaining glaciers would disappear within
30 years.
See data
table.
Another team of USGS scientists, using satellite
data to measure changes in the area covered by glaciers, describes
an accelerated melting of glaciers in several mountainous regions,
including the South American Andes, the Swiss Alps, and the French
and Spanish Pyrenees.
Glaciers are shrinking faster throughout the Andes.
Professor Lonnie Thompson of Ohio State University reports that
for the Qori Kalis glacier, on the west side of the Quelccaya ice
cap in the Peruvian Andes, the annual shrinkage from 1998 to 2000
was three times that which occurred between 1995 and 1998. And that,
in turn, was nearly double the annual rate of retreat from 1993
to 1995. Thompson projects that the large Quelccaya ice cap will
disappear entirely between 2010 and 2020.
The vast snow/ice mass in the Himalayas, which
ranks third after Antarctica and Greenland in the amount of fresh
water stored, is also retreating. Although data are not widely available
for the Himalayan glaciers, those that have been studied indicate
an accelerating retreat. For example, data for the 1990s show that
the Dokriani Bamak Glacier in the Indian Himalayas moved back by
20 meters in 1998 alone, more than during the preceding five years.
Thompson has also studied Kilimanjaro, observing
that between 1989 and 2000, this famous mountain in Tanzania lost
33 percent of its ice field. He projects that the ice could disappear
entirely within the next 15 years.
Both the North and the South Poles are showing
the effects of climate change too. The South Pole is covered by
a continent the size of the United States. The Antarctic ice sheet,
which is 2.5 kilometers (1.5 miles) thick in some places, contains
over 70 percent of the world's fresh water and 90 percent of the
earth's ice.
While this vast ice sheet is relatively stable,
the ice shelves-the portions of the ice sheet that extend into the
surrounding seas-are fast disappearing. Over the past five years,
the Larsen B ice shelf on the Antarctic Peninsula has lost more
than 5,700 square kilometers of ice, half of which disappeared in
the early months of 2002. Delaware-sized icebergs that have broken
off are a threat to ships in the area.
While the South Pole is covered by a huge continent,
the North Pole is covered by the Arctic Ocean. Arctic sea ice is
melting fast. Over the last 35 years, the ice has thinned 42 percent—from
an average of 3.1 meters to 1.8 meters. It has also shrunk by 6
percent since 1978. Together, thinning and shrinking have reduced
the mass of sea ice by half. A team of Norwegian scientists projects
that the Arctic Sea could be entirely ice-free during the summer
by mid-century, if not before.
If this melting materializes as projected, the
early explorers' dream of a northwest passage—a
shortcut from Europe to Asia—could
be realized. Unfortunately, what was a dream for them could be a
nightmare for us.
If the Arctic Ocean becomes ice-free in the summer,
it would not affect sea level because the ice is already in the
water, but it would alter the regional heat balance. When sunlight
strikes ice and snow, most of it is reflected back into space, but
if it strikes land or open water, then much of the energy in the
light is absorbed, leading to higher temperatures. This is what
computer modelers refer to as a positive feedback loop, a situation
where a trend creates self-reinforcing conditions.
Richard Kerr, writing in Science, notes
that summer "would convert the Arctic Ocean from a brilliantly white
reflector sending 80 percent of solar energy back into space into
a heat collector absorbing 80 percent of [incoming sunlight]." The
discovery of open water at the North Pole by an ice breaker cruise
ship in August 2000 provides further evidence that the melting process
may now be feeding on itself.
This prospect of much warmer summers in the Arctic
is of concern because Greenland, which has the world's second largest
ice sheet, is largely within the Arctic Circle. In a Science
article in 2000, a team of U.S. scientists from NASA reported that
the vast Greenland ice sheet is starting to melt.
The team also reports that the melting there appears
to be accelerating because the ice sheet on its southern and eastern
edges has thinned by more than a meter a year since 1993. If all
the ice on Greenland were to melt, it would raise sea level by 7
meters (23 feet), but even under a high temperature rise scenario,
it could take many centuries for it to melt completely.
The accelerated melting of ice, particularly during
the last decade or so, is consistent with the accelerating rise
in temperature that has occurred since 1980. With the IPCC projecting
global average temperature to rise by 1.4-5.8 degrees Celsius (2.5-10.4
degrees Fahrenheit) during this century, the melting of ice will
likely continue to gain momentum.
Our generation is the first to have the capacity
to alter the earth's climate. We are also, therefore, the first
to wrestle with the ethical question of whether the capacity to
change the planet's climate gives us the right to do so.
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OTHER INFORMATION FROM THE EARTH POLICY
INSTITUTE
ECO-ECONOMY
UPDATES
Earth's
Ice Melting Faster Than Projected
This
Year May be Second Warmest Year on Record
Climate
Change Has World Skating on Thin Ice
BOOKS
Lester
R. Brown, Janet Larsen, and Bernie Fischlowitz-Roberts, The
Earth Policy Reader (New York: W.W. Norton & Company,
2002).
Lester R. Brown, Eco-Economy:
Building an Economy for the Earth (New York: W.W. Norton
& Company, 2001).
LINKS
Global Ice Measurements from Space
http://www.GLIMS.org
Institute of Arctic and Alpine Research, University
of Colorado
http://instaar.colorado.edu
Intergovernmental Panel on Climate Change
http://www.ipcc.ch
International Research Institute for Climate Prediction
http://iri.ldeo.columbia.edu/ climate/cid/index.html
National Snow and Ice Data Center
http://www-nsidc.colorado.edu
United Nations Framework Convention on Climate Change
http://www.unfccc.de
World Glacier Inventory
http://nsidc.org/data/glacier _inventory/index.html
World Glacier Monitoring Service
http://www.geo.unizh.ch/wgms
Worldwatch Institute Climate Mini Site
http://www.worldwatch.org/ topics/climate.html
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