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Global Warming
Glacier Accelerates
Climate Change
Testimony
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Article courtesy of Project
Thin Ice
Project Thin Ice 2005 is a Greenpeace Inc. production. © Greenpeace, Inc.
Climate Change Impacts in the Arctic
The Earth's climate is changing:
average global temperatures have risen by approximately 1 degree Fahrenheit
(0.6 degrees Celsius) since the beginning of the last century. Such
increases are projected to not only continue, but increase-according
to the Intergovernmental Panel on Climate Change (IPCC), by anywhere
between 2.5 and 10.4 degrees Fahrenheit (1.4 to 5.8 degrees Celsius)
over the course of this century.
This warming is not, and will not be, uniform. Warming in the Arctic
is projected to be two to three times the global average; already,
temperature increases in the region are far exceeding those in more
temperate zones. In Alaska and western Canada, winter temperatures
have increased by as much as 5-7 degrees F (3-4 degrees C) over the
past fifty years; over the next 100 years, annual average temperatures
are projected to rise 5-9 degrees F (3-5 degrees C) over land and
up to 13 degrees F (7 degrees C) over the ocean. Winter temperatures
are projected to increase by 7-13 degrees F ( 4-7 degrees C) over
land and by 13-18 degrees F (7-10 degrees C) over the ocean.
Such wholesale changes are already having an impact throughout the
Arctic region, and the associated impacts will only become more pronounced
as warming continues.
Sea Ice
Sea ice (literally, the frozen surface of the sea) is an essential
element of the Arctic marine ecosystem. On its underside grows algae
which support the entire food chain. It provides shelter for species
such as arctic cod, and is an essential habitat for migratory birds,
for seals and walruses, for polar bears, and for Native peoples.
However, sea ice is in retreat throughout the Arctic. Over the past
thirty years, annual average sea ice extent has decreased by about
8%, or approximately 386,000 square miles (one million square kilometers),
an area the size of Texas and Arizona [Norway, Sweden, and Denmark]
combined. Additional declines of 10-50% in annual average sea-ice
extent are projected by 2100, with summer sea ice declines projected
to be around 50%, and some models predicting near-complete disappearance
of summer sea ice.
The remaining sea ice is also thinner. Reductions in average thickness
levels across the Arctic are estimated at 10-15%, with some areas
showing reductions of up to 40% between the 1960s and late 1990s.
Glaciers
With increasing temperatures, most glaciers have been in retreat across
the Arctic since the early 1960s, a trend that sped up in the 1990s.
About half of the estimated loss of mass in glaciers worldwide is
in western Alaska, while seasonal surface melt on the Greenland ice
sheet—by far the largest area of land ice in the northern hemisphere—has
been increasing since satellite observations began in 1979. Climate
models predict that local warming over Greenland may be one to three
times the global average, which additional models suggest could eventually
lead to a near-complete melting of the Greenland ice sheet.
Habitat Change
Climate change is projected to cause northward shifts in vegetation,
and because warmer temperatures favor taller, denser vegetation, boreal
forests will encroach on the arctic tundra, and the tundra will shift
northward into the realm of the polar desert. The consequences of
such change will be varied and sometimes seemingly contradictory:
tree growth rates will increase in some areas and decline in others;
disturbances such as fires and floods will likely either speed up
or inhibit forest growth; and although the range of trees such as
black and white spruce may expand, higher temperatures and drier conditions
will make them more vulnerable to disease and to insect pests such
as the spruce bark beetle and the black-headed budworm, which in turn
will benefit from those changing conditions.
As a result of encroaching forests and rising sea levels, tundra area
is expected to shrink to its lowest extent in at least the past 21,000
years, potentially reducing the breeding area for many migratory bird
species and the grazing areas for land animals that depend on the
open landscape of tundra and polar desert habitats.
Wildlife Impacts
Changes in habitat will inevitably affect distribution and abundance
of associated wildlife populations. For example, mosses and lichens
are particularly vulnerable to warming—which, because they form the
basis of important food chains (providing, for example, primary winter
food sources for reindeer/caribou), will have significant repercussions
throughout the ecosystem. Caribou (the North American form of the
species Rangifer tarandus) and reindeer (Eurasian form of the same
species) will be affected not only by declines in some of their food
sources, but also by increased difficulty in reaching some of those
food sources as a result of climatic changes. For example, numbers
of Peary caribou on Canada's arctic islands plummeted from 26,000
in 1961 to 1,000 by 1997, apparently largely as a result of autumn
rains icing the winter food supply and crusting the snow cover, limiting
access to forage.
Mild weather and wet snow prompt the collapse of under-snow spaces
that provide burrows for lemmings and voles, affecting population
cycles of those species and leading to declines in their populations,
with impacts on their predators, such as snowy owls, skuas, weasels,
and ermine.
Changes in the thickness and extent of sea ice are likely to affect
the species which live on sea ice habitat, and indeed there is evidence
that such impacts are already occurring. For example, a 1999 study
showed that polar bears in Hudson Bay suffered 15% declines in average
weight and the number of cubs born between 1981 and 1998. These changes
are likely correlated to late sea-ice formation in fall and early
break-up in spring, which leads to a longer winter fasting period
for females, for whom healthy fat reserves are essential to survival
and reproductive success.
According to the Arctic Climate Impact Assessment, a study conducted
on behalf of the Arctic Council, polar bears "are unlikely to survive
as a species if there is an almost complete loss of summer sea-ice
cover, which is projected to occur before the end of this century
by some climate models."
Human Impacts
Melting of permafrost—the layer of permanently-frozen soil that is
a defining characteristic of polar and alpine environments—is already
causing collapses in the ground above it, leading to structural failures
in buildings and roadways throughout the Arctic and sub-arctic. Continued
melting is likely to make construction and transportation in the region
increasingly problematic. Conversely, disappearing sea ice is likely
to lead to significantly more navigable seaways: for example, the
navigation season for the Northern Sea Route (the passage across the
north of Russia from Novaya Zemlya to the Bering Strait) is projected
to increase from the current 20-30 days per year to 90-100 days by
2080. While this may be a boon to international commerce, it will
increase the risk of accidents, oil spills, and the chronic air and
water pollution associated with shipping activities.
Retreating sea ice and melting permafrost also increase the likelihood
of erosion in many areas. In some coastal Arctic regions, retreating
sea ice has left low-lying coastal areas more vulnerable to storm
surges, with sometimes dramatic consequences. The village of Shishmaref,
for example, located on an island off the coast of northern Alaska,
has been increasingly battered and damaged by storms. Several houses
have been evacuated and moved to high ground, and now the entire village
is likely to be relocated to the mainland.
For many Native peoples of the Arctic, a warming climate and subsequent
environmental changes are already profoundly altering their traditional,
subsistence way of life. For example, predicted northward movement
of sea ice is expected to reduce the availability of seabirds as food
resources for many arctic communities, while reduced sea ice extent
and thickness is also making it more difficult and dangerous to find
and hunt for marine mammals.
Global Consequences
Climatic changes in the Arctic have potential consequences for the
rest of the globe. Reductions in sea ice extent and snow cover cause
a reduction in surface reflectivity, meaning that more energy is absorbed
at the surface and less is radiated, causing further warming, which
in turn leads to further melting: what scientists refer to as a 'positive
feedback'.
Melting Arctic glaciers can also contribute to sea level rise. Global
average sea level rise is projected to rise between four inches and
three feet (10 to 90 centimeters) during this century, primarily due
to thermal expansion of the ocean and melting of glaciers and ice
caps, with the rate of rise accelerating as the century progresses.
Should the Greenland ice sheet melt completely, as models suggest
it could, that would result in a sea level rise of about twenty-three
feet (seven meters).
At the same time, melting arctic ice, combined with increased precipitation
and river runoff, may lead to a freshening of the ocean in the North
Atlantic, disrupting the critical salinity balance and leading to
a collapse in the ocean circulation pattern that brings warm water
to Europe from the tropics. As a consequence, global warming could
lead to regional cooling in the Northeast Atlantic region.
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