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Close study of changes in the proliferation and size of icebergs allows scientists to better understand climate change in the Arctic and beyond.
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Icy indicators
Bergs are becoming an early warning system for global health
By Justin Brake
As scientists attempt to unravel the complexities of climate change there are two things that
most can agree upon: the climate is warming and ice is melting.
Like trusted canaries in a mine shaft, the shifting North
has become the main indicator of climate change and global health. |
With the Arctic warming twice as fast as the rest of the planet, it has become a prime microscope
for scientists to monitor changes in climate. Like trusted canaries in a mine shaft, the shifting
North has become the main indicator of climate change and global health.
Icebergs, imposing examples of the melting process, are an unavoidable indicator of current
warming trends in the Arctic. Polar ice is melting at an alarming rate, which means an increasing
number of icebergs are calving and drifting to deeper waters, becoming hazardous to offshore
structures, fishing boats and ship's navigation.
Dr. Martin Sharp, a glaciologist and chair of the Earth and Atmospheric Sciences department
at the University of Alberta, has done field work in the Canadian Arctic with the Environment
Canada program CRYSYS (Cryosphere System in Canada). Sharp concludes that the relationship
between icebergs and climate change is complex.
"There's been quite a bit of work on trying to understand the mechanics of producing
icebergs, but only very recently on whether it is related to climate change in some way," says
Sharp.
According to Sharp, there are two ways that icebergs may act as indicators. "One is
the amount and the other is the size. The really big ones, tabular icebergs, tend to break
off from large floating ice shelves or ice tongues," he says, an occurrence that has
been synonymous with increasingly warmer temperatures, particularly in Greenland and the
Antarctic.
"The decrease of these currents may contribute
to changes of climate in Europe and North America in the next 20 years."
—Dr. Martin Sharp |
"What we keep seeing is that it is possible to have this kind of
catastrophic break-up of ice shelves in a very short period of time, and when that happens
you release a lot of these icebergs into the ocean. There is some evidence that climate change
is implicated in these rapid break-ups taking place."
Sharp also describes how climate change may be linked to glacier surges ― a sudden
and significant increase in a glacier's rate of flow ― resulting in a highly quantitative
production of icebergs. "When glacier surges occur, the ice becomes intensely crevassed.
As they start to float into deeper water they tend to disintegrate because there are so many
fractures in them already. So these glaciers will produce very large numbers of medium-sized ‘bergs."
Beyond becoming lumbering obstacles in the ocean, this proliferation of icebergs could be
seen as an early warning of what is to come. With large volumes of the freshwater icebergs
entering the saltwater polar oceans, the global thermohaline circulation ― also
known as the global conveyor belt ― could be slowed down or halt. These currents are
responsible for bringing warm waters from the tropics to colder parts of the world, and the
decrease of these currents may contribute to changes of climate in Europe and North America
in the next 20 years.
Although the melting of Arctic ice will not directly effect sea levels, ocean currents will
be further effected as ice shelves break off, calving icebergs, the flow rate of ice streams
off land into the ocean will be accelerated and in turn raise the sea level.
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