[Mb-civic] Glacier Melt Could Signal Faster Rise in Ocean Levels - Washington Post

[William Swiggard]

Glacier Melt Could Signal Faster Rise in Ocean Levels

By Shankar Vedantam
Washington Post Staff Writer
Friday, February 17, 2006; A01

Greenland's glaciers are melting into the sea twice as fast as 
previously believed, the result of a warming trend that renders obsolete 
predictions of how quickly Earth's oceans will rise over the next 
century, scientists said yesterday.

The new data come from satellite imagery and give fresh urgency to 
worries about the role of human activity in global warming. The 
Greenland data are mirrored by findings from Bolivia to the Himalayas, 
scientists said, noting that rising sea levels threaten widespread 
flooding and severe storm damage in low-lying areas worldwide.

The scientists said they do not yet understand the precise mechanism 
causing glaciers to flow and melt more rapidly, but they said the 
changes in Greenland were unambiguous -- and accelerating: In 1996, the 
amount of water produced by melting ice in Greenland was about 90 times 
the amount consumed by Los Angeles in a year. Last year, the melted ice 
amounted to 225 times the volume of water that city uses annually.

"We are witnessing enormous changes, and it will take some time before 
we understand how it happened, although it is clearly a result of 
warming around the glaciers," said Eric Rignot, a scientist at the 
California Institute of Technology's Jet Propulsion Laboratory.

The Greenland study is the latest of several in recent months that have 
found evidence that rising temperatures are affecting not only Earth's 
ice sheets but also such things as plant and animal habitats, coral 
reefs' health, hurricane severity, droughts, and globe-girdling currents 
that drive regional climates.

The ice sheets in Greenland and Antarctica are among the largest 
reservoirs of fresh water on Earth, and their fate is expected to be a 
major factor in determining how much the oceans will rise. Rignot and 
University of Kansas scientist Pannir Kanagaratnam, who published their 
findings yesterday in the journal Science, declined to guess how much 
the faster melting would raise sea levels but said current estimates of 
around 20 inches over the next century are probably too low.

While sea-level increases of a few feet may not sound like very much, 
they could have profound consequences on flood-prone countries such as 
Bangladesh and trigger severe weather around the world.

"The implications are global," said Julian Dowdeswell, a glacier expert 
at the University of Cambridge in England who reviewed the new paper for 
Science. "We are not talking about walking along the sea front on a nice 
summer day, we are talking of the worst storm settings, the biggest 
storm surges . . . you are upping the probability major storms will take 
place."

The study also highlights how seemingly small changes in temperature can 
have extensive effects. Where glaciers in Greenland were once traveling 
around four miles per year, they are now moving twice as fast. While it 
is possible that increased precipitation in northern Greenland is 
somehow compensating for the melting in the south, the scientists said 
that is unlikely.

There are multiple ways warming might be causing glaciers to accelerate. 
The scientists said increased temperatures may loosen the grip that 
glaciers have on underlying bedrock, or melt away floating shelves along 
the shore that can hold ice in place.

Whatever the mechanism, the phenomenon seems widespread. At a news 
conference organized by the American Association for the Advancement of 
Science at its annual meeting in St. Louis, glacier scientists Vladimir 
Aizen from the University of Idaho and Gino Casassa of Chile's Centro de 
Estudios Cientificos said they were seeing the same thing happen to 
glaciers in the Himalayas and South America.

"Glaciers have retreated systematically and in an accelerated fashion in 
the last few decades," Casassa said. One glacier that provided Bolivia 
with its only ski slope five years ago has splintered into three and 
cannot be used for skiing, the scientist added.

Rapid melting of Himalayan glaciers also raises concerns for the large 
portion of humankind that gets its fresh water from glacier-fed rivers 
in South Asia, Aizen noted.

Most climate scientists believe a major cause for Earth's warming 
climate is increased emissions of greenhouse gases as a result of 
burning fossil fuels, largely in the United States and other wealthy, 
industrialized nations such as those of western Europe but increasingly 
in rapidly developing nations such as China and India as well. Carbon 
dioxide and several other gases trap the sun's heat and raise 
atmospheric temperature.

"This study underscores the need to take swift, meaningful actions at 
home and abroad to address climate change," said Vicki Arroyo, director 
of policy analysis at the Pew Center on Global Climate Change.

The data highlight the lack of meaningful U.S. policy, she added: "This 
is the kind of study that should make people stay awake at night 
wondering what we're doing to the climate, how we're shaping the planet 
for future generations and, especially, what we can do about it."

http://www.washingtonpost.com/wp-dyn/content/article/2006/02/16/AR2006021601292.html?referrer=email
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