http://dailynews.yahoo.com/news?tmpl=story2&cid=570&ncid=753&e=1&u=/nm/20020719/sc_nm/environment_glaciers_dc_1
Melting
Alaskan Glaciers Raise Sea Level
Fri Jul 19, 2002 3:25 PM ET
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters)
- Alaska's glaciers are melting so badly
that they are raising the world's overall sea level more than
any other single source, scientists said on Friday.
The melting glaciers
are responsible for at least 9 percent of
the rise in the world's sea level over the past century
-- adding more than one-tenth of a millimeter (.04 inch) each
year
to overall sea level, the researchers said.
That is far more than
anyone thought, and more than what was
produced by what was until now believed to be the biggest single
known source -- the melting Greenland ice sheet.
"Most glaciers
have thinned several hundred feet at low elevations
in the last 40 years and about 60 feet at higher elevations,"
Keith Echelmeyer, a glaciologist at the University of Alaska
Fairbanks Geophysical Institute who led the study, said in a
statement.
"Data from
our study indicates that Alaska glaciers are contributing
the most to the sea level rise that has been measured," said
Anthony Arendt, a graduate student listed as first author on
the study.
The team of researchers
used a laser altimetry system rigged up
to a small airplane, which Echelmeyer flew over 67 of Alaska's
mountain glaciers. They compared their readings to measurements
taken by the U.S. Geological Survey in the 1950s.
Writing in the
journal Science, they said the glaciers had lost,
on average, more than half a meter a year in height, or more
than a foot and a half.
ENOUGH WATER
TO RAISE SEA LEVEL
This added up to a
lot of water -- enough to raise the overall
level of the world's oceans measurably.
"(One-tenth of
a millimeter) seems like small amount but that
can cause a fair amount of transgression of water onto an area
where people live near coastal regions," Arendt said
-- especially if the shoreline is flat.
Many people in countries
such as Bangladesh and some island
nations live along flat coastlines and estuaries that can be
severely affected by small changes in sea level.
In 2001 Echelmeyer's
team flew over the same glaciers they
had measured in the early 1990s, and to their amazement found
that the glaciers were thinning at double the rates of
40 years before.
Echelmeyer, Arendt
and colleagues said they could not go
so far as to blame the melting on global warming.
"We can't really
make that link," Arendt said. "It's not really
our job. But (global warming) is consistent with other things
going on, with increasing rates of warming in other parts of
the world," he added.
"Certainly the
fact that the thinning rate of the glaciers has
doubled in the past 10 years indicates that something is going
on in Alaska -- warmer summers or less precipitation in winter."
There is, however,
plenty more water locked up in these glaciers,
the researchers noted. "Glaciers in Alaska and neighboring
Canada
cover 90,000 square kilometers, or about 13 percent of the
mountain glacier area on Earth, and include some of the largest
ice masses outside of Greenland and Antarctica," they wrote.
Some Antarctic glaciers
are also melting, as are some ice sheets,
but parts of the continent are adding ice, so the picture there
is complicated.
