The Heat Is Online

Patagonian Ice Melt Drives Sea Level rise

Study: Glaciers melting faster, changing sea level, Oct. 18, 2003

WASHINGTON (AP) --Melting of glaciers in the Patagonian ice fields of southern Argentina and Chile has doubled in recent years, caused by higher temperatures, lower snowfall and a more rapid breaking of icebergs, a study suggests.

Using satellites from the National Aeronautics and Space Administration and the Defense Department, researchers measured the loss from two ice fields on the southern tip of South America and found that the rate of melting doubled from 1995 to 2000 when compared with earlier measurements.

A report on the findings appear Friday in the journal Science.

The two ice fields cover a total of 6,600 square miles and contain 63 glaciers. Some dump their water into the ocean, while others flow into high lakes.

Researchers estimated that the glaciers are losing the equivalent of 10 cubic miles of ice every year now. This is enough to annually raise the world's sea level by about four-one thousandths of an inch, the scientists calculated.

This means that the mountain glaciers in Patagonia are contributing an unusually large amount of water to the sea when compared with some much larger ice fields, the researchers said.

Alaska, for instance, has five times more ice than Patagonia. Yet, the melt off from Patagonia is almost a third as much as the melt off from Alaska's mountain glaciers.

The researchers concluded that the Patagonia ice is melting faster now due to warmer air temperatures, a decrease in precipitation and a more rapid breaking of pieces of icebergs into the ocean, known as calving.

The study was conducted by Eric Rignot of the Jet Propulsion Laboratory in Pasadena, California; Andres Rivera of the University of Chile in Santiago, and Gino Casassa of the Center of Scientific Studies in Valdivia, Chile.

Copyright 2003 The Associated Press. All rights reserved

South American glaciers' big melt, Oct. 17, 2003

The Patagonia glaciers of Chile and Argentina are melting so fast they are making a significant contribution to sea-level rise, say scientists.

They report ice was lost at a rate sufficient to push up ocean waters by 0.04 millimetres per year during the period from 1975 through to 2000.

This is equal, the researchers say, to 9% of the total annual global sea-level rise from all mountain glaciers. The American research team reports its findings in the journal Science.

Rising temperatures

The team combined data from a space shuttle mission in 2000 and survey data gathered on the ground to study the 63 largest Patagonia ice fields.

They compared ice loss rates between 1968 and 1975, and from 1975 to 2000. As well as the general increase in melting, the team also found accelerated ice-mass loss between 1995 and 2000.

This period saw melting sufficient to push up sea-levels by 0.1 millimetres per year.

In comparison, the team says, Alaska's glaciers, which cover an area five times larger, account for about 30% of the total annual global sea-level rise from mountain glaciers.

The researchers, led by Eric Rignot, from the US space agency's Jet Propulsion Laboratory, believe climate change has led to the region experiencing a rise in air temperatures and decreased precipitation.

Going backwards

Still, those factors alone are not sufficient to explain the rapid thinning.

The rest of the story appears to lie primarily in the unique dynamic response of the region's glaciers to climate change, the researchers believe.

"The Patagonia ice fields are dominated by so-called 'calving' glaciers," Rignot said.

"Such glaciers spawn icebergs into the ocean or lakes and have different dynamics from glaciers that end on land and melt at their front ends.

"Calving glaciers are more sensitive to climate change once pushed out of equilibrium, and make this region the fastest area of glacial retreat on Earth," he said.