Some Glaciers Growing Due to Climate Change, Study Suggests

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Fed by snowmelt and glacial runoff, a massive dam and irrigation system in the Indus Basin supplies water to farmlands that cover about 65,640 square miles (170,000 square kilometers).

The waters also drive hydroelectric power facilities at the Mangla and Tarbela Dams.

Hayley Fowler is lead author of the study and a senior research associate with Newcastle University's School of Civil Engineering and Geosciences.

"Our research suggests we could be able to predict in advance the volume of summer runoff, which is very useful in planning ahead for water resources and also the output from the dams," Fowler said in a statement.

About a third of the annual runoff comes from glaciers in the high mountain peaks and is regulated largely by summer temperatures.

The latest study suggests that a 1.8°F (1°C) drop in mean summer temperature since 1961 has cut that glacial melt by 20 percent.

But winter snowfall drives the remaining two-thirds of annual runoff. This volume has been increasing as snowfall totals rise.

Temporary Trend?

The data also reveal another climatic oddity—a change in the basin's diurnal temperature range, or the span between daytime high and nighttime low temperatures for a given day.

"There's a large increase in the diurnal temperature range observed in all seasons and in all the annual data sets," Archer said.

"In most parts of the world there's been a decrease in diurnal temperature change, and this is what's being predicted by global climate-change models."

All together, the area's regional variations are at odds with most glaciated regions worldwide, including the Eastern Himalaya, where glaciers have been shrinking significantly.

Lonnie Thompson, a paleoclimatologist and glacier expert at Ohio State University in Columbus, thinks the latest findings might be a short-term trend only.

"My guess is that the glaciers in [Haley and Fowler's] area of study might find short-term benefit where increased winter snowfall outweighs summer melt," Thompson said.

"[But] it's likely these glaciers will follow the same pattern of those in Sweden and Norway, which were growing until 1999 due to increasing winter snowfall even as temperatures rose.

"However, since 1999 these same glaciers are now retreating.

"The balance of glaciers globally shows retreat and even acceleration in the rate of retreat," Thompson stressed. (Related news: "Greenland Glaciers Losing Ice Much Faster, Study Says" [February 2006].)

It may take many years to understand climate change's lasting effects on Pakistan's glaciers.

But Archer hopes for much more immediate payoff from the recently published climate data.

"We're not entirely sure what long-term climate change trends will do," he said. "But in the meantime, [water forecasting] is a really important, immediate, practical issue."

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