Glaciers gain ice mass in past year 17 August 2004

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The 50 Southern Alps glaciers monitored annually by NIWA gained ice mass in the past year.

NIWA Senior Climate Scientist Dr Jim Salinger said today that after analysis of photographs taken on the survey of the glaciers in March this year it was apparent they had gained much more ice than they had lost during the past glacier year.

This is because much more snow fell in the Southern Alps over the spring and summer period as a result of more frequent cool and stormy conditions. During this 6-month period more depressions (‘lows’) over southern New Zealand and to the south produced frequent episodes of strong cold westerly winds. For the September 2003 to February 2004 half year, temperatures were 0.5°C below average and precipitation between 30 and 50 percent (one and a third to one and a half) times more than normal. These conditions produced more snow precipitation, especially in spring, and the cooler than normal summer resulted in markedly less snowmelt.

“The last two glacier years’ (2002/03 and 2003/04) gains have, for a short term, halted the declines seen since 1998 in which the glaciers have lost ice mass. The gains over the past two years rank the seventh and ninth highest respectively since records commenced in 1977.”

He said the surveys had been carried out every year for the past 27 years, and they clearly showed that the gains in ice mass in 2002/03 and 2003/04 in glaciers such as the Fox and Franz Josef may reverse the recent trend for them to shrink.

Dr Salinger said the annual NIWA flights in March use a small fixed wing aircraft. They record the height of the glaciers snow line at the end of summer.

“This reveals how much snow the glaciers have lost or gained during the past year. The lower the snow line, the more the amount of snow that has accumulated to feed the glacier. On average the snowline this year was about 85 metres below where it would be to keep the ice mass constant.”

He said the level of the glacier snow lines was unrelated to the amount of snow that might fall on the country’s ski fields during winter.

Change in glacier ice mass

Trends upwards represent growth in glacier ice mass and downwards loss in ice mass.

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