Increase in snow on glaciers - Niwa

Fox Glacier. Photo / Wairarapa Times-Age

More snow fell on the top of key South Island glaciers than melted last summer, increasing the overall amount of snow at the top, the National Institute of Water and Atmospheric Research's (Niwa) annual end-of-summer survey showed.

But, there was still a general shrinking of some of the South Island's largest glaciers, snow and ice scientist Jordy Hendrikx said.

The survey found the average amount of snow which fell from autumn 2009 to the end of summer 2010 was slightly more than the amount of snow which melted on the Southern Alp glaciers over the same period.

"This small average gain helped to hold some glaciers in a steady state over the last glacier year," Dr Hendrikx said.

There was a noticeable difference between glaciers though, with more snow falling than melting in the southern and western regions, and less snow falling than melting in the northern and eastern parts of the Southern Alps.

The previous two years had more snow melt than fall at the top of the Southern Alps.

"Our monitoring is showing a general decline over the long-term and that is consistent with the obvious shrinking of some of the South Island's largest glaciers as ice melts in the glacier trunk and calves off at the terminus," he said.

Glacier monitoring started in 1977.

"A moderate El Nino developed in the tropical Pacific in spring last year. This brought more southwesterlies, with normal to below normal temperatures through last summer and into autumn this year. The overall effect was to hold snowlines in a near steady state this year," Dr Hendrikx said.

New Zealand glaciers are very sensitive to changing wind, precipitation patterns, and temperature, unlike many glaciers worldwide.

- NZPA