Mon, 23 Nov 2009 5:22p.m.
NZ's glaciers have halved in size in the last century
By Lachlan Forsyth
On the eve of the Copenhagen climate summit, New Zealanders have been presented with dramatic evidence that we are not immune to climate change.
The country's glaciers are melting away according to a Niwa report that shows they have lost half of their snow and ice in the last century.
Scientists are warning the big glacier melt will continue.
It has long been known that the Tasman Glacier - the country's longest - is shrinking. But the latest information from Niwa shows virtually every other glacier in the country is doing likewise.
"We've seen about a 50 percent decrease in the ice volume of the Southern Alps," says Jordy Hendrikx, snow and ice scientist. "So if you were considering a health status, they've lost half of their health already."
Niwa says glacier length is misleading because total volume can be decreasing even while length is increasing. Their concerns surround the glaciers' mass balance - the snowfall required to replace the snow melt, and thereby maintain a glacier's size.
Since 1997, less snow has been falling and more ice has been melting. And since 2000, the southern glaciers have been below their tipping point - meaning that, apart from a small spike earlier this decade, the mass balance has declined sharply.
"That's a very slight warming over that time, and we're looking in the future that we're going to see continued warming and therefore continued ice loss," says Mr Hendrikx.
Worldwide it's not much better, the number of glaciers retreating now far outnumber those advancing - a huge turnaround since the late 1970s when advancing glaciers were the norm.
"The ends of our glaciers are just snapping off like chocolate and melting very rapidly, so we are losing a lot of ice mass very quickly," says climate scientist Jim Salinger.
Prime Minister John Key says he takes the demise of our glaciers seriously, just not seriously enough to attend Copenhagen himself.
"No, it doesn't prompt me to go to Copenhagen but it does show we need to take climate change seriously," he says.
Despite this, sceptics will claim there is still no evidence that climate change is caused by human activity.
"The physics of climate change are bloody obvious, which is if you put more greenhouse gases in the planet, it will warm," says Mr Salinger.
"Over the long period of time there's a clear trend that we're seeing a reduction in ice," says Mr Hendrikx. "It's undeniable that we have altered the atmosphere."
Man-made threat or not, there is no denying our famed glaciers may soon be in short supply.
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