SOURCE: Deutsche Welle
DATE: August 30, 2018
SNIP: Glaciers are not formed from frozen water but by compacted snow. The accumulation of snow at the head of the glacier is called a névé. After four to five years, it compacts and becomes part of the glacier.
When annual snowfall at the névé is greater than annual snowmelt, the glacier advances. When snow melts faster, the glacier retreats.
In the normal run of things, the Franz Josef Glacier would advance a little, and then retreat again. Many glaciers go through centuries-long cycles this way. But with the Franz Josef Glacier, the long-term trend has been retreat.
Striations, patterns on the rocks, mark the glacier’s long path through the valley. Thousands of years ago, it would have reached as far as the sea. The first photograph of Franz Josef Glacier was taken in 1867, and shows the glacier dominating the valley.
The first official mapping of the glacier took place in 1893 between then and 1983 it retreated about three kilometers, but advanced again 1.5 kilometers by 2008.
That advance has now been lost almost completely, as the glacier retreated 1.4 kilometers over the last decade. That has scientists worried. “That’s a big retreat and it’s happened really fast,” Brian Anderson, a glaciologist at Victoria University in Wellington, told DW.
Anderson has no doubt the reason for the glaciers’ retreat is anthropogenic — or man-made — climate change. “New Zealand’s glaciers are quite special and responsive to climate change, and sensitive, so they can respond really quickly and move quite a long way,” he told DW.
The Franz Josef Glacier’s three-kilometer retreat during the 20th century occurred as the Earth warmed by about 1 degree Celsius.
Guides used to be able to lead tourists straight on to the glacier by foot. Now, flying in on a helicopter is the only way for tourists to climb on the glacial ice.