|Franz Josef Glacier 2009 - Julian Thomson GNS Science|
|Franz Josef 2009- Photo Eric Burger|
In 2009 the glacier filled the head of the valley with its spectacular ice falls. It was easy to walk onto the glacier with the appropriate equipment - crampons and ice axe.
|Franz Josef 2014- Julian Thomson, GNS Science|
2014 - a big difference! The ice is now no longer apparent on the floor of the main valley, and only the distant ice of the upper ice fall can be seen. The glacier terminus has melted back by about 500 metres.
Some of the boulders are smoothed and rounded, having been dragged along at the base of the glacier before being dumped where the ice melted.
Huge jagged boulders like this one will have fallen onto the surface of the glacier from the adjacent cliffs. They have not been smoothed by any scraping action along the bed of the glacier.
This ridge of boulders running from the foreground into the centre distance of the image is one of several small terminal moraines left recently by the retreating ice. The glacier is now away to the left of the image.
Is this a view of the long term future of Franz Josef, or will this barren pile of debris be over-ridden again by the glacier again sometime soon?
To explore this question further we need to understand a bit about the dynamics of a glacier. (For more in depth information about processes of glacier formation have a look at our GNS glacier page here.) On top of a general understanding, we also have to consider some of the unique characteristics of Franz Josef glacier, and its sister, the Fox.
|Measuring summer melting at Franz Josef 2009|
|Franz Neve, Julian Thomson GNS Science|
|Lloyd Homer GNS Science|
From 1890 to about 1980 the Franz has retreated by over 3.5 kilometres, interspersed with 3 or 4 re-advances of several hundred metres lasting roughly 10 years each.
However, from about 1980 to 2000, there was a more substantial re-advance of 1.5 kilometres. This has been associated with regionally wetter and cooler conditions brought about by a phase of more El Nino conditions. These in turn relate to a fluctuating climate cycle called the Inter-decadal Pacific Oscillation. However, while the Franz and Fox were re-advancing, other glaciers in the Southern Alps with longer response times,continued to lose ice as they were (and are) still responding to the general warming of the 20th Century.
|Mount Cook and Hooker Valley, J. Thomson GNS Science|
An excellent information leaflet about the Franz and Fox glaciers is available from GNS Science:
Franz Josef Glacier features on our GeoTrips website, in case you want to go there: www.geotrips.org.nz/trip.html?id=245