Natural Environment Blog

Glaciologists at Massey University have confirmed that the Tasman Glacier, in New Zealand’s South Island, is retreating at its fastest rate in recent history.

Since the 1990s, the glacier has been retreating at an average rate of 180 meters per year. This rate will likely increase to between 477 and 822 meters per year over the next 10 to 19 years.

Dr Martin Brook, lecturer in physical geography in the School of People, Environment and Planning says that the glacier’s faster retreat rate is mainly due to the fact that there is now a lake sitting right in front of the glacier.

This lake didn’t even exist back in 1973. And even as recent as 1990, the lake was very small.

The lake was formed by the glacier’s melting ice. And now, as the glacier melts, the lake becomes higher. And as the lake gets higher, it melts the glacier ice.

This will continue until the lake cannot expand any further (because of the surrounding mountains). This will take between 10 and 19 years based on current calculations.

According to Dr Brook:

The glacier followed a slow retreat phase for a while, in that a thermo-erosional notch in the ice cliff face would develop at the water line, melt back into the glacier undercutting the ice above, causing the ice to collapse into the lake.

But what is happening now is that a short foot of ice is extending out into the lake away from the ice cliff, and the glacier is now in a period of fast retreat. This is because as the water depth increases so does the speed of retreat – simply, a much larger part of the glacier is submerged and the water, even at only two degrees celcius, is still able to melt the glacier ice

Having seen Tasman Glacier with my own eyes, I find this news quite sad. OK, it may not be the most spectacular looking glacier in New Zealand but it is the largest. Although most of the world’s glaciers are retreating, not many are retreating at this rate.

The above photo is one that I took during a walk to Tasman Glacier. You can see a small part of the lake at the top of the river. If I understand correctly, the place where I took this photo may be submerged within a few years…

The above photo is one taken from the track to Mueller Hut (opposite Tasman Glacier). You can see that the glacier is covered in rock and debris. You can also see the 7 kilometer long lake that has formed in front of the glacier. This lake will be 16 kilometers long within 10 to 19 years…

According to scientists at the University of Zurich in Switzerland, if summer temperatures increase by 9 degrees Fahrenheit (5 degrees Celsius), all 5,150 glaciers in the European Alps could be gone by the year 2100.

Even if temperatures only rise by 5 degrees Fahrenheit  (3 degrees Celsius), 80 percent of these glaciers will melt away.

Now, if you think this sounds a bit alarmist, just look at what has actually happened to these glaciers over the last 160 years or so. These glaciers have shrunk so much that they now only cover half the are they did back in 1850. Even worse, the glacier recession has sped up over recent years as the global climate increases.

And don’t forget all the other glaciers around the world too! These scientists are only referring to the European Alps. Given there are glaciers in 47 countries, who knows how many of those will still be around by the end of the century!