THE MODERN MELT
New Zealanders born today will live to see their country’s great glaciers shrink into extinction. In the first of a three-part series, Stuff national correspondent Charlie Mitchell explains the alarming retreat of Franz Josef and Fox glaciers.
On the gentle, stony path that weaves through rain forest at the base of the Southern Alps, a red arrow on a large sign points to the ground and says: ‘Here is where it used to be’.
There are more signs along the path. Once, it was here, and then it was here. This is a historical timeline, beginning hundreds of years ago and moving into the recent past, through podocarp rainforest and Ra¯ ta¯ trees, trees that get younger and younger until you reach the viewing platform where the timeline ends with a grey and distant glacier, recoiling up a valley.
There are hundreds of thousands of glaciers in the world, but Franz Josef is special, largely because of the path that leads to it. The glacier starts high in the Southern Alps with a heavy, inaccessible snowfield, but drops steeply into a valley a few hundred metres above sea-level, ending with a braided river flowing beside rain forest to the ocean.
Like glaciers all over the world, the modern story of Franz Josef is one of decline. During the last ice age, it surged many kilometres further in a glistening wall of ice. By the time it was found and named by colonial settlers in the mid-19th century, it reached where the first viewing platform is today. Now, it is several kilometres further back, high up a valley, its tongue decapitated.
The irony is that although Franz Josef glacier is likely the smallest it has been for many thousands of years, it has never been in higher demand. Tourism has boomed to an unprecedented level, largely through a buoyant Chinese tourism industry – in the summer months, the entire town is booked out. The township must grow to meet that demand.
It risks, quite literally, building onto thin ice. The glacier will continue to shrink, likely at a rapid pace as the world gets warmer. Even if the world stopped polluting the climate today, the retreat would not stop, although it would probably slow. There will come a time where Franz Josef will no longer be spectacular, at least from ground level, and visitors will stop coming.
It’s a long term threat to those who live and work in Glacier Country, the engine room of the West Coast economy which has spawned a multi-million dollar industry, employing hundreds of people. But for now, business is booming. The ice remains.
A few days earlier, ex-tropical cyclone Fehi had landed on the West Coast, destroying roads and flattening buildings in Glacier Country. But nevertheless, the path to Franz Josef glacier is packed. The car park is straining with rented campervans and tour buses, their colourful slogans popping in the grey valley.
After a 15 minute walk through the forest, the glacier first comes into view with a viewing platform hanging over the riverplain below. There are young families and tour groups and grandparents with their grandchildren, some from China, others from Germany, Australia, the United States.
An older German couple, Edeltraud and Wolfgang Mueller, have perched in a spot among the crowd.
Wolfgang was last here as a young man 48 years ago, he says, when the glacier roared down the valley, near where he is standing now.
It is much smaller now: ‘‘It looks completely different,’’ he says. ‘‘I expected that’’.
Edeltraud, visiting for the first time, does not mind how the glacier has withered, but sees it as a warning.
‘‘Twenty or 30 years ago, we thought about climate change and everybody said ‘oh, you’re silly’,’’ she says. ‘‘But now we have it, it’s right here.’’
We know climate change influences massive storms and rising seas, acidifies the oceans and kills forests; we know it can increase the range of diseases, while reducing the range of rare species. But when we see those things, they can seem one step removed from the process of warming.
A glacier is useful because it is simple.
The way it sheds ice in chunks and leaks meltwater through its tongue, how it slowly retracts into the mountains, taps into a basic truth that everyone knows: Ice melts in heat.
‘‘I think they’re the most valuable measure of climate change,’’ says Dr Trevor Chinn, a glaciologist.
‘‘Every single item to do with climate is fed into them.’’
New Zealand’s best-known glaciers are steep, accessible, and warm, due to the maritime climate of a land surrounded by ocean, which makes them susceptible to minor temperature changes.
All glaciers have a ‘‘response time’’, which is how long it takes for the glacier to respond to temperature changes.
For many large glaciers, it’s a couple of decades; larger glaciers can have response times as long as a century.
Franz’s response time is only three or four years, and Fox’s is five or six years, which means we can see how they’re being affected by today’s climate.
‘‘The ice in the glacier is only just below zero degrees, so if you think about that, you don’t have to change temperature very much to bring it up to melting,’’ says Dr Heather Purdie, a glaciologist at the University of Canterbury.
‘‘And [glaciers] are not just measuring temperature, they’re measuring precipitation, snow, cloudiness – all these other general climate parameters are homogenised into the glacier, and it’s providing an average picture of regional climate for the area that it’s in.
By following the shifts in the glacier, we can see what the slow burning climate signals are unable to tell us: What we are doing is transforming the natural world, which is changing in front of us.
‘‘I think they’re the most valuable measure of climate change.’’
Glaciologist Dr Trevor Chinn