By Julian Martin
I was taken aback last summer whilst in New Zealand, when returning to visit the Franz Josef Glacier, 14 years after I had last seen it. Only this time, I didn’t see it. The Franz Josef Glacier has both retreated and grown since 2001, but its most recent retreat of 800 meters, between 2011 and 2014, is the fastest on record.
Mid-latitude valley glaciers like Franz Josef are very sensitive to local and global climate, acting as an indicator of climatic change. Their recession, aside from ruining a perfectly good Instagram post, affects the people that rely on them for employment, contributes to sea level rise, and can teach us directly about the changing conditions of our planet.
What has been happening?
The glacier was still there, but my eyes were not deceiving me entirely. GPS data and photographic evidence collected by Brian Anderson from the University of Wellington, shows the glacier receding significantly in the space of only 15 years1.
However this is not the whole story. The retreat that began in 2001 came to a halt four years later, and the glacier began to grow again. In 2008, after just three years of growth, it was back to the length it had been when I first visited in 2001. The glacial loss that I observed last year began again in 2011. So the Franz Josef Glacier has actually receded 800 meters in just four years!
Scientists have been keeping track of the glacier’s size since the late 1800s, and this data shows that periods of advance and retreat like this aren’t uncommon. In 2014, a team led by Heather Purdie at the University of Canterbury, combined these long-term glacier records and found that the Franz Josef Glacier has in fact seen four significant periods of advance and retreat over the past 120 years1. Despite this, the overall shrinking trend is clear, with the glacier now 2.5 km shorter than it was in 1900. The nearby Fox Glacier has behaved in a similar way.
What is the cost?
The glacier tourism industry, big business in South West New Zealand, has had to adapt. Tourism is a significant part of New Zealand’s economy, bringing in around 5 billion NZ Dollars (£2.3 million) a year. Around 300,000 people visit the Westland each year, the region containing the country’s three most tourist-focused glaciers: the Fox, Tasman and Franz Josef. Traditional walking tours at Franz Josef now rely on helicopters to ferry visitors on and off the ice, as the glacier is no longer accessible from the valley floor. The result is overcrowding and increased cost to tourists. But the changes haven’t all been negative. A 2013 report by Heather Purdie shows that the lake in front of the Tasman glacier is expanding, allowing tour operators to use larger, faster boats2. This, along with the added attraction of more ice breaking off the glacier and falling into the lake, has actually seen visitor numbers increase. Despite retreat, glacier tourism in New Zealand is still thriving.
Receding glaciers are a global issue
It isn’t just the Franz Josef Glacier that’s in trouble. The Intergovernmental Panel on Climate Change (IPCC) reports that World Glacier Monitoring Service records from 500 glaciers show that glaciers are retreating globally, in spite of decadal variations, and that there is “very high confidence that globally, the mass loss from glaciers has increased since the 1960s”3.
What does the Franz Josef glacier tell us about the climate?
Studies have shown that short-term variations in glacier length are associated with large changes in ocean and atmospheric circulation, and especially with El Niño events. During such events, which occur every 2 to 7 years, warm waters develop in the eastern Pacific, and can cause changes to weather patterns across the globe. In New Zealand, stronger south westerly winds, greater precipitation in the Southern Alps, and cooler temperatures, lead to an increase in glacier mass. The opposite is the case during La Nina events, when waters in the eastern Pacific are colder than normal, and the glacier has generally undergone periods of recession.
Oscillations in glacier length occur at Franz Josef due to the glacier’s sensitivity to climatic changes, and tend to show a three to four year lag in response to short-term events like El Nino. Other glaciers, with reaction times on the scale of decades, don’t track the effects of such short-term climate change.
The long-term trends of glacier retreat reflect longer-term, global climate change, and can tell us about the effects we are having on the natural world. The most recent IPCC report states that human influences have “likely contributed to the retreat of glaciers since the 1960s”. Scientists attribute about 25% of current sea level rise (0.76 mm/yr) to the retreat of glaciers, making glacial retreat the second largest contributor to increases in sea level.
Will the glaciers grow back?
As we are currently experiencing a period of El Nino, some growth could occur at Franz Josef over the next few years, but it is unlikely to alter the long-term trend of ice loss. In a 2008 study, Brian Anderson at the University of Canterbury, New Zealand, produced a model of the glacier under a moderate climate change scenario. The model predicted a retreat of 5 km by the end of the century4.
The final icy nail in the coffin comes from IPCC data, which suggests that because of their long reaction time, even if global temperatures stabilise, glaciers will continue to shrink. Small glaciers are likely to be worst hit, and many will be lost completely.
It looks like if I want to see the Franz Josef Glacier again, I should probably go back sooner rather than later…
1. Purdie, H., Anderson, B. M., Chinn, T. J. H., Owens, I., Mackintosh, A. N., & Lawson, W. J. (2014). Franz Josef and Fox Glaciers, New Zealand: Historic length records. Global and Planetary Change, 121, 41–52. DOI: 10.1016/j.gloplacha.2014.06.008
2. Purdie, H. (n.d.). Glacier Retreat and Tourism: Insights from New Zealand. DOI: 10.1659/MRD-JOURNAL-D-12-00073.1
3. Vaughan, D.G., J.C. Comiso, I. Allison, J. Carrasco, G. Kaser, R. Kwok, P. Mote, T. Murray,
F. Paul, J. Ren, E. Rignot, O. Solomina, K. Steffen and T. Zhang, 2013: Observations: Cryosphere. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung,
A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
4. Anderson, B., Lawson, W., & Owens, I. (2008). Response of Franz Josef Glacier Ka Roimata o Hine Hukatere to climate change. Global and Planetary Change, 63(1), 23–30. DOI: 10.1016/j.gloplacha.2008.04.003