Science Articles

International Polar Year 2007-9

Sat, 1st Dec 2007

Britain and China collaborate on climate change studies in the Arctic

Anne Hinton

International Polar Years commenced in 1882-3, as the inspiration of Austrian explorer and naval officer Lieutenant Karl Weyprecht, a scientist and co-leader of the Austro-Hungarian Polar Expedition of 1872-74. International Polar YearThey act as a means of bringing together scientists from around the world in a concentrated effort to further studies of the Arctic and Antarctic regions. The third such 'year' runs from 2007-9. One recent development is extending China's involvement in polar studies.

Japan has long been associated with international collaborative work at the extremes of the globe. Indeed, Japanese Professor Atsumu Ohmura (an academic at ETH, in Zürich, Switzerland) is currently President of the International Glaciological Society, which is based in Cambridge, U.K. However, China, has only recently come into the picture in terms of research in polar regions.

As part of the lead-up to the International Polar Year, a Sino-British meeting was organised in Shanghai in October 2005, with the aim of assisting the development of collaborative links between Chinese and British scientists in both the Arctic and Antarctic. Sponsored by the British Antarctic Survey, The British Consulate General (Shanghai) and the Polar Research Institute of China, the conference was attended by about 60 delegates from universities and research organisations from both countries.

Dr Ian Willis, a glaciologist at the Scott Polar Research Institute, University of Cambridge was one of the British scientists who attended the meeting in Shanghai. Dr Willis explained that there has been a long tradition of training glaciologists in China, but that much of this had been concered with long-term monitoring of small glaciers with regard to water supplies for irrigation in western China, and much of the work has been published in Chinese. However, Chinese students and researchers are increasingly collaborating on international science projects with institutions outside China.

"The Chinese wish to have a stake in key international scientific research and have recognised the vital importance of the polar regions for studies of climate change", said Dr Willis. "The polar regions are especially sensitive to climate change. They have undergone greater than average global warming over the last 50 years, and climate models predict that they will exceed global average warming rates in the future. In order to assess what effect these changes will have on glaciers and ice sheets, and the consequences for sea-level rise, we need to understand climate controls on snowfall and snow and ice melt, plus the temperatures within and at the base of the ice. This is important because the ice temperature and pressure of water beneath ice masses control how fast they move."

Chinese aim for world's longest ice core in Antarctica The Chinese have established bases in Antarctica during the last two decades, and have invested some US$100 million in a variety of projects concerning Antarctica, within China and elsewhere, according to the China Daily. However, the Chinese now have very ambitious aims for their work in Antarctica and have recently built a new base in the Australian sector (as China has no claim of its own in the continent) to largely replace their two previous ones, which were suffering from corrosion. Their plans include drilling a large ice core at Dome A (or 'Argus') in the eastern part of the continent, the top of which is over 4 km above sea level.

This has the potential to provide the longest ice core record of climate and environmental change from Antarctica that has ever been achieved, if the logistical challenges can be overcome. The Chinese have already visited Dome A, undertaken some preliminary geophysical measurements in the area, and deployed an Automatic Weather Station, which recorded an air temperature of -82.5°C during 2005!

Chinese interested in the Arctic too

Another key location for polar researchers is the international research settlement of Ny-ĺlesund in the Norwegian Arctic territory of Svalbard, 60% of the area of which is ice covered. (Best known to British people is the largest island of Svalbard - Spitsbergen). There are many international science bases in Ny-ĺlesund, including some from Asian countries. The Koreans established a foothold there a number of years ago and the Chinese have just followed suit. Ny-ĺlesund is geared up for international collaborative research, with all the international research bases within the one settlement, so is an ideal place to act as a base for Chinese involvement in international Arctic science.

Dr Willis has been working in Svalbard, out of Ny-ĺlesund, in collaboration with British and Norwegian scientists (including Dr David Rippin, University of Hull, and Dr Jack Kohler, Norwegian Polar Research Institute), for the last eight years. Subsequent to the meeting in Shanghai, his work has been extended to include collaboration with Chinese glaciologists working on Svalbard. Dr Willis' recent studies have concentrated on the glacier Midre Lovénbreen, where he is examining the changing volume, temperature distribution, hydrology and dynamics of the glacier. The glacier that the Chinese are interested in, Austre Lovénbreen, is the one next door. Dr Jiawen Ren (Chinese Academy of Sciences) and Dr Ming Yan (Polar Research Institute of China) have just established a monitoring programme on the glacier and Dr Willis' team has undertaken the first radar survey to determine the overall geometry and thermal regime of the glacier. Repeating this work in the future will enable an examination of how the glacier is responding to climate change.

Signficance of Svalbard glaciers for climate change

Small glaciers represent only a tiny fraction (about 4%) of total land ice, but are generally much more sensitive to climate change than the big ice sheets of Antarctica and Greenland and have contributed about 25% of the total amount of sea-level change during the last century, and there have been suggestions that their relative contribution to sea-level change is increasing. The reason that the Svalbard glaciers are so important is that they are 'polythermal'.

Glaciers and how they work

Many glaciers are either entirely 'warm' or entirely 'cold', but those in Svalbard tend to be a mixture of both: 'polythermal'. The temperature of the ice at the base of the glacier determines whether water is present or not. On Svalbard, where the mean annual air temperature is below 0°C, glacier ice tends to be below 0°C too. However, where the ice is thick, the energy supplied to the base of the glacier, e.g. by friction as the ice deforms and flows, cannot be conducted up through the glacier to the surface so the basal ice warms up; if it reaches 0°C water will then form. Where the ice is thin, energy can easily be conducted through the ice and the glacier will remain frozen to its bed.

A glacier 'flows' by the downward force of gravity acting on the ice to create movement between the individual ice crystals. "The temperature of the ice controls the rate at which this occurs", explained Dr Willis. "You know it's easier to pour honey from a jar if it's warm rather than cold; well it's the same for ice." Warm-based glaciers are also able to move at their base due to the lubricating effects of water.

Many glaciers on Svalbard are polythermal with a warm-based central area, where the ice is thick, and a cold-based margin where the ice is thin. Water, produced by melting in summer, builds up beneath the warm-based core, and is trapped behind the cold-based margin. As water pressures rise, a connection is forced through the cold-based margin and water runs out from the glacier. "This process has important implcations for the delivery of freshwater, nutrients and sediments to the Svalbard fjords, which in turn impacts on the ecosystems there. It also has important implications for the speed at which the glacier moves, since high water pressures at the base of an ice mass promote rapid motion", pointed out Dr Willis.

Anglo-Chinese research in Svalbard

Whilst in Svalbard last April, Dr Willis and his co-researchers, from Britain and Norway, carried out Ground-Penetrating Radar (GPR) studies of both Midre Lovénbreen and Austre Lovénbreen. The work on Austre Lovénbreen was carried out as a direct consequence of the Chinese interest in that glacier.

GPR is a technique by which a radio wave is transmitted into the ground. At each major discontinuity beneath the surface, a signal is reflected back to the receiving antenna on the surface. Major discontinuities in glacial ice include:

i) layers of ice with different characteristics which may represent annual layers of winter snow which have gradually turned to ice;

ii) large tunnels within the ice;

iii) the boundary between cold and warm ice; and

iv) the boundary between the bottom of the glacier and the underlying bed.

Dr Willis' team are especially interested in mapping the latter two discontinuities.

GPR measurements are usually made along transects that criss cross the glacier surface from side to side, and along its length. At the same time, a Global Positioning System (GPS) is used to calculate the location of the GPR. In this way, the depth of the glacier, together with the thickness of cold and warm ice, can be determined. The setup - with the GPR transmitter and receiver and the GPS - is towed on sledges behind a skidoo.

Dramatic changes to the Svalbard glaciers

The research that Dr Willis and colleagues are doing, which is being published in international science journals such as the Journal of Glaciology, shows that over the last three decades Midre Lovénbreen has reduced in both size and volume. Since 1977, the glacier has retreated about 300m at its leading edge (the 'snout'), its area has reduced by about 600,000 m2 (about 11% of its 1997 area) and its volume has dropped by about 64 million m3 (about 17% of its 1977 volume). "This is equivalent to about 20,000 olympic swimming pools of water, or enough water to fill the Royal Albert Hall about 600 times over", explained Dr Willis. "The GPR measurements also show that, as the glacier has shrunk, it has become increasingly cold-based."

"While the snout has retreated around 200m since 1990, the boundary between the warm- and cold-based parts of the glacier has retreated around 1300m. In 1990, the cold-based margin was around 400m from the snout but now it's about 1500m from the snout. This is a much bigger change in the thermal characteristics of the glacier than we were expecting", said Dr Willis.

The implications are that, as Svalbard polythermal glaciers shrink due to climate change, water that collects beneath the warm-based core may find it increasingly difficult to escape through the cold-based ice margin. When water does escape from beneath the ice the floods may be more dramatic than they were. Initially, as the glaciers thin and more and more of their area becomes frozen to the bed, they may slow down. However, in the longer term, if air tempertatures continue to rise, they may speed up again.

"Ultimately we want to know what all the ice on Svalbard is doing. We can't simply extrapolate from one glacier to the next. We need to understand the general physical processes happening, and apply that understanding via physics-based computer models to other areas and into the future", said Dr Willis. Continued collaboration with other researchers, more field data and the development of more sophisticated computer models are key to extending the dataset and making predictions about future changes.

Polar Bears

And, yes, one of the potential hazards of work in this area, apart from the cold, is polar bears. "Unfortunately I have never seen one", said Dr Willis, "but each year a polar bear is usually seen strolling through Ny-ĺlesund at some stage". A rifle is loaded on leaving Ny-ĺlesund each day, and unloaded on return, solely for self-protection in case of need; it is illegal to shoot a polar bear for any other reason. Carrying a rifle for self-protection is a requirement for all scientists working on Svalbard. But the danger is far outweighed by the importance of the location for scientific research, and the beauty of the Arctic scenery.

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