The Tibetan Plateau is the highest and most extensive highlands in the world. The great Asian rivers all have their origins on the plateau or in the neighbouring mountains, and what happens on the plateau affects water resources for almost a third of the world’s population.
Professor Deliang Chen leads the Regional Climate Group at the University of Gothenburg studying climate change in Tibet, among other things. With Chinese scientists from the Institute of Tibetan Plateau Research at the Chinese Academy of Sciences, the group has studied the impact of climate change on the water balance in the region. In a joint study published late last year, researchers demonstrated that the flow of water in rivers during the coming decades will either remain stable or increase compared with the 1971-2000 period. The result runs counter to apprehensions expressed in the 2007 climate report by the Intergovernmental Panel on Climate Change (IPCC) and elsewhere that the glaciers would disappear by 2035 and water supplies in major Asian rivers would decline.
‘This is good news’, says Professor Chen, ‘because social and economic development in the surrounding areas, including China, India, Nepal and other countries in South East Asia, is highly dependent on climate and water supplies. But the fact that glaciers in the region are shrinking can become a concern in the long term, and we must keep a close watch over what’s happening with global warming.’
He has been very active in the Third Pole Environment (TPE) international research programme that coordinates research on Tibet in 15 countries. Recently, Chen and some of the world’s foremost scientists led efforts that culminated in a 10-year research plan for the region.
‘There is still considerable uncertainty about the future of the glaciers, since our understanding of meteorological and hydrological processes that are important for regional climate and the water balance of rivers is very limited. So long-range international cooperation is needed to tackle the challenge.’
Another researcher who has chosen Tibet as his area of research is geomorphologist Jakob Heyman, whose interest in Tibet was aroused when he was still a doctoral student in Stockholm. Unlike his colleagues who are studying Tibet to predict tomorrow’s climate, Heyman is primarily interested in how the Tibetan Plateau looked in the past.
‘The results show that the glaciers were not much larger than today during the last 15,000 to 100,000 years, which is a big difference compared to here in Northern Europe, which was covered by ice during the last ice age’, he says.
One of the reasons for this could be the dry climate. Although the area has been colder, it has not received more snow. Another explanation is the so-called sublimation that occurs at the extreme conditions that exist, which means that the ice does not melt and become water but instead turns directly into water vapour.
In his research, Heyman uses a special dating method called cosmogenic dating. When a rock surface is exposed to cosmic rays, cosmogenic nuclides (isotopes) form in the uppermost layer of rock and a few metres down. By measuring the incredibly small quantities of these nuclides in quartz, it is possible to calculate how long the rock formation has been subjected to cosmic radiation, or if it has been buried under ice instead.
‘Much of the work involves compiling large amounts of data’, says Heyman, who has visited the Tibetan Plateau on seven occasions.
During the early 1990s, researchers took a long ice core from a plateau glacier in north-western Tibet that goes back in time 130,000 years. And recently research teams from the United States and China have obtained two new ice cores from the same glacier to collect more data.
‘With good data, we hope we can find out what happened further back in time, and I am hoping to work more with the northern part in the future.’