Study highlights impact of climate change on Arctic river systems
Climate change is already having a major impact on one of the longest rivers in the world, the 4,400 kilometre Lena, which flows from south to north through Central Siberia to the Arctic Ocean. The work, which was carried out by French, Russian and American scientists in the framework of the International Polar Year (IPY), is published in the journal Geophysical Research Letters. In Central Siberia the temperature can fall to as low as -70°C and the permafrost is 1.5 km thick. During the last four decades alone, the air temperature in winter has risen by 4°C, while the river's spring temperature has increased by 2°C since the 1980s. In this study, the scientists, led by France's National Scientific Research Centre (CNRS), looked at data, including photographs, satellite images and ground data, going back to the 1960s to see how these temperature increases had affected the river. They found that more of the upper layer of permafrost was melting every year, and this melt water was flowing into the Lena. This increased the amount of water in the river, which in turn caused greater erosion of the banks. This erosion poses a serious threat to the urban centres and industrial installations situated along the river. Furthermore, the increased water flow also affects the islands in the river. The heads of these islands, which bear the brunt of the river's strength, are eroding faster. As a consequence, greater quantities of sediment are being moved around the river, where they form sandbanks. In some cases, these sandbanks have rendered certain channels impassable for shipping. In winter, the river freezes over and lorries use it as if it were a motorway. However, the study also revealed that this winter ice is getting thinner and thinner, and it is unclear how much longer the ice will be able to bear the weight of a lorry. This is a major problem for the region's economy, as the river forms a key route for the export of both raw materials and finished products out of the region. 'This suggests that recent global warming directly affects the fluvial dynamics and the erosional process of one of the largest arctic fluvial systems,' the researchers conclude.
Countries
France, Russia, United States