Siberia faces meltdown

The Climate and Land Surface Systems Interaction Centre at the University of Leicester hosted an international scientific Symposium on “Environmental change in Siberia – Insights from Earth Observation and modelling” from 18-20 September 2006. Around 30 participating scientists from the UK, Russia, Austria, France, Italy and Germany presented new findings on the rapidly occurring environmental changes in the vast Siberian forest tracts. The Symposium brought together leading scientists from different disciplines who have been developing new information systems based on satellites, field data and climate models.

University of Leicester’s Professor Heiko Balzter, who has studied satellite images of Siberia for the past eight years, said: “Siberia is a hotspot in the global climate system. Because the Siberian ecosystems are largely temperature controlled the region is strongly affected by global warming. Large amounts of greenhouse gases are currently locked in the permafrost and in organic soils, and if released could accelerate the greenhouse effect.”

According to the latest meteorological data, Siberia seems to warm up even faster than previously predicted by the Hadley Centre climate model. The warming trend affects mainly the winter months and leads to an earlier snow melt. The resulting earlier onset of spring can be detected from a range of satellites, and is believed to be advancing by as much as 0.5 to 1 day per year since satellite observations began in 1982.

Russian scientist Dr Tchebakova reported that rainfall in Central Siberia has decreased over the last 30 years. Together with the measured higher temperatures this increases the risk of catastrophic forest fires. To get better estimates of carbon emissions, Professor Wooster from Kings College London has been measuring the heat released from forest fires. But not only do fires release greenhouse gases while they burn. Dr Le Toan from Toulouse presented model results which strongly suggest that burned forest areas release greenhouse gases into the air for up to 30 years after a fire.

Dr Petko from the Forest Institute in Krasnoyarsk told the Symposium that just two consecutive dry and hot summers can trigger large outbreaks of the Siberian moth. This tiny insect can eat the needles of entire forest regions, hundreds of thousands of hectares in one summer. The remaining dead trees dry out and are extremely susceptible to forest fires, which are easily caused by lightning and also humans. About 80% of insect infested areas catch fire at some point over the following 5-10 years. This risk prompted Russian scientists to develop a pheromone trap, which attracts male moths. The new traps make moth monitoring significantly more efficient than the previous method which relied on shaking of trees and the counting of the larvae fallen to the ground.

Dr Tchebakova from Krasnoyarsk told the symposium that under one of the climate scenarios developed by the Hadley Centre in the UK, the current boreal forest zone could be so dried out by 2090 that the trees would die off and be replaced with steppe. As a consequence, the Arctic would warm so much that trees could grow at the shores of the Arctic Ocean in Northern Siberia, currently an arctic desert. This is not as far-fetched as it might appear: Dr Melvin from the UK’s Climate Research Unit observed prehistoric tree stumps in the Siberian arctic region during a field trip, so another dramatic shift of plant communities is not unthinkable. First strange observations of Russian trees have already been made by Vienna based scientists Dr McCallum and Professor Shvidenko. They found that Siberian trees have changed the proportion of roots, branches and stem wood over the last 60 years. It is yet unclear whether this is due to climate change. Because the forest is the basis for local people’s lives in the region, its retreat to the north could trigger a large scale human migration.

The Siberian land mass has a profound impact on the climate in the Northern Hemisphere, and large-scale changes like the melting of permafrost or an increase in extreme forest fire years could potentially accelerate global climate change. The Director of the Centre for Terrestrial Carbon Dynamics, Professor Quegan, stressed the important role of the Siberian vegetation which currently takes up carbon from the atmosphere. This was reinforced by Dr Monks from the University of Leicester when he showed satellite images of the atmosphere illustrating how carbon is being soaked up by the forest during summer. The current moderate carbon sink in Siberia could change to a source of greenhouse gases if a tipping point in the regional climate was reached.

Professor Balzter pointed out how successful the collaboration between UK, European and Russian scientists has proved. Professor Schmullius, who has coordinated two previous international research projects on Siberia, said “With the support of the European Commission, many of these scientists have worked together in previous research, like the SIBERIA project, which has mapped about 10 million hectares of forest at an unprecedented 50 m spatial resolution. Many were also involved in the SIBERIA-2 project, which created the first full greenhouse gas accounting scheme of the terrestrial biosphere from a combined satellite remote sensing and vegetation modelling approach.”

The Climate and Land Surface Systems Interaction Centre operates a Visiting Scientist Scheme. It has funded a previous research visit by Russian scientist Dr Onuchin to the UK in 2005, and is going to invite Dr Ponomarev in 2007 to work on forest fires at the University of Leicester.

Professor Balzter concluded “The participants of the Symposium gave me a very strong message that further internationally coordinated research is needed to reduce the remaining uncertainties in the role of environmental changes in Siberia in the global climate system. Siberia is an important building block in the Earth system.”