EDIT
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.
EDIT
http://www.innovations-report.de/html/berichte/umwelt_naturschutz/bericht-70982.html
Printer-friendly format
Email this thread to a friend
Bookmark this thread
(1000+ posts)
Send PM |
Profile |
Ignore
