Siberian forest fires trip more warming

Prof Balzter said "Last century a typical forest in Siberia had about 100
years after a fire to recover before it burned again. But new observations
by Russian scientist Dr Vyacheslav Kharuk have shown that fire now returns
more frequently, about every 65 years. At the same time annual temperatures
in Siberia have risen by almost two degrees Celsius, about twice as fast as
the global average. And since 1990 the warming of Siberia has become even
faster than before."

"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," said Prof Balzter. "Large amounts of greenhouse
gases are currently locked in the permafrost and in organic soils, and if
released could accelerate the greenhouse effect."

For the study, the scientists observed 18 years of satellite images of the
region, and estimated the timing of the onset and end of the growing season,
when the snow has melted and the plants take up carbon from the air during
plant growth.

>From 1982 to 1999 almost all Siberian ecosystems showed an earlier onset of
spring, ranging from around three days per decade to six days. "Central
Siberia has a more continental climate. The changes in the timing of spring
and also in fire occurrence are linked to temperature changes," said Prof

Global climate patterns also contribute — notably a warming of waters in
the Pacific off the coast of South America, called El Niño, and a pattern of
atmospheric pressure in the Arctic called the Arctic Oscillation, linked to
the north Atlantic. "Towards the East Siberian coast the Pacific plays a
more important role, and the El Niño phenomenon together with low rainfall
determines what happens to the forest".

Under one of the climate scenarios developed by the Hadley Centre of the Met
Office, the current forest zone in western Siberia — the largest unbroken
tract of trees on the planet — 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.

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