Climate warning as Siberia melts
by Fred Pearce
11 August 2005

http://www.newscientist.com/article....mg18725124.500

THE world's largest frozen peat bog is melting. An area stretching
for a million square kilometres across the permafrost of western
Siberia is turning into a mass of shallow lakes as the ground melts,
according to Russian researchers just back from the region.

The sudden melting of a bog the size of France and Germany combined
could unleash billions of tonnes of methane, a potent greenhouse gas,
into the atmosphere.

The news of the dramatic transformation of one of the world's least
visited landscapes comes from Sergei Kirpotin, a botanist at Tomsk
State University, Russia, and Judith Marquand at the University of
Oxford.

Kirpotin describes an "ecological landslide that is probably
irreversible and is undoubtedly connected to climatic warming". He
says that the entire western Siberian sub-Arctic region has begun to
melt, and this "has all happened in the last three or four years".

What was until recently a featureless expanse of frozen peat is
turning into a watery landscape of lakes, some more than a kilometre
across. Kirpotin suspects that some unknown critical threshold has
been crossed, triggering the melting.

Western Siberia has warmed faster than almost anywhere else on the
planet, with an increase in average temperatures of some 3 °C in the
last 40 years. The warming is believed to be a combination of
man-made climate change, a cyclical change in atmospheric circulation
known as the Arctic oscillation, plus feedbacks caused by melting
ice, which exposes bare ground and ocean. These absorb more solar
heat than white ice and snow.

Similar warming has also been taking place in Alaska: earlier this
summer Jon Pelletier of the University of Arizona in Tucson reported
a major expansion of lakes on the North Slope fringing the Arctic
Ocean.

The findings from western Siberia follow a report two months ago that
thousands of lakes in eastern Siberia have disappeared in the last 30
years, also because of climate change (New Scientist, 11 June, p 16).
This apparent contradiction arises because the two events represent
opposite end of the same process, known as thermokarsk.

In this process, rising air temperatures first create "frost-heave",
which turns the flat permafrost into a series of hollows and hummocks
known as salsas. Then as the permafrost begins to melt, water
collects on the surface, forming ponds that are prevented from
draining away by the frozen bog beneath. The ponds coalesce into ever
larger lakes until, finally, the last permafrost melts and the lakes
drain away underground.
“This is an ecological landslide that is probably irreversible and is
undoubtedly connected to climatic warming”

Siberia's peat bogs formed around 11,000 years ago at the end of the
last ice age. Since then they have been generating methane, most of
which has been trapped within the permafrost, and sometimes deeper in
ice-like structures known as clathrates. Larry Smith of the
University of California, Los Angeles, estimates that the west
Siberian bog alone contains some 70 billion tonnes of methane, a
quarter of all the methane stored on the land surface worldwide.

His colleague Karen Frey says if the bogs dry out as they warm, the
methane will oxidise and escape into the air as carbon dioxide. But
if the bogs remain wet, as is the case in western Siberia today, then
the methane will be released straight into the atmosphere. Methane is
20 times as potent a greenhouse gas as carbon dioxide.

In May this year, Katey Walter of the University of Alaska Fairbanks
told a meeting in Washington of the Arctic Research Consortium of the
US that she had found methane hotspots in eastern Siberia, where the
gas was bubbling from thawing permafrost so fast it was preventing
the surface from freezing, even in the midst of winter.

An international research partnership known as the Global Carbon
Project earlier this year identified melting permafrost as a major
source of feedbacks that could accelerate climate change by releasing
greenhouse gases into the atmosphere. "Several hundred billion tonnes
of carbon could be released," said the project's chief scientist, Pep
Canadell of the CSIRO Division of Marine and Atmospheric Research in
Canberra, Australia.

>From issue 2512 of New Scientist magazine, 11 August 2005, page 12