Global Warming Continues To Accelerate Unabated

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Thu, 11 Aug 2005 23:07:55 -0700

Global Warming Continues To Accelerate Unabated

 

 

 

Global Warming Continues To Accelerate Unabated

 

 

 

Climate Warning as Siberia Melts

By Fred Pearce

NewScientist.com

 

Thursday 11 August 2005

 

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.

 

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.

 

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