A new low for global warming:
Arctic sea ice retreats to furthest point on record
Scientists warn that neither the cause nor the consequence of today's
new record retreat for Arctic sea ice should be ignored. But with
drilling opportunities at stake, which interest will prevail?
The news that came yesterday should be, environmental campaigners
said, a global wake-up call. The ice cap covering the top of the world
is now smaller than it has been at any point since scientists started to
measure it precisely from space.
Satellite data released last night show that the sea ice floating on
the Arctic Ocean has reached a record low, retreating further than it
has done since detailed records began more than 30 years ago.
The US National Snow and Ice Data Centre in Boulder, Colorado said
that the 2007 record was broken on Sunday with two or three weeks of the
melt season still remaining, suggesting that this year's sea ice will
retreat substantially further than at any time in the satellite era. The
snow and ice centre said that the surface area of the Arctic Ocean
covered by floating sea ice fell to 4.10 million square kilometres
(1.58m square miles), which was 70,000 square kilometres below the
previous record minimum of 4.17 square kilometres set in September 2007.
This means that since 1979, when satellite readings began, the six
lowest sea-ice extents have all occurred in the past six years, from
2007 to 2012.
The sea ice retreat was particularly rapid this August and may have
been exacerbated by an intense storm over the Arctic region. However,
scientists believe that global warming caused by rising levels of carbon
dioxide in the atmosphere is the only plausible explanation for the
continued loss of Arctic sea ice, which is one of the most visible
consequences of man-made climate change.
"By itself, it's just a number, and occasionally records are going to
get set. But in the context of what's happened in the past several years
and throughout the satellite record, it's an indication that the Arctic
sea ice cover is fundamentally changing," said Walt Meier, a sea-ice
specialist at the snow and ice data centre.
"The Arctic used to be dominated by multi-year ice, or ice that
stayed around for several years. Now it's becoming more of a seasonal
ice cover and large areas are now prone to melting out in summer," Dr
Meier said.
Mark Serreze, director of the data centre, said that the previous
record set in 2007 occurred because of near-perfect summer weather for
melting sea ice, with clear skies and intense sunshine dominating the
region's weather.
"Apart from one big storm in early August, weather patterns this year
were unremarkable. The ice is so thin and weak now, it doesn't matter
how the winds blow," Professor Serreze said.
It is normal for sea ice floating on the Arctic Ocean to ebb and flow
with the seasons. It thickens and grows in the cold winter months and
melts and retreats again in the summer, reaching a seasonal minimum each
summer during early September.
However, since 1979 Arctic scientists have observed that the
September minimum is significantly smaller in terms of surface area of
the ocean covered by sea ice. This trend has accelerated in recent
years. Computer models of how the sea ice would respond to global
warming initially suggested that the region could be free of summer sea
ice by the end of the century. Later models suggested this could occur
as early as 2030 or even earlier, but none had predicted the rapidity of
the observed loss of sea ice.Sea ice is seen as important because of its
disappearance could lead to other important changes to the Arctic
environment. One immediate effect is the opening up of shipping lanes
that could lead to new oil and gas explorations within the region,
triggering political tensions as well as further releases of carbon
dioxide from the mining and burning of fossil fuel.
The record minimum was announced just two days after the Royal Dutch
Shell's drilling ship, the Noble Discoverer, took advantage of reduced
sea ice and started sailing from Alaska to the Chukchi Sea, in
anticipation of final US government approval for oil exploration in the
region.
Scientists have already observed a link between disappearing sea ice
and the release of methane, a greenhouse gas that is more than 20 times
more potent than carbon dioxide, from beneath the Arctic Ocean.
Researchers flying over the melting sea ice reported last May that
significant quantities of methane are being released from between the
cracks in the ice.
"When we flew over completely solid sea ice, we didn't see anything
in terms of methane. But when we flew over areas were the sea ice had
melted, or where there were cracks in the ice, we saw the methane levels
increase," said Eric Kort, of Nasa's Jet Propulsion Laboratory in
Pasadena, California.. "We were surprised to see these enhanced methane
levels at these high latitudes. Our observations really point to the
ocean surface as the source, which is not what we had expected," he
said.
Other scientists have observed huge plumes of methane being released
from beneath the permafrost of the East Siberian Arctic Shelf off
northern Russia.
The Arctic is known to have huge stores of trapped methane in the
form of gas hydrates, which some experts fear may be released if Arctic
permafrost continues to melt. John Sauven, executive director of
Greenpeace, said that the latest data on how fast the sea ice is in
retreat should be a warning to the world.
"Let's be clear about what today means - our planet is warming up at
a rate that puts billions of people's future in jeopardy," Dr Sauven
said.
"These figures are the effects of man-made global warming caused by
our reliance on dirty fossil fuels," he said.
- The Independent
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