Global warming 'past the point of no return'
By Steve Connor, Science Editor
Published: 16 September 2005
The Independent Online Edition
(Online Article Here)
A record loss of sea ice in the Arctic this summer has convinced scientists that the northern hemisphere may
have crossed a critical threshold beyond which the climate may never recover. Scientists fear that the
Arctic has now entered an irreversible phase of warming which will accelerate the loss of the polar
sea ice that has helped to keep the climate stable for thousands of years.
They believe global warming is melting Arctic ice so rapidly that the region is beginning to absorb more
heat from the sun, causing the ice to melt still further and so reinforcing a vicious cycle of melting
The greatest fear is that the Arctic has reached a "tipping point" beyond which nothing can reverse the
continual loss of sea ice and with it the massive land glaciers of Greenland, which will raise sea levels
Satellites monitoring the Arctic have found that the extent of the sea ice this August has reached its
lowest monthly point on record, dipping an unprecedented 18.2 per cent below the long-term
Experts believe that such a loss of Arctic sea ice in summer has not occurred in hundreds and possibly
thousands of years. It is the fourth year in a row that the sea ice in August has fallen below the
monthly downward trend - a clear sign that melting has accelerated.
Scientists are now preparing to report a record loss of Arctic sea ice for September, when the surface area
covered by the ice traditionally reaches its minimum extent at the end of the summer melting period.
Sea ice naturally melts in summer and reforms in winter but for the first time on record this annual
rebound did not occur last winter when the ice of the Arctic failed to recover significantly.
Arctic specialists at the US National Snow and Ice Data Centre at Colorado University, who have
documented the gradual loss of polar sea ice since 1978, believe that a more dramatic melt began about
four years ago.
In September 2002 the sea ice coverage of the Arctic reached its lowest level in recorded history. Such
lows have normally been followed the next year by a rebound to more normal levels, but this did not occur
in the summers of either 2003 or 2004. This summer has been even worse. The surface area covered by sea ice
was at a record monthly minimum for each of the summer months - June, July and now August.
Scientists analysing the latest satellite data for September - the traditional minimum extent for each
summer - are preparing to announce a significant shift in the stability of the Arctic sea ice, the northern
hemisphere's major "heat sink" that moderates climatic extremes.
"The changes we've seen in the Arctic over the past few decades are nothing short of remarkable," said
Mark Serreze, one of the scientists at the Snow and Ice Data Centre who monitor Arctic sea ice.
Scientists at the data centre are bracing themselves for the 2005 annual minimum, which is expected to be
reached in mid-September, when another record loss is forecast. A major announcement is scheduled for 20
September. "It looks like we're going to exceed it or be real close one way or the other. It is probably
going to be at least as comparable to September 2002," Dr Serreze said.
"This will be four Septembers in a row that we've seen a downward trend. The feeling is we are reaching a
tipping point or threshold beyond which sea ice will not recover."
The extent of the sea ice in September is the most valuable indicator of its health. This year's record
melt means that more of the long-term ice formed over many winters - so called multi-year ice - has
disappeared than at any time in recorded history.
Sea ice floats on the surface of the Arctic Ocean and its neighbouring seas and normally covers an area of
some 7 million square kilometres (2.4 million square miles) during September - about the size of Australia.
However, in September 2002, this dwindled to about 2 million square miles - 16 per cent below average.
Sea ice data for August closely mirrors that for September and last month's record low - 18.2 per cent
below the monthly average - strongly suggests that this September will see the smallest coverage of
Arctic sea ice ever recorded.
As more and more sea ice is lost during the summer, greater expanses of open ocean are exposed to the sun
which increases the rate at which heat is absorbed in the Arctic region, Dr Serreze said.
Sea ice reflects up to 80 per cent of sunlight hitting it but this "albedo effect" is mostly lost when the
sea is uncovered. "We've exposed all this dark ocean to the sun's heat so that the overall heat content
increases," he explained.
Current computer models suggest that the Arctic will be entirely ice-free during summer by the year 2070
but some scientists now believe that even this dire prediction may be over-optimistic, said Professor
Peter Wadhams, an Arctic ice specialist at Cambridge University.
"When the ice becomes so thin it breaks up mechanically rather than thermodynamically. So these
predictions may well be on the over-optimistic side," he said.
As the sea ice melts, and more of the sun's energy is absorbed by the exposed ocean, a positive feedback is
created leading to the loss of yet more ice, Professor Wadhams said.
"If anything we may be underestimating the dangers. The computer models may not take into account
collaborative positive feedback," he said.
Sea ice keeps a cap on frigid water, keeping it cold and protecting it from heating up. Losing the sea ice
of the Arctic is likely to have major repercussions for the climate, he said. "There could be dramatic
changes to the climate of the northern region due to the creation of a vast expanse of open water where
there was once effectively land," Professor Wadhams said. "You're essentially changing land into ocean and
the creation of a huge area of open ocean where there was once land will have a very big impact on other
climate parameters," he said.
Thursday, September 22, 2005
Hello, Is There Anybody Out There?
With all the worry past and present of this summer's Mother Nature blockbusters, the following article might just be the polar icing on the cake. I don't usually post whole articles, but this deserves full press. Since there has not been much media coverage, I wonder, is anybody listening?