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["Keaney Michael" <Michael.Keaney@xxxxxx>]

Climate of change is here for good
By Steve Connor, Science Editor
The Independent, 20 March 2002

Glaciologists from the British Antarctic Survey in Cambridge said
yesterday that the 500-billion-ton Larsen B ice shelf is no more.
Another team of Antarctic scientists in America said that they had
spotted a huge iceberg half the size of Cyprus floating majestically
away from the frozen continent.

Meanwhile, closer to home, climate researchers from East Anglia
University have found that the British growing season - as defined by
the period between two cold snaps lasting five consecutive days - is now
longer than ever.

"If the trend continues, it is possible that we will have a year-round
growing season within a generation," predicted Tim Mitchell of East
Anglia's Tyndall Centre for Climate Change Research.

At the same time, their colleagues at University College London have
calculated that we are heading for a balmy spring. They forecast that
temperatures will be as much as 1.3C warmer than the 30-year seasonal
norm.

Who, other than President Bush, would dare to dispute the reality of
global warming? With such hard evidence visible to all, it seems
patently obvious that man-made greenhouse gases are causing a
catastrophic change to the world's climate.

In truth, many of the scientists behind these latest observations would
be the first to question the assumption that greenhouse gases are
responsible for what they are seeing. Melting ice, milder winters and
warmer springs, they would argue, may fit in with global warming, but
they do not amount to indisputable proof.

"The fact that spring is going to be warmer is consistent with global
warming but no more. Global warming is the obvious explanation, and I
don't think there a better one, but we can't say more than that," said
Mark Saunders, from UCL's Benfield Greig Hazard Research Centre.

But what about that giant iceberg, called B-22, which the US National
Ice Centre in Washington said on Monday had broken away from an ice
tongue in the Amundsen Sea, an area of Antarctica south of the Pacific
Ocean? Measuring 40 miles wide and 53 miles long, B-22 could accommodate
nine city states the size of Singapore - and still have room for a golf
course.

Big icebergs "calving" from the Antarctic mainland are unusual but by no
means unprecedented. According to David Vaughan, a glaciologist from the
British Antarctic Survey in Cambridge, it would be unusual if we did not
see them floating away.

"We expect big icebergs to fall off the Antarctic ice sheet now and
again. It's normal because the ice that is lost is constantly being
replaced by snowfall," Dr Vaughan said.

So the calving of B-22 has little or nothing to do with the global
warming debate. "It's a red, or rather white herring," explained Dr
Vaughan.

A far more important observation is that the Larsen B ice shelf in the
Antarctic peninsula, which juts out towards the tip of South America,
has over the past month collapsed and disintegrated into thousands of
small icebergs.

According to Dr Vaughan this is only the second time that he or any of
his colleagues have witnessed the disintegration of such a large chunk
of floating ice - this one being 670 feet thick and covering an area of
1,255 square miles.

"Glaciologists have only seen this kind of event once before and that
was in 1995 when the nearby Larsen ice shelf A collapsed," Dr Vaughan
said.

Although the Larsen B ice shelf's disappearance has been well
documented, the speed of its final demise has astonished scientists.

"It's been retreating for 10 or 15 years and this slow retreat, which is
driven by regional climate change, developed into a total collapse, like
a bridge that had one too many bricks taken out of it," Dr Vaughan said.

The Larsen ice shelves have been stable for centuries and there is no
obvious reason why they should be melting now, apart from the fact that
the regional climate of this part of Antarctica is warming at five times
the rate of the rest of the world. No one knows exactly why this is
happening. It could be a change in the local wind patterns, or ocean
circulation, or some little-understood "feedback" mechanism causing more
and more heat to be pumped into the peninsula.

But whatever the reason, for it not to be connected in some way to the
global warming would be remarkable. "If the two things were coincidental
then it would be extremely surprising. One of the best candidates
available to explain why this regional climate change has happened is
that it has been kicked off by a global climate change," Dr Vaughan
said.

"We're fairly confident that the present ice shelves have probably been
there for about 1,800 years so. Before then many of these ice shelves
were absent, probably because the climate on the continent was as warm
or warmer than it is now," Dr Vaughan said.

"We can see this warming in the Antarctic peninsula, we know that it is
geographically unusual and unusual in the timescale of 1,800 years, what
we can't say is what has caused it," he said.

"I can't with my hand on my heart link it to global warming, or link it
to enhanced greenhouse gas warming with absolute surety."

Ice shelves float on the sea, but they are attached to the Antarctic
mainland. When they melt they do not affect sea levels - on the same
principle that a melting ice cube in a gin and tonic does not increase
the level of the drink in the glass.

But if ice shelves do not affect sea levels directly, they are thought
to be critical when it comes to preventing the mainland ice sheets -
where much of the planet's water has been locked away for thousands of
years - from slipping into the sea.

One of the greatest fears is that as ice shelves collapse, the ice
sheets on the mainland will become more unstable, leading to mass
melting into the surrounding oceans and a catastrophic rise in sea
levels.

So far, there is little evidence that other ice shelves are going the
way of Larsen, but for how long this will remain the case is any one's
guess.

"We expect more ice shelves further south to eventually be attacked in
the same way, but it's unlikely that the really big ice shelves - like
Ross and Ronne -- will be attacked in the near future, meaning the next
few decades. They appear to be stable at the moment," Dr Vaughan said.

The real problem for scientists is marrying up the overall changes to
global temperatures with the actual observations from different regions
of the world. The UN's Intergovernmental Panel on Climate Change says
that all the evidence suggests a link with man-made emissions, but
trying to prove a sequence of cause and effect with one particular
phenomenon is proving hard to do.

All that the IPCC scientists can say is that the global warming seen
over the past 50 years can now be attributable to human activities and
that "an increasing body of observations gives a collective picture of a
warming world and other changes in the climate system".

We still have some way to go before science can categorically say that a
melting ice shelf on the other side of the world is caused by the same
phenomenon resulting in a longer growing season in Britain.

Natural or man made?

Ocean currents changing direction: One of the biggest fears of global
warming is that the ocean circulation could slow down or flip into
reverse. Scientists have found that a crucial part of the North Atlantic
"conveyor belt" is slowing down but cannot as yet attribute it directly
to a warmer world.

Tropical diseases in Britain: A warmer world and milder winters could
lead to an explosion of insects and other pests that normally live
farther south. One global warming nightmare is the possible return of
malaria to the UK - but malaria did not need warmer weather when it was
eradicated less than 100 years ago.

Warmer summers, wetter winters: The 1990s were the warmest years on
record and winters have been noticeably wetter and warmer. However,
although this is unusual, some climatologists say that it could still be
within the natural variation of the British weather - a notoriously
fickle phenomenon.

The North Pole is melting:

Anecdotal reports of tourists cruising on ocean liners suggested that
the North Pole melted last summer. Scientists later pointed out that
seasonal melting was a natural phenomenon, although the Arctic ice is
known to be considerably thinner now compared with 50 years ago.

Full article at:
http://news.independent.co.uk/world/environment/story.jsp?story=276363

Michael Keaney
Mercuria Business School
Martinlaaksontie 36
01620 Vantaa
Finland

michael.keaney@xxxxxx