Download Glacier Melt Could Signal Faster Rise in Ocean Levels

3 Articles on Global Warming– COUNT AS 1 RDG FOR RDP’s
#1
Glacier Melt Could Signal Faster Rise in Ocean Levels
By Shankar Vedantam
Washington Post Staff Writer
Friday, February 17, 2006; A01
Greenland's glaciers are melting into
the sea twice as fast as previously
believed, the result of a warming trend
that renders obsolete predictions of how
quickly Earth's oceans will rise over the
next century, scientists said yesterday.
The new data come from satellite
imagery and give fresh urgency to
worries about the role of human activity
in global warming. The Greenland data
are mirrored by findings from Bolivia to
the Himalayas, scientists said, noting
that rising sea levels threaten
widespread flooding and severe storm
damage in low-lying areas worldwide.
Seasonal surface melt extent on the Greenland Ice Sheet has been observed
by satellite since 1979 and shows an increasing trend. The melt zone, where
summer warmth turns snow and ice around the edges of the ice sheet into
slush and ponds of meltwater, has been expanding inland and to record high
elevations in recent years (source: Arctic Impacts of Arctic Warming,
Cambridge Press, 2004).
The scientists said they do not yet
understand the precise mechanism causing glaciers to flow and melt more rapidly, but they said
the changes in Greenland were unambiguous -- and accelerating: In 1996, the amount of water
produced by melting ice in Greenland was about 90 times the amount consumed by Los
Angeles in a year. Last year, the melted ice amounted to 225 times the volume of water that
city uses annually.
"We are witnessing enormous changes, and it will take some time before we understand how it
happened, although it is clearly a result of warming around the glaciers," said Eric Rignot, a
scientist at the California Institute of Technology's Jet Propulsion Laboratory.
The Greenland study is the latest of several in recent months that have found evidence that
rising temperatures are affecting not only Earth's ice sheets but also such things as plant
and animal habitats, coral reefs' health, hurricane severity, droughts, and globe-girdling
currents that drive regional climates.
The ice sheets in Greenland and Antarctica are among the largest reservoirs of fresh water on
Earth, and their fate is expected to be a major factor in determining how much the oceans will
rise. Rignot and University of Kansas scientist Pannir Kanagaratnam, who published their
findings yesterday in the journal Science, declined to guess how much the faster melting would
raise sea levels but said current estimates of around 20 inches over the next century are probably
too low.
While sea-level increases of a few feet may not sound like very much, they could have profound
consequences on flood-prone countries such as Bangladesh and trigger severe weather around
the world.
"The implications are global," said Julian Dowdeswell, a glacier expert at the University of
Cambridge in England who reviewed the new paper for Science. "We are not talking about
walking along the sea front on a nice summer day, we are talking of the worst storm settings,
the biggest storm surges . . . you are upping the probability major storms will take place."
The study also highlights how seemingly small changes in temperature can have extensive
effects. Where glaciers in Greenland were once traveling around four miles per year, they
are now moving twice as fast. While it is possible that increased precipitation in northern
Greenland is somehow compensating for the melting in the south, the scientists said that is
unlikely.
There are multiple ways warming might be causing glaciers to accelerate. The scientists said
increased temperatures may loosen the grip that glaciers have on underlying bedrock, or melt
away floating shelves along the shore that can hold ice in place.
Whatever the mechanism, the phenomenon seems widespread. At a news conference organized
by the American Association for the Advancement of Science at its annual meeting in St. Louis,
glacier scientists Vladimir Aizen from the University of Idaho and Gino Casassa of Chile's
Centro de Estudios Cientificos said they were seeing the same thing happen to glaciers in the
Himalayas and South America.
"Glaciers have retreated systematically and in an accelerated fashion in the last few decades,"
Casassa said. One glacier that provided Bolivia with its only ski slope five years ago has
splintered into three and cannot be used for skiing, the scientist added.
Rapid melting of Himalayan glaciers also raises concerns for the large portion of humankind that
gets its fresh water from glacier-fed rivers in South Asia, Aizen noted.
Most climate scientists believe a major cause for Earth's warming climate is increased emissions
of greenhouse gases as a result of burning fossil fuels, largely in the United States and other
wealthy, industrialized nations such as those of western Europe but increasingly in rapidly
developing nations such as China and India as well. Carbon dioxide and several other gases trap
the sun's heat and raise atmospheric temperature.
"This study underscores the need to take swift, meaningful actions at home and abroad to address
climate change," said Vicki Arroyo, director of policy analysis at the Pew Center on Global
Climate Change.
The data highlight the lack of meaningful U.S. policy, she added: “This is the kind of study that
should make people stay awake.”
#2
Warming Hits 'Tipping Point'
Siberia feels the heat It's a frozen peat bog the size of France and Germany
combined, contains billions of tonnes of greenhouse gas and, for the first time
since the ice age, it is melting
By Ian Sample August 11, 2005 by the Guardian/UK
A vast expanse of western Siberia is undergoing an unprecedented thaw that could dramatically increase
the rate of global warming, climate scientists warn today.
Researchers who have recently returned from the region found that an area of permafrost spanning a
million square kilometers - the size of France and Germany combined - has started to melt for the first
time since it formed 11,000 years ago at the end of the last ice age.
The area, which covers the entire sub-Arctic region of western Siberia, is the world's largest
frozen peat bog and scientists fear that as it thaws, it will release billions of tonnes of methane, a
greenhouse gas 20 times more potent than carbon dioxide, into the atmosphere.
It is a scenario climate scientists have feared since first identifying "tipping points" - delicate
thresholds where a slight rise in the Earth's temperature can cause a dramatic change in the
environment that itself triggers a far greater increase in global temperatures.
The discovery was made by Sergei Kirpotin at Tomsk State University in western Siberia and Judith
Marquand at Oxford University and is reported in New Scientist today.
The researchers found that what was until recently a barren expanse of frozen peat is turning into a
broken landscape of mud and lakes, some more than a kilometer across.
Dr Kirpotin told the magazine the situation was an "ecological landslide that is probably irreversible and is
undoubtedly connected to climatic warming". He added that the thaw had probably begun in the past
three or four years.
Climate scientists yesterday reacted with alarm to the finding, and warned that predictions of
future global temperatures would have to be revised upwards.
"When you start messing around with these natural systems, you can end up in situations where
it's unstoppable. There are no brakes you can apply," said David Viner, a senior scientist at the
Climatic Research Unit at the University of East Anglia.
"This is a big deal because you can't put the permafrost back once it's gone. The causal effect is
human activity and it will ramp up temperatures even more than our emissions are doing."
In its last major report in 2001, the intergovernmental panel on climate change predicted a rise in global
temperatures of 1.4C-5.8C between 1990 and 2100, but the estimate only takes account of global
warming driven by known greenhouse gas emissions.
"These positive feedbacks with landmasses weren't known about then. They had no idea how
much they would add to global warming," said Dr Viner.
Western Siberia is heating up faster than anywhere else in the world, having experienced a rise of some
3C in the past 40 years. Scientists are particularly concerned about the permafrost, because as it thaws,
it reveals bare ground which warms up more quickly than ice and snow, and so accelerates the rate at
which the permafrost thaws.
Siberia's peat bogs have been producing methane since they formed at the end of the last ice age, but
most of the gas had been trapped in the permafrost. According to Larry Smith, a hydrologist at the
University of California, Los Angeles, the west Siberian peat bog could hold some 70bn tons of methane,
a quarter of all of the methane stored in the ground around the world.
The permafrost is likely to take many decades at least to thaw, so the methane locked within it will not be
released into the atmosphere in one burst, said Stephen Sitch, a climate scientist at the Met Office's
Hadley Center in Exeter.
But calculations by Dr Sitch and his colleagues show that even if methane seeped from the permafrost
over the next 100 years, it would add around 700m tons of carbon into the atmosphere each year, roughly
the same amount that is released annually from the world's wetlands and agriculture.
It would effectively double atmospheric levels of the gas, leading to a 10% to 25% increase in global
warming, he said.
Tony Juniper, director of Friends of the Earth, said the finding was a stark message to politicians to take
concerted action on climate change. "We knew at some point we'd get these feedbacks happening that
exacerbate global warming, but this could lead to a massive injection of greenhouse gases.
"If we don't take action very soon, we could unleash runaway global warming that will be beyond our
control and it will lead to social, economic and environmental devastation worldwide," he said. "There's
still time to take action, but not much.
"The assumption has been that we wouldn't see these kinds of changes until the world is a little warmer,
but this suggests we're running out of time."
In May this year, another group of researchers reported signs that global warming was damaging the
permafrost. Katey Walter of the University of Alaska, Fairbanks, told a meeting of the Arctic Research
Consortium of the US that her team had found methane hotspots in eastern Siberia. At the hotspots,
methane was bubbling to the surface of the permafrost so quickly that it was preventing the surface from
freezing over.
#3
Dramatic Change in West Antarctic Ice Could Produce
16ft Rise in Sea Levels
by Michael McCarthy
February 2, 2005, the Independent/UK
British scientists have discovered a new threat to the world which may be a result of global warming.
Researchers from the Cambridge-based British Antarctic Survey (BAS) have discovered that a massive
Antarctic ice sheet previously assumed to be stable may be starting to disintegrate, a conference
on climate change heard yesterday. Its collapse would raise sea levels around the earth by more
than 16 feet.
BAS staff are carrying out urgent measurements of the remote points in the West Antarctic Ice Sheet
(WAIS) where they have found ice to be flowing into the sea at the enormous rate of 250 cubic
kilometers a year, a discharge alone that is raising global sea levels by a fifth of a millimeter a
year.
Professor Chris Rapley, the BAS director, told the conference at the UK Meteorological Office in Exeter,
which was attended by scientists from all over the world, that their discovery had reactivated worries
about the ice sheet's collapse.
Only four years ago, in the last report of the UN's Intergovernmental Panel on Climate Change (IPCC),
worries that the ice sheet was disintegrating were firmly dismissed.
Professor Rapley said: "The last IPCC report characterized Antarctica as a slumbering giant in terms of
climate change. I would say it is now an awakened giant. There is real concern."
He added: "The previous view was that WAIS would not collapse before the year 2100. We now
have to revise that judgment. We cannot be so sanguine." Collapse of the WAIS would be a disaster,
putting enormous chunks of low-lying, desperately poor countries such as Bangladesh under water - not
to mention much of southern England.
The conference has been called by Tony Blair as part of Britain's efforts to increase the pace of
international action on climate change, in a year when the UK is heading the G8 group of industrialized
nations and the European Union.
Mr Blair has asked it to explore the question of how much climate change the world can take before the
consequences are catastrophic for human society and ecosystems.
Yesterday, it heard several alarming new warnings of possible climate-related catastrophic events,
including the failure of the Gulf Stream, which keeps the British Isles warm, and the melting of the ice
sheet covering Greenland.
But it was the revelations of Professor Rapley, head of one of the world's most respected scientific
bodies, which were the most dramatic, as they reopened a concern many scientists assumed had been
laid to rest.
Antarctica as a whole is a land covered by very thick ice, but the ice sheet covering the eastern half of the
continent is very stable as it sits on rocks that are well above sea level.
Worries about the ice covering the western half first surfaced more than 25 years ago when it was
realized that the base rocks are actually well below the level of the sea.
In some circumstances, it was feared, such as a melting of the edge of the ice sheet from rising
temperatures, sea water could get under it and eventually lead to its collapse.
Yet the 2001 IPCC report, the principal consensus view of the international community of climate
scientists, thought that very unlikely, and said such a collapse was improbable before the end of
the current century, or even for 1,000 years.
What puts a very big question mark over this, Professor Rapley said, was the recent discovery of
the extremely rapid discharge of ice into the Amundsen sea from the WAIS at three remote ice
streams, Pine Island, Thwaites, and another unnamed site.
"There is a very dramatic discharge from this region which, five years ago when the IPCC report
was written, we just didn't know about," he said. "What we have found completely opens up the
whole debate." It had only been recently discovered, he said, because the area was so remote. But BAS
scientists, with US help, had established a base in the area to investigate. Professor Rapley said there
was some evidence that the discharge was a relatively recent phenomenon and it might be caused by
rising ocean temperatures.
Margaret Beckett, the Environment Secretary, who opened the conference, added another
ominous prediction when she said that major global warming impacts on the world in the next 20
to 30 years could not be avoided. Whatever we do, potentially disastrous world temperature rises
will take place because they are already "built into the system," she said.
Her forecast that we are powerless to prevent major damage from climate change is accepted by
scientists but it is rare for such a frank admission from a politician. It reflects the concern at a high
level.
It was amplified by senior climate researchers, who said the amount of future warming to which the world
is firmly committed, because of greenhouse gases that have already been put into the atmosphere, will
be enough to threaten the survival of many ecosystems and wildlife species such as polar bears and
penguins.
"I believe that most of the warming we are expecting over the next few decades is now virtually inevitable,
and even in this time frame we may expect a significant impact," Mrs Beckett said.
© 2005 Independent News & Media (UK) Ltd.