Climate change: scientists warn it's too late to save the ice caps
Pastor Dale Morgan
Climate change: scientists warn it's too late to save the ice caps*
David Adam, environment correspondent
Monday February 19, 2007
The Guardian
A critical meltdown of ice sheets and severe sea level rise could be
inevitable because of global warming, the world's scientists are
preparing to warn their governments. New studies of Greenland and
Antarctica have forced a UN expert panel to conclude there is a 50%
chance that widespread ice sheet loss "may no longer be avoided" because
of greenhouse gases in the atmosphere.
Such melting would raise sea levels by four to six metres, the
scientists say. It would cause "major changes in coastline and
inundation of low-lying areas" and require "costly and challenging"
efforts to move millions of people and infrastructure from vulnerable
areas. The previous official line, issued in 2001, was that the chance
of such an event was "not well known, but probably very low".
The melting process could take centuries, but increased warming caused
by a failure to cut emissions would accelerate the ice sheets' demise,
and give nations less time to adapt to the consequences. Areas such as
the Maldives would be swamped and low-lying countries such as the
Netherlands and Bangladesh, as well as coastal cities including London,
New York and Tokyo, would face critical flooding.
The warning appears in a report from the Intergovernmental Panel on
Climate Change, which assesses the likely impacts of global warming and
will be published in April. A final draft of the report's
summary-for-policymakers chapter, obtained by the Guardian, says: "Very
large sea level rises that would result from widespread deglaciation of
Greenland and West Antarctic ice sheets imply major changes in
coastlines and inundation of low-lying areas, with greatest effects in
river deltas.
"Relocating populations, economic activity and infrastructure would be
costly and challenging. There is medium confidence that both ice sheets
would be committed to partial deglaciation for a global average
temperature increase greater than 1-2C, causing sea level rise of 4-6m
over centuries to millennia." Medium confidence means about a five in 10
chance.
The revelation comes as a new report points out that greenhouse gas
emissions running into hundreds of millions of tonnes have not been
disclosed by Britain's biggest businesses, masking the full extent of
the UK's contribution to global warming. According to a report by
Christian Aid, only 16 of Britain's top 100 listed companies are meeting
the government's most elementary reporting guidelines on greenhouse gas
emissions. As a result, almost 200m tonnes of damaging CO2 is estimated
to be missing from the annual reports of FTSE 100 companies. The figure
is more than the annual reported emissions of Pakistan and Greece combined.
This month the IPCC published a separate study on the science of climate
change, which concluded that humans are "very likely" to be responsible
for most of the recent warming, and that average temperatures would
probably increase by 4C this century if emissions continue to rise. Even
under its most optimistic scenario, based on a declining world
population and a rapid switch to clean technology, temperatures are
still likely to rise by 1.8C.
The new report is expected to say this means there is "a significant
probability that some large-scale events (eg deglaciation of major ice
sheets) may no longer be avoided due to historical greenhouse gas
emissions and the inertia of the climate system". Scientists involved
with the IPCC process cannot talk publicly about its contents before
publication. But a senior author on the report said: "It's not rocket
science to realise that with the numbers coming out from the IPCC
[science report], the warming by the end of the century is enough to do
that." The report's conclusion poses a conundrum for governments of how
to address a problem that is inevitable but may not occur for hundreds
or thousands of years. "That's for the policy makers to decide but it
really is a very difficult question," the source said. "Those are moral
questions and the answer you give will depend very much on which part of
the world you live in."
Jonathan Overpeck, a climate scientist at the University of Arizona,
said the key question was not whether the ice sheets would break up, but
how quickly. Some models suggest rapid melting that would bring sea
level rises of more than a metre per century. "That would be much harder
for us to cope with," he says.
The IPCC science report predicted sea level rises of up to 0.59m by the
end of the century. But that does not include the possible contribution
from ice sheets, because the experts judged it too unpredictable to
forecast over short timescales.