- Global warming is made worse by man-made
pollution and the scale of the problem is unprecedented in at least
20,000 years, according to a draft report by the world's leading
climate scientists.
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- The leaked assessment by the group of
international experts says there is now overwhelming evidence to
show that the Earth's climate is undergoing dramatic transformation
because of human activity.
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- A draft copy of the report by a working
group of the Intergovernmental Panel on Climate Change (IPCC) states
that concentrations of carbon dioxide, methane and other greenhouse
gases are at the highest for at least 650,000 years.
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- It predicts that global average temperatures
this century will rise by between 2C and 4.5C as a result of the
doubling of carbon dioxide levels caused by man-made emissions.
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- These temperatures could increase by
a further 1.5C as a result of "positive feedbacks" in the
climate resulting from the melting of sea ice, thawing permafrost
and the acidification of the oceans.
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- The draft report will become the fourth
assessment by the IPCC since it was established in 1988 and was meant
to be confidential until the final version is ready for publication
next year.
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- However, a copy of the report has been
made available by a US government committee and can be found on the
internet by anyone who makes an e-mail request for a password to
access the area on its website.
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- The US Climate Change Science Programme,
which yesterday released its own report saying climate change was
being affected by man-made pollution, said it wanted as many experts
and stakeholders as possible to comment on the draft IPCC report.
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- The IPCC's chairman, Rajendra Pachauri,
however, did not learn of the decision to, in effect, publish the
report until it was posted online, according to the journal Nature.
The IPCC assessment is written by scores of scientists - who can
draw on the expertise of hundreds more researchers - to produce the
most definitive and authoritative assessment of climate change and
its impacts.
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- Global warming sceptics will get little
comfort from the confident language in the draft report, which dismisses
suggestions that climate change is an entirely natural rather than
man-made phenomenon.
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- "There is widespread evidence of
anthropogenic warming of the climate system in temperature observations
taken at the surface, in the free atmosphere and in the oceans,"
it says.
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- "It is very likely that greenhouse
gas forcing has been the dominant cause of the observed global warming
over the past 50 years.
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- "And it is likely that greenhouse
gases alone would have caused more warming than has been observed
during this period, with some warming offset by cooling from natural
and other anthropogenic factors." Since its last report in 2001,
the IPCC's working group says it has amassed convincing evidence
showing that climate change is already happening.
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- It also finds that climate change is
set to continue for decades and perhaps centuries to come even if
man-made emissions can be curbed.
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- "2005 and 1998 were the warmest
two years on record. Five of the six warmest years have occurred
in the past five years (2001-2005)," the report says.
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- Satellite data since 1978 shows that
the Arctic sea ice has shrunk by about 2.7 per cent each decade,
with even larger losses of about 7.4 per cent during the warmer summer
months.
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- "The smallest extent of summer sea
ice was observed in 2005. Average Arctic temperatures have been rising
since the 1960s and 2005 was the warmest Arctic year," the draft
IPCC report says.
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- "An increasing body of evidence
suggests a discernible human influence on other aspects of climate,
including sea ice, heat waves and other extremes, circulation, storm
tracks and precipitation," it says.
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- Melting glaciers and polar ice sheets
could cause sea levels to rise by up to 43cm by 2100, and the rise
for the next two centuries is predicted to be nearly double that
figure.
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- Man-made emissions of greenhouse gases
have probably already caused the increase in sea levels observed
over the past century, says the report.
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- "Anthropogenic forcing, resulting
from thermal expansion from ocean warming and glacier and ice sheet
melt, is likely the largest contributor to sea level rise during
the latter half of the 20th century," the report says.
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- "Anthropogenic forcing has likely
contributed to recent decreases in Arctic sea ice extent. There is
evidence of a decreasing trend in global snow cover and widespread
retreat of glaciers consistent with warming and evidence that this
melting has also contributed to sea-level rise," it adds.
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- Evidence of climate change
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- * Arctic sea ice has shrunk by 2.7 per
cent per decade since 1978 and by 7.4 per cent each decade during
the summer months.
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- * Five of the six warmest years have
occurred in the past five years, with 2005 and 1998 being the two
warmest years on record.
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- * Global average sea levels rose at a
rate of about 2mm a year between 1961-2003, and by an average of
more than 3mm a year between 1993-2003.
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- * Mountain glaciers and polar land ice
have in general melted faster than they have formed over the past
40 years.
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- * Permafrost temperatures have increased
on average and the area covered by seasonally frozen ground has decreased
by about 7 per cent over the past 50 years.
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- © 2006 Independent News and Media
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