*Scientists confident on human cause of Climate Change

From: Financial Times


CLIMATE CHANGE STUDY POINTS FINGER


Research backs up IPCC assertions

By Fiona Harvey

Scientists have been able to say with virtual certainty for the first
time that the climate change observed over the past four decades is
not the result of natural phenomena but is man made.

The research compounds the conclusion of the biggest scientific report
on global warming to date, the fourth assessment report of the
Intergovernmental Panel on Climate Change (IPCC) last year, which
asserted a strong likelihood that human action was changing the
climate.

The new study raises the likelihood of "unnatural" causes of global
warming to near certainty.

Authors of the study, published today 6 Mbyte PDF in the peer
reviewed journal Nature, examined a greater range of data than any
other study so far. "Changes in natural systems since at least 1970
are occurring in regions of observed temperature increases, and these
temperature increases at continental scales cannot be explained by
natural climate variations alone," they say.

They give warning that man-made climate change is having "a
significant impact on physical and biological systems globally". The
authors of the Nature study, including scientists from the Australia,
China, the US and several other countries, found that more than 90 per
cent of the data sets they examined showed evidence that natural
systems were responding to warming.

Spring is coming earlier, permafrost is melting and coastal erosion is
increasing under the influence of rising sea levels, while animals and
birds are changing their migration and reproductive patterns.

Barry Brook, director of climate change research at the University of
Adelaide, said: "[We should] consider that there has been only 0.75ºC
of temperature change so far, yet the expectation for this century is
four to nine times that amount.

"So these changes are only a minor portent of what is likely to come,
especially if we continue on our carbon-profligate pathway."

Climate scientists know they may be facing difficult times ahead in
persuading the public and politicians of the urgency of global
warming, as research published recently in Nature suggested that
global temperatures were not likely to increase in the next decade,
and could even decline.

Scientists from Germany's Leibniz Institute of Marine Sciences and the
UK Met Office's Hadley Centre say natural variations in the climate
linked to the Pacific cooling system known as La Nina, and a cooling
phase of a system of Atlantic currents called the meridional
overturning circulation, may push down temperatures despite the
effects of greenhouse gases.

After those effects wear off, within about a decade, temperatures are
likely to rise much more strongly as the warming effect of carbon
emissions regains the upper hand in altering the climate.

Scientists fear that the expected lull in temperature rises might
dispel any sense of urgency in tackling global warming and provide
ammunition for climate change sceptics.