The work, by an international team, is published in Nature Geoscience
journal.
In 2007, the UN's climate change body presented strong scientific evidence
the rise in average global temperature is mostly due to human activities.
This contradicted ideas that it was not a result of natural processes such as
an increase in the Sun's intensity.
Now that gap in research has been plugged, according to scientists
who carried out a detailed analysis of temperature variations at both poles.
Their study indicates that humans have indeed contributed to warming in both
regions.
Researchers expected this result for the Arctic - because of the recent sharp
increase in the melting of sea ice in the summer in the region - but temperature
variations in the Antarctic have until now been harder to interpret.
Today's study, according to the researchers, suggests for the first time that
there's a discernable human influence on both the Arctic and Antarctica.
Best fit
The research team took the temperature changes over the polar regions of the
Earth and compared them with two sets of climate models.
One set assumed that there had been no human influence the other set assumed
there had.
The best fit was with models that assumed that human activities including the
burning of fossil fuels and depletion of ozone had played a part.
According to one of the researchers involved with the study, Peter Stott,
head of climate monitoring and attribution at the Met Office, formally showing
that the Antarctic was being influenced by human activities was the key
development
"In the recent IPCC (Intergovernmental Panel on Climate Change) report for
example," he said, "it wasn't possible to make a statement about the Antarctic
because such a study had not been done at that point.
"But nevertheless when you do that you see a clear human fingerprint in the
observed data. We really can't claim anymore that it's natural variations that
are driving these very large changes that we are seeing in our in the climate
system."
Professor Phil Jones, director of the Climate Research Unit at the University
of East Anglia, said: "Our study is certainly closing a couple of gaps in the
last IPCC report.
"But I still think that a number of people, including some politicians, are
reluctant to accept the evidence or to do anything about it until we
specifically come down to saying that one particular event was caused by humans
like a serious flood somewhere or even a heatwave.
"Until we get down to smaller scale events in both time and space I still
think there will be people doubting the evidence."
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