http://www.nzherald.co.nz/science/news/article.cfm?c_id=82&objectid=10630087Humans to blame for climate change - scientistsBy Steve Connor
12:45 PM Friday Mar 5, 2010
Man-made emissions are largely to blame for climate change, according to new research. File photo / Alan Gibson
Climate scientists have delivered a powerful riposte to their sceptical critics with a study that strengthens the case for saying global warming is largely the result of man-made emissions of greenhouse gases.
The researchers found that no other possible natural phenomenon, such as volcanic eruptions or variations in the activity of the sun, could explain the significant warming of the planet over the past half century as recorded on every continent including Antarctica.
It is only when the warming effect of emitting millions of tonnes of carbon dioxide into the atmosphere from human activity is considered that it is possible to explain why global average temperatures have risen so significantly since the middle of the 20th century.
The study updates a 2007 report by the Intergovernmental Panel on Climate Change and has discovered several new elements of the global climate which have been influenced by humans, such as an increasing amount of water vapour evaporating from the warmer oceans into the atmosphere and a corresponding increase in the saltiness of the sea.
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The review, led by Peter Stott of the Met Office Hadley Centre in Exeter, found the "fingerprints" of human activity on many different aspects of climate change, including the overall warming of the Antarctic recently documented for the first time by other researchers.
"The observations cannot be explained by natural factors," Dr Stott said. Since 1980, the Earth has warmed by about 0.5C and is now warming at a rate of about 0.16C per decade, with even higher rates at higher latitudes such as in the Arctic.
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