The United Nation's International Panel on Climate Change released a report on Feb. 2 which stated in no uncertain terms that since the middle of the 20th century, humans have been the main driver of global warming.
The a IPCC report issued in 2001, stated that it was "likely," meaning there was a 66 percent chance, that humans were causing global warming.
Scientists stated in the 2007 IPPC assessment, which was released this month, there is a 90 percent probability that global warming is caused by human activity.
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