Warming caused by human activity was the biggest factor in unusually high temperatures recorded in 2006 in the United States, according to a report by researchers at the National Oceanic and Atmospheric Administration.
The analysis, released Tuesday, is being published in the September issue of Geophysical Research Letters, published by the American Geophysical Union.
Mankind to blame for warming but can slow damage
The report gives a first overview of 3,000 pages of research by the U.N.'s climate panel already published in three installments this year about the science, the likely impacts and the costs of slowing climate change.
The authoritative summary, obtained by Reuters and meant to guide governments in working out how to slow warming, reiterates that humans are to blame for climate change but that clean technologies are available to offset the most harmful emissions.
"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (from human activities) greenhouse gas concentrations," it says.