Study links climate to human activity

U.S. and British researchers say they have, for the first time, been able to attribute extreme weather events to "human influence on the climate." The National Oceanic and Atmospheric Administration and Britain's National Weather Service, known as the Met Office, said Tuesday researchers were able to conclude that temperatures in Britain last November -- the second-hottest November since record-keeping began in 1659 -- were at least 60 times more likely to have occurred because of climate change than because of natural change in Earth's weather systems, The Guardian reported. Researchers found the 2011 crop-destroying drought and heat wave in Texas was "roughly 20 times more likely" the result of man-made climate change -- warming due to greenhouse gasses -- than of natural climate variation, CBS News reported. Peter Stott, head of Climate Monitoring and Attribution at the Met Office, said the study results indicate "a stronger and stronger picture of human influence on the climate." The researchers cautioned climate change could not be identified as the cause of every extreme weather event, The Guardian reported. But NOAA said the climate change identified in the report issued Tuesday is man-made. CBS News said the researchers evaluated temperature and dryness conditions associated with Texas drought, but nothing in the data for the past 50 years tended to explain the intensity or duration of the 2011 heat wave -- until they accounted for added heat resulting from climate change.