Scientists' confidence increases in man's influence on climate change

  • July was the sixth-warmest on record, according to the National Climatic Data Center.
July was the sixth-warmest on record, according to the National… (NCDC )
August 21, 2013|By Scott Dance, The Baltimore Sun

Scientists are increasingly confident that human activity is influencing changes in climate across the globe, according to leaked copies of a United Nations report detailed by several news outlets.

The U.N.'s Intergovernmental Panel on Climate Change is expected to report next month that it is at least 95 percent likely that humans have contributed to increased global temperatures, largely through burning of fossil fuels, according to Reuters, the New York Times and now the Washington Post.

While the level of confidence is increased from past years' reports, there is less certainty in what the impacts will be in specific communities, Reuters reported Friday:

That is up from at least 90 percent in the last report in 2007, 66 percent in 2001, and just over 50 in 1995, steadily squeezing out the arguments by a small minority of scientists that natural variations in the climate might be to blame.

That shifts the debate onto the extent of temperature rises and the likely impacts, from manageable to catastrophic. Governments have agreed to work out an international deal by the end of 2015 to rein in rising emissions.

"We have got quite a bit more certain that climate change ... is largely manmade," said Reto Knutti, a professor at the Swiss Federal Institute of Technology in Zurich. "We're less certain than many would hope about the local impacts."

A monthly report by the National Climatic Data Center released Tuesday found July's temperatures worldwide were the sixth-highest recorded since record-keeping began in 1980. It was a 341st consecutive month with global temperatures above the 20th century average.

Read the report here.

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