Rising greenhouse gas emissions are making heat waves more severe, but the connection to extreme weather such as droughts and floods is less clear, according to a new report from federal scientists.
Man-made climate change, largely through burning greenhouse gas-emitting fossil fuels that most scientists say warm the planet, did not necessarily explain the 16 extreme weather events for 2013 that the report covered.
“[T]he role of human influences on extreme precipitation events observed in 2013 is decidedly mixed,” said the report, of which three of four editors were National Oceanic and Atmospheric Administration scientists.
The report covered 22 studies spanning 16 extreme weather events last year, including heat waves, droughts and heavy rainfall. Of the five heat waves studied, human activity was found to make them more likely and severe.
But for the droughts, heavy rainfall and storms, “fingerprinting the influence of human activity was more challenging,” NOAA said. That finding hews toward the thinking of many scientists that have been reluctant to point toward climate change causing singular extreme weather events — some have said, though, that climate change may exacerbate certain incidents.
The report does not discount the potential for man-made climate change to affect extreme weather. Part of the problem is a dearth of “observational record” for such events. Instead, the report said a “substantial” man-made contribution “cannot be supported” by the 22 studies it covered.
