New analyses find evidence of human-caused climate change in half of the 12 extreme weather and climate events analyzed from 2012

September 5, 2013

Breezy Point, New York, November 14, 2012, in the wake of Hurricane Sandy. U.S. Navy photo by Chief Mass communication Specialist Ryan J. Courtade/Released

The "Explaining Extreme Events of 2012 from a Climate Perspective" report was published today by the Bulletin of the American Meteorological Society. (Full report).

High resolution (Credit: U.S. Navy)

Human influences are having an impact on some extreme weather and climate events, according to the report “Explaining Extreme Events of 2012 from a Climate Perspective” released today by the Bulletin of the American Meteorological Society. Overall, 18 different research teams from around the world contributed to the peer-reviewed report that examined the causes of 12 extreme events that occurred on five continents and in the Arctic during 2012. Scientists from NOAA served as three of the four lead editors on the report.
           
The report shows that the effects of natural weather and climate fluctuations played a key role in the intensity and evolution of the 2012 extreme events. However, in some events, the analyses revealed compelling evidence that human-caused climate change, through the emission of heat-trapping gases, also contributed to the extreme event.

“This report adds to a growing ability of climate science to untangle the complexities of understanding natural and human-induced factors contributing to specific extreme weather and climate events,” said Thomas R. Karl, L.H.D, director of NOAA’s National Climatic Data Center (NCDC). “Nonetheless, determining the causes of extreme events remains challenging.”

In addition to investigating the causes of these extreme events, the multiple analyses of four of the events — the warm temperatures in the United States, the record-low levels of Arctic sea ice, and the heavy rain in both northern Europe and eastern Australia — allowed the scientists to compare and contrast the strengths and weaknesses of their various methods of analysis. Despite their different strategies, there was considerable agreement between the assessments of the same events.

Thomas Peterson, Ph.D., principal scientist at NOAA’s NCDC and one of the lead editors on the report, said, “Scientists around the world assessed a wide variety of potential contributing factors to these major extreme events that, in many cases, had large impacts on society. Understanding the range of influences on extreme events helps us to better understand how and why extremes are changing."

Key findings include:

Location and type of events analyzed in the Paper.

Location and type of events analyzed in the Paper.

High resolution (Credit: NOAA)

Heat Wave and Drought in United States:

Hurricane Sandy Inundation Probability:

Arctic Sea Ice:

Global Rainfall Events:

The report was edited by Peterson, along with Martin P. Hoerling, NOAA’s Earth System Research Laboratory; Peter A. Stott, UK Met Office Hadley Centre and Stephanie C. Herring of NCDC and written by 78 scientists from 11 countries. View the full report online.

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