On June 19, the US Climate Change Science Program (CCSP) released Synthesis and Assessment Product 3.3 entitled “Weather and Climate Extremes in a Changing Climate. Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands,” highlighting the likely changes in extreme weather and climate conditions under ongoing climate change. The study provides the most comprehensive assessment yet of how global warming has helped to transform the climate of the United States and Canada over the past 50 years—and how it may do so in the future. It warned that extreme weather events “are among the most serious challenges to society in coping with a changing climate.” Thomas R. Karl, director of the National Climatic Data Center, said, “This report addresses one of the most frequently asked questions about global warming: What will happen to weather and climate extremes?” He added that the report, which synthesizes the findings of more than 100 academic papers, “concludes that we are now witnessing and will increasingly experience more extreme weather and climate events.”

The study says as greenhouse gas (GHG) emissions rise, North America is likely to experience more droughts and excessive heat in some regions even as intense downpours and hurricanes strike others more often. The scientists reported that the last decade has seen fewer cold snaps than any other 10-year period in the historical record dating back to 1895. The study says under a middle-range scenario of future GHG emissions, climate models indicate that by mid-century extremely hot days that now occur only once every 20 years will occur every three years. By the end of the century, models predict that intense bouts of precipitation that might have occurred once every 20 years will take place every five years.

For more information see:

Weather and Climate Extremes in a Changing Climate

Washington Post: Report on Climate Predicts Extremes