How much does climate change affect extreme weather events, such as the unusually warm temperatures across much of the United States last month or the record-breaking blizzard that struck Denver last week?

A new online report, produced by the University Corporation for Atmospheric Research (UCAR) communications office, summarizes and analyzes cutting-edge research on this topic from leading scientists around the world. The report, “Weather on Steroids,” provides background for reporters, policy makers, and others who need to know how different types of weather events are linked to climate change and the different approaches used by scientists to analyze these links.

“Weather on Steroids” can be found at www2.ucar.edu/atmosnews/attribution. Highlights include:

- An extreme-by-extreme rundown that shows a sliding-scale analysis of different types of weather events and how closely each is related to increased greenhouse gases. Scientists have found strong links between overall climate change and events such as heat waves and intense rainfalls, but the evidence is less clear when it comes to hurricanes and still less for tornadoes.

- An explanation of the different approaches used by leading scientists worldwide when trying to discern possible climate-change connections to weather events such as the deadly 2010 Asian heat wave or last year’s severe Texas drought.  Some researchers, for example, analyze the extent to which a recent extreme event departs from the historical record of weather extremes. Others combine long-term global and local observations with rules of physics that dictate how temperature and water vapor respond to greenhouse gases.

- Contributions from TV weathercasters about the challenges of communicating climate change

- An interview with a prominent reinsurance executive about the business community’s need for accurate climate information.

- A look at where research on this topic is headed. It can take scientists months or even years of intense study to analyze possible links between climate change and an extreme weather event, but they are now developing the tools to make those connections much more quickly through a technique known as event attribution.

- Baseball, steroids, and weather. An animated cartoon illustrates how we can learn about the effects of climate change from a baseball player who has taken steroids.

“Weather on Steroids” details the work by scientists at the U.S. National Center for Atmospheric Research (NCAR), National Oceanic and Atmospheric Administration (NOAA), and Department of Energy; the U.K. Met Office Hadley Centre and University of Oxford; the Postdam Institute for Climate Impact Research in Germany; the University of Cape Town in South Africa, the Intergovernmental Panel on Climate Change; and other key research from around the globe.