There have always been extreme weather events, so why are scientists talking so much about extreme events now?

Recent climate research synthesized in the 2007 and 2014 Intergovernmental Panel on Climate Change Assessment Reports documents that there have been observable changes in extreme weather events over the past fifty years that are consistent with the expected impacts in a warming climate. The report shows that there has been a significant shift towards fewer cold and more heat extremes across many parts of the globe over the past fifty years. The 2014 National Climate Assessment reaffirms that U.S. average