Below normal sea surface temperatures and air temperatures are a definitive sign of global warming.
Record-setting weather events — vast floods along the Mississippi River and shockingly destructive tornadoes in the South — have dominated the news in the U.S. for the past several weeks. Up to now, climate scientists have always been careful to say that no particular weather event can be linked directly to climate change. But many climate experts are now pointing linking climate change directly to some of these weather-related disasters.
Kevin Trenberth is head of the Climate Analysis Section at the National Center for Atmospheric Research in Boulder, Colo. funded by the National Science Foundation. In an April interview, Trenberth said he believes that it is “irresponsible not to mention climate change” in the context of extreme weather event – and added that the scientific community is still trying to understand how polluting our atmosphere with billions of tons of greenhouse gases affects tornadic activity.
One of his predecessors at NCAR blamed bad weather during the 1970s on global cooling.