With all that's going on in the world, it's easy to miss weather events. So you may not have noticed that U.S. weather patterns the last few months have been quite extreme and worrying.
The graph above shows drought conditions in the U.S. during June 2007 using the "Drought Severity Palmer Index" – the more positive the index (green areas), the wetter the soil, and the more negative the index (red areas), the drier the soil.
As you can see, two large regions of the U.S. – the southeast and the southwest – are experiencing extreme drought. In Georgia and Florida, dry conditions caused failing crops and water shortage alerts. Lake Okeechobee in South Florida, second only to Lake Michigan as the largest fresh water lake in the U.S., and a source of water for millions of people and the Everglades, reached its lowest level ever. Levels were so low that archeological artifacts were revealed on the exposed lake bottom.
The region was also hit with wildfires reported as the most extensive since 1898. In Georgia and Florida alone, more than 1 million acres have burned so far in 2007. At the Florida Climate Summit in Miami last week, I heard Governor Crist report that this year there were wildfires in all but 3 of the more than 90 counties in the state.
In the southwest, California, Nevada, Colorado, and Utah were hit with sweltering heat. Record-breaking or near record-breaking high temperatures were recorded in Reno, Las Vegas, Boise, and Spokane. In Phoenix, Las Vegas, and other cities, temperatures hovered near 110oF or higher.
Meanwhile, the central part of the U.S. – especially Texas, Oklahoma, and Kansas – is awash in water. You might think these folks would appreciate moisture after last year's severe drought with widespread wildfires and crop failures. But not this much moisture. The floods produced by near-record rains have cost lives, destroyed property, and contaminated waters and soils.
Is this extreme weather due to global warming? It's impossible to attribute a specific meteorological episode to a climate trend, but global warming does make extreme weather events more the norm than the exception. And certainly the weather the past few months has been extreme.