2012 another record-setter, fits climate forecasts

In 2011, the United States set a record with 14 billion-dollar weather disasters. The National Oceanic and Atmospheric Administration has a preliminary count of 11 such disasters this year. And NOAA's official climate extreme index, which tallies disasters and rare events like super-hot days, is on pace to set its own record.

Arndt points to the geographic heart of America, the Mississippi River, as emblematic.

On May 6, 2011, the Mississippi River at New Madrid, Mo., crested at its highest point on record. Less than 16 months later on Aug. 30, 2012, the same spot on the river was more than 53 feet lower, hitting an all-time low water mark.

The U.S. went through the same lurching extremes on tornadoes. Those storms killed 553 people last year, Furgione said. This year began with many tornadoes, then in April they just stopped. April to November, normal tornado season, saw the fewest F1 or stronger tornadoes in the U.S. ever.

"Every year is bringing different types of extreme weather and climate events," NOAA chief Jane Lubchenco said. "All storms today are happening in a climate-altered world."

Not everything is connected to man-made global warming, climate scientists say. Some, like tornadoes, have no scientifically discernible connection. Others, like the East Coast superstorm, will be studied to see if climate change is a cause, although scientists say rising sea levels clearly worsened flooding. They are more convinced that the heat waves of last summer are connected to global warming.

These are "clearly not freak events," but "systemic changes," said climate scientist Stefan Rahmstorf of the Potsdam Institute in Germany. "With all the extremes that, really, every year in the last 10 years have struck different parts of the globe, more and more people absolutely realize that climate change is here and already hitting us."

In 1988, NASA scientist James Hansen, sometimes called the godfather of global warming science, ran computer models that predicted the decade of the 2010s would see many more 95-degree or hotter days and much fewer subfreezing days. This year made Hansen's predictions seemed like underestimates. For example, he predicted that in the 2010s Memphis would have on average 26 days of more than 95 degrees. This year there were 47.