WASHINGTON -- As 2012 began, winter in the United States went AWOL. Spring and summer arrived early with wildfires, blistering heat and drought. And fall hit Long Island and the eastern third of the country with the ferocity of superstorm Sandy.
This year's weather was deadly, costly and record-breaking everywhere -- but especially in the United States. If that sounds familiar, it should. The previous year, 2011, also was one for the record books.
"We've had two years now of some angry events," said Deke Arndt, U.S. National Climatic Data Center monitoring chief. "I'm hoping that 2013 is really boring."
In 2012, many of the warnings scientists have made about global warming went from dry studies in scientific journals to real-life video played before our eyes: Record melting of the ice in the Arctic Ocean. U.S. cities baking at 95 degrees or hotter. Widespread drought. Flooding. Storm surge inundating swaths of New York City.
All of that was predicted years ago by climate scientists, and all of it happened in 2012.
Globally, five countries this year set heat records, but none set cold records. The year is on track to be the warmest year on record in the United States. Worldwide, the average through November suggests it will be the eighth warmest since global record-keeping began in 1880.
America's heartland lurched from one extreme to the other. Historic flooding in 2011 gave way to devastating drought in 2012.
"The normal has changed, I guess," said U.S. National Weather Service acting director Laura Furgione. "The normal is extreme."
The most troubling climate development this year was the melting at the top of the world, said Michel Jarraud, secretary-general for the World Meteorological Organization. Summer sea ice in the Arctic shrank to 18 percent below the previous record low. Changes in the Arctic alter the rest of the world's weather and "melting of the ice means an amplifying of the warming," Jarraud said.
There were other weather extremes no one predicted: A European winter cold snap killed more than 800 people. A bizarre summer windstorm called a derecho in the U.S. mid-Atlantic left millions without power. Antarctic sea ice inched to a record high. More than a foot of post-Thanksgiving rain in the western United States. Super Typhoon Bopha, which killed hundreds in the Philippines, was the southernmost storm of its kind.
Not everything is connected to man-made global warming, climate scientists say. Tornadoes have no scientifically discernible connection. The East Coast superstorm will be studied to see whether climate change is a cause, but scientists say rising sea levels clearly worsened flooding. They are more convinced that summer's heat waves are linked to global warming.
These are "clearly not freak events" but "systemic changes," said climate scientist Stefan Rahmstorf of the Potsdam Institute in Germany.