By Mary Wisniewski
CHICAGO (Reuters) - Blizzards. Tornadoes. Floods. Record heat and drought, followed by wildfires.
The first eight months of 2011 have brought strange and destructive weather to the United States.
From the blizzard that dumped almost two feet of snow on Chicago, to killer tornadoes and heat waves in the south, to record flooding, to wildfires that have burned more than 1,000 homes in Texas in the last few days, Mother Nature has been in a vile and costly mood.
Climate experts point to global warming, meteorologists cite the influence of the La Nina weather phenomenon or natural variability and, in the case of tornadoes hitting populated areas, many simply call the death and destruction bad luck.
But given the variety and violence of both short-term weather events and longer-term effects like a Southwestern drought that has lasted years, more scientists say climate itself seems to be shifting and weather extremes will become more common.
"A warmer atmosphere has more energy to power storms. We've loaded the dice," said Jeff Masters, co-founder and director of meteorology for Weather Underground, Inc, speaking on Wednesday at a news conference on climate. "Years like 2011 may become the new normal in the United States in coming decades."
The year has been expensive, in terms of crops, property and lives lost. The National Oceanic and Atmospheric Administration has kept track of the cost of weather disasters since 1980, and 2011 has seen 10 separate natural disasters with economic losses of $1 billion or more, according to Chris Vaccaro, spokesman for the National Weather Service.
The previous record was nine, set in 2008. The costs go ever higher, with the nine 2011 disasters even before Hurricane Irene two weeks ago costing $35 billion, Vaccaro said.
Other years have been more expensive overall due to single events, such as Hurricane Katrina in 2005. But 2011 has already moved into the top 25 percent of the costliest years, and the hurricane season isn't half over, Vaccaro said.
The Federal Emergency Management Agency (FEMA) says it will need $5.2 billion in known disaster relief for the year that starts October 1. But that doesn't include Hurricane Irene, which caused devastating flooding in Vermont and New Jersey, and is expected to cost at least $1.5 billion in relief, FEMA says.
FIRE AND RAIN
The year began with what was called "Snowmageddon" -- heavy snows in multiple states, including the south.
Kansas got up to 40 inches in some areas in a month -- the same as a typical total for the whole winter. New York had its snowiest January on record.
Snow melt, combined with a wet spring, caused flooding on the Mississippi, Ohio, Souris and Missouri Rivers.
On the Mississippi, records set in the historic floods of 1927 and 1937 were challenged and exceeded along the nation's largest main river artery, resulting in evacuations and millions of acres of flooded farmland.
In the Missouri River valley, flow rates broke previous records, damaging levees and highways.
The year has also been the 4th deadliest tornado year in U.S. history with 546 deaths, according to the NWS.
The May 22 tornado that hit Joplin, Missouri, took 160 lives, making it the deadliest single tornado since 1947.
This summer, the country also baked under days of 100-plus degree heat, with records smashed in northern locations like Newark, New Jersey, which saw a high of 108 degrees.
Texas saw what looks to be its hottest summer, making that vast state into a tinderbox. Wildfires have scorched more than 3.6 million acres since November, fed by a drought that has caused more than $5 billion in damage to the state's farm industry.
In Oklahoma, the average statewide temperature of 86.8 degrees from June to August 31 broke the 85.2 degree mark set in 1934, according to Gary McManus, associate state climatologist. The heat killed 21 people in Oklahoma alone.
Finally, the beginning of hurricane season caused flooding in the aftermaths of Irene and Tropical Storm Lee.
The country is already on pace to break the all-time record for the number of tropical storms strong enough to merit names, Masters said.
Many years have extreme weather events. Older Americans may recall the "Dust Bowl" of the 1930s, or the bitter Midwest winters of the late 1970s.
Judith Curry, a climate scientist at Georgia Tech, noted in a blog post this week that active hurricane seasons, heavy snowfalls, and floods and severe drought in Texas are reminiscent of the 1950s.
"Natural variability is a plausible explanation for variations in extreme frequency and also clustering of events," Curry said.
While most climate scientists agree that human actions are causing global warming and climate change, not everyone does.
Republican presidential front-runner Rick Perry said last month he does not believe in man-made global warming, calling it a scientific theory that had not been proven. Other political conservatives have questioned evidence of man-made climate change and government plans that could slow it.
Katharine Hayhoe, an atmospheric scientist at Texas Tech University, said policy is not black and white, and there has to be debate over policies to address climate change.
But policy opinions are one thing and scientific facts another, she said, adding that she is troubled to see more of the general public doubting climate change even as more scientific evidence piles up to support it.
"The evidence is what the planet is telling us," Hayhoe said. "These are not political opinions."
(Writing by Mary Wisniewski, additional reporting by Steve Olafson in Oklahoma City; Editing by Peter Bohan)