Last year's extreme weather across the U.S. — 2011 was the most expensive year ever for natural disasters — is raising concern among scientists and policymakers about the nation's ability to withstand a shifting climate.
Damage from tornadoes, floods, droughts, hurricanes and wildfires caused more than $200 billion in losses and 1,000 deaths across the nation last year. Florida escaped major damage, but saw record high temperatures over the summer, after a much colder than normal winter.
The conversation about climate change has to move beyond debates about greenhouse gases to discussions about making homes and infrastructure more resilient to weather, said Margaret Davidson, director of the Coastal Services Center for the National Oceanic and Atmospheric Administration.
Communities must reduce their vulnerabilty, she said during a forum on adapting to climate change at the American Meteorological Society meeting here.
Recent trends show the cost of natural disasters escalating while the government's financial ability to deal with those losses shrinks. Climate scientists anticipate an uptick in extreme weather as the global climate warms.
"You can see there's a train wreck coming and it has to do with Mother Nature," Davidson said.
In communities where disasters, such as floods and storm surge, occur frequently, the knee-jerk reaction is to rebuild the same roads and bridges that existed before and bigger, more expensive homes. Those "stupid" decisions cost the nation, Davidson said, adding that 70 percent of repetitive losses covered by the Federal Emergency Management Agency are in coastal counties.
Floods this year caused some of the most dramatic and costly damage. Hurricane Irene, which brought devastating and record-breaking floods to Vermont, hit the East Coast three times. The storm killed 45 people and inflicted $7.3 billion in damage. The cost of recovery caused tension in Congress when some leaders balked at sending relief to affected communities.
The Midwest and Northern Plains saw record floods from snowmelt and torrential rainfall that swelled the Mississippi, Ohio and Missouri Rivers.
Seven states in the Northeast and the Ohio Valley had their wettest year on record, with some seeing rainfall of up to 8 inches above normal, said Jake Crouch, a physical scientist with the National Climactic Data Center, a federal agency that publishes and annual State of the Climate report.
Meanwhile, the southern tier of the nation baked in drought. Texas experienced its greatest drought on record and saw raging wildfires that destroyed 1,500 homes. Nearly 60 percent of the nation plunged into drought last year, also breaking a record.
In 2011, 58 percent of the nation was either extremely wet or extremely dry, the highest percentage ever, according the report.
It was also a year of devastating tornadoes across the Midwest and the Southeast. The spring storm season sent waves of cold fronts colliding with the warm, moist atmosphere over the Southeast. The severe storms triggered 1,155 tornadoes, killing more than 300 people and causing $20 billion in damage.
The nation saw a total of 14 natural disasters that cost more than $1 billion each, breaking another new record, and underscoring the effect of climate extremes on people, Crouch said.
While scientists cannot blame any single disaster on climate change, they can point to trends and make comparisons between what they see and what changes are predicted in a warmer world. Last year fit with expectations that a warmer Earth would bring much more rain to the Northeast, drought to the Southern Plains, warmer than normal temperatures in the high latitudes, such as those of Norway and Siberia, and shrinking sea ice.
For the U.S., extreme drought and rainfall were likely a combination of climate change and regular climate variation related to sea surface temperatures in the Pacific, Crouch said. Last year was dominated by La Niña, a weather pattern triggered by cooler than normal Pacific seas.
An interesting obversation that Crouch noted, however, was that La Niña years tend to be cooler globally. Last year was the 11th warmest year on record and the warmest La Niña year on record.