Is climate change responsible for deadly U.S. tornadoes?

Mitch Potter in the Toronto Star: Giant tornadoes that killed at least 290 people in six U.S. states on Wednesday could provide a treasure trove of answers to scientists searching for evidence tying the outbreaks to climate change.

…While a raft of climate science points to a stormier future involving more frequent and possibly more severe hurricanes, researchers have yet to factor tornadoes into climate-change predictions with any certainty.

Theories abound, however, including a 2009 University of Georgia study that suggested climate change could in fact bring about fewer tornadoes in the southeastern United States, which sustained the worst of the Tuesday’s devastation.

But Purdue University climatologist Dev Niyogi, one of the co-authors of the Georgia study, cast doubt on even those findings in an interview Wednesday. Niyogi, like many climate experts, described with awe the sheer rarity of complex conditions that made Tuesday’s storm formations unlike anything the region has seen since the 1970s “The simple answer is we don’t really know whether climate change is going to cause more tornadoes. The jury is still out,” Niyogi told the Toronto Star.

… Niyogi attributes much of the swarming tornadoes of 2011 to “a La Nina spring, which is what we’re in right now. I suspect both the flooding and the extreme storms points to a seasonal variability (La Nina) signature more than a climate-change signature.”…

A radar image of a supercell thunderstorm about to pass through Raleigh, North Carolina during the Mid-April 2011 tornado outbreak.