Recent Tornadoes a Result of Climate Change?

With the damage caused last week by the massive storm system responsible for deadly tornadoes, including the one that struck Moore, Okla., some media outlets have raised the issue of climate change, investigating whether there could be a link between recent tornado activity, and this storm system in particular, and a warming climate. 

A “News Watch” article on National Geographic's website, for example, opens, “Hours after a powerful tore through an Oklahoma suburb, killing dozens, some renewed speculation about such storms' connection to climate change.” 

A CNN headline declares, “No Evidence Global Warming Spawned Twister.” 

And an Associated Press article appearing on Star-Ledger – NJ.com asks, “Oklahoma Tornado: Is Global Warming to Blame?” 

The question has spilled over to Congress, where at least one federal legislator, Rhode Island Democratic Senator Sheldon Whitehouse, attempted to make the link between the storm system and climate change on the Senate floor, according to the New York Daily News. Whitehouse said, in a jab at his Republican counterparts who contest a human role in changing climate, “When cyclones tear up Oklahoma and hurricanes swamp Alabama and wildfires scorch Texas, you come to us, the rest of the country, for billions of dollars to recover. And the damage that your polluters and deniers are doing doesn't just hit Oklahoma and Alabama and Texas. It hits Rhode Island with floods and storms. It hits Oregon with acidified seas. It hits Montana with dying forests. So, like it or not, we're in this together.” 

Whitehouse has since apologized, stating that he regrets the timing of his speech, and he pledged to assist those in need in Oklahoma. 

On the other side of the aisle, Oklahoma Republican Senator Jim Inhofe charged in an interview with Newsmax that people trying to link the tornado to climate change “do a great disservice to those who have experienced this tragedy,” adding that they are trying to exploit a tragedy to further an agenda. 

Howard Altschule, president and forensic meteorologist at Forensic Weather Consultants, LLC, tells PC360 the weather pattern that spawned the Moore tornado is a fairly common one for this time of year. “We are climatologically in the most active part of tornado season for tornado alley, “he says. “It spans the two weeks before and the two weeks after June 1.” 

He says every so often, large and violent tornadoes like the one that hit Moore will occur, “but they usually stay out in unpopulated areas of Texas, Oklahoma and Kansas. What's different here is that a large, violent and long-track tornado went over populated areas, hit occupied schools, a hospital, homes and other buildings.” 

But Altschule does note, “There's no doubt that these large, violent and long-track tornadoes are occurring more often than they have in the past.” 

Catastrophe modeler Eqecat, which said the recent storm activity could cause up to $5 billion in insured losses, says current climate-warning models “do not necessarily imply increased thunderstorm activity.” 

The firm explains, “The warmer, moister atmosphere forecast by the climate-warming models do provide more fuel for thunderstorms, but thunderstorms also need wind shear to produce strong tornadoes and it is not yet clear whether average wind shear will increase in tornado-prone regions and seasons, with the current climate models implying a decrease in average wind shear.” 

The National Geographic article says researchers agree that climate change will increase the likelihood of extreme weather events, but cannot say how this will impact tornado activity. The article quotes Michael Wehner, a climate researcher at the Lawrence Berkeley National Laboratory, as saying, “The short answer is, we have no idea. The reason I'm optimistic that we can get somewhere on this is that supercomputing technology is driving this very hard. We're just getting into the sweet spot for these kinds of issues, with the largest mainframes that money can buy.” 

The NJ.com and CNN articles agree. The CNN article quotes J. Marshall Shepherd, climate change expert and professor at the University of Georgia, as saying, “This tornadic storm, in my view, probably would have happened irrespective of whether there's climate change or not. The question is: Are we increasing the risk and probability of more extreme events in general as our climate differs?” 

A PC360 feature on climate change notes that some in the industry are preparing for a “new normal” of increased storms and therefore more and more intense tornadoes.  

Richard Dixon, the group head of catastrophe research at Hiscox and a scientist with a Ph.D in meteorology from Reading University in the U.K., says, “We're looking at a warmer planet, which means more energy for more intense thunderstorms.”  

Peter Höppe, head of Munich Re's Geo Risks Research/Corporate Climate Centre, adds, “The increase in the intensity of thunderstorm-related events—hail and tornadoes—is already happening. The increase of normalized losses over the last 40 years cannot be explained by higher property values and greater exposures alone. Warming oceans means more evaporation, which means more water in the atmosphere—which creates more favorable conditions for causing bigger thunderstorms. This is clearly backed by climate-science research and meteorological data. The chain of evidence is there that we can say we have the first footprint of global warming in more severe convective storms.”