Superstorm Sandy, a “perfect storm” that was caused by anunusual combination of seasonal weather phenomena converging abovethe Northeast, has stirred some conversation in the media aboutwhether the storm was caused, or made worse, by climate change.

Scientists have long warned about the risk of a deadly hurricaneover the Tri-State area, which would suggest Sandy could be anexpected weather event. But recent studies, including a report co-authored by MIT climate scientist Kerry Emanuel inFebruary 2012, note that climate change could combine withthe effects of storm surge to cause 100-year-flooding tooccur every two decades in New York, suggesting that an event likeSandy may be more than just a long-expected storm.

Insurance, climate and modeling experts weigh in on the roleclimate change may have played in Superstorm Sandy.

Robert Detlefsen, Ph.D., vice president ofpublic policy, National Association of Mutual InsuranceCompanies: “The problem that arises when we starttalking about whether climate change ought to be considered aseparate determining factor in the likelihood of extreme weatherevents is that nobody knows how particular geographic regions willbe affected in the near-term. I would question the assertion ofpeople who have definitively stated that Sandy was caused byclimate change as there are many factors responsible for causingany weather event.

“However, one hopes that that we have learned our lesson andwill take further steps to determine the laws regulators mustadjust in order to allow coverage to continue being written inat-risk areas. The North Atlantic seaboard will be hit by majorwindstorms in the future, but our society has a short memory, so asother issues come to dominate the news insurers hope policymakersdon't lose sight of the need to address what came to the fore whenSandy came to town.”

Tom Larsen, senior vice president and productarchitect, Eqecat: “Were the effects of Sandy exacerbatedby climate change? Yes, absolutely. Was Sandy caused by climatechange? That remains unclear. It certainly wasn't predicted by ourmodels. There is speculation that steering pressure coming from thenorth was linked to melting Arctic sea ice, however there isinsufficient data- compelling but not convincing- to give us greatcertainty about it.

“Sea level rise due to climate change does influence how far astorm surge travels. Sandy set a new record at the Battery Parkindicator for the first time in 50 years with a 14 foot surge, orfour feet higher than the last one set by Hurricane Donna. Meltingsea ice has caused a sea change of six to eight inches, which isjust a fraction of that total shift. Also, while we did haveabnormally warm Atlantic waters at this time of year, it was justone necessary ingredient for a storm like this.”

Dr. Bob Corell, senior policy fellow, AmericanMeteorological Society: “You can't simply state thatclimate change caused Sandy, but it made her more intense. It'svery important to make the connection between weather extremes andthe warming of the planet, because warmer water contains energythat drives hurricanes.

“Cyclonic storms pick up that energy as they come across theAtlantic from the African coast on their way to the Caribbean,where measurements taken over the past several decades show thatwater surface temperature has warmed by as much as two degrees.

“That may not sound like much, but it is a huge amount of energywhen it is spread over an ocean and sucked into the atmosphere. Putanother way, we will have far more Category Three to Five stormsthan we used to. Sandy was only a Category One storm, but itcombined with two other systems that were amplified by the warmatmosphere to become the hybrid that it was.”

Cynthia McHale, insurance program director,CERES: “Many models have been created to understand NewYork City's vulnerability to sea level rise, and it has beenpredictable and predicted that at some point lower Manhattan wouldbe flooded.

“No one knew when it would be hit or how badly. There were manyfactors in play, including sea level rise and the increased risk ofintense Caribbean hurricanes due to higher ocean temperatures. Somescientists also tied in cold air coming up from the Arctic early inthe season.

“Underwriters and reinsurers think of the worst-case riskscenario and how it will affect the corporate capital for whichthey're on the line. In this case, there was enough concern to saythat there is likely to be severe, weather-related flooding downthe coast, even without concrete evidence for climate change. Andthe fact that the term is so politicized steers the industry awayfrom it without first understanding what the risks are.”

Dr. Tim Doggett, principal scientist, AIRWorldwide: “A number of factors influence how active aseason is, including sea surface temperatures and wind shear, andwhether these are affected by man-made climate change remainsuncertain. 2012 was an indeed active in terms of number of tropicalstorms that formed in the Atlantic basin, but only an averageseason in terms of the number of storms that actually made landfallin the U.S.

“While there are theories that climate change may increaselosses from natural catastrophes in certain regions of the world,as of yet, there is no definitive indication that the frequency oflandfalling hurricanes is increasing. AIR scientists have foundthat variations in Atlantic sea surface temperatures account forless than 1 percent of the variability in U.S. hurricane landfalls.Instead, mid-level steering currents, which are highly variable andunpredictable because they are determined by short-term weatherpatterns, are responsible for some 80% of the variation in stormtracks.”

Kerry Emmanuel, climate scientist, MIT (from an interviewwith Slate): “Sandy is an exampleof what we call a hybrid storm. It works on some of the sameprinciples as the way hurricanes work but it also works on the sameprinciples as winter storms work. Hurricanes and winter storms arepowered by completely different energy sources. The hurricane ispowered by the evaporation of sea water. Winter storms are poweredby horizontal temperature contrasts in the atmosphere. So hybridstorms are able to tap into both energy sources. That's why theycan be so powerful.

“My profession has not compiled a good climatology of hybridevents […] We don't have very good theoretical or modeling guidanceon how hybrid storms might be expected to change with climate. Sothis is a fancy way of saying my profession doesn't know how hybridstorms will respond to climate. I feel strongly about that. I thinkthat anyone who says we do know that is not giving you a straightanswer. We don't know. Which is not to say that they are not goingto be influenced by climate, it's really to say honestly we don'tknow.”

Chris Hackett, policy expert, director of personallines, Property Casualty Insurers Association of America(PCI):

“Rather than looking at the specific cause of any one event,events like Sandy and Irene last year drew attention to the needfor stronger building codes […] As communities look to rebuild,it's also an opportunity to revisit responsible land use policiesaround the coast- what changes could be made for when next Sandycomes through the area? It's probably not a matter of if but when,even if it doesn't occur in the next 10, 15 or 20 years.

“It's difficult to pinpoint whether any particular weather eventis related to climate change, because you don't know if it had.It's not about climate change; it's about taking care of people'sneeds. I'm not sure that models can predict 15 years ahead. We tryto work more from actual historical loss data when setting rates asopposed to projecting into the long-term future of weather eventsin any geographical area.”