Not too long ago, climate scientists faced the daunting task of convincing skeptics that human-caused global warming really does exist. Today, nearly all Canadians accept the reality of climate change.

So when a catastrophic weather event like Superstorm Sandy upends lives, climatologists find themselves in an odd position: dousing suspicion that global warming is directly to blame.

“Every time there is a monster storm like this, people think it’s coming out of our tailpipes and smoke stacks,” says David Phillips, Environment Canada senior climatologist.

But weather, scientists constantly remind us, is not the same as climate. “I say that all the time, and it doesn’t seem to make a difference,” says Kerry Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology.

Weather is what’s happening outside the window right now, while climate is how the atmosphere behaves over time. No single weather event — a hurricane, a blizzard, a hot day — can be attributed to anthropogenic climate change, which has been gradually warming the atmosphere over more than a century.

Yet researchers are slowly starting to discover the ways that a warming planet can affect the activity of tropical storms worldwide. Many unanswered questions remain, but what we do know is “not particularly good news,” says Emanuel.

Tropical cyclones, which are also called hurricanes or typhoons, require warm sea surface temperatures in order to form. Over the past several decades, sea surface temperatures in most tropical ocean basins have increased by up to half a degree Celsius. And the most likely cause of that temperature increase is greenhouse gases.

Computerized climate models, coupled with researchers’ observations, have shown that globally, the frequency of intense storms — Category 4 or 5 — is increasing.

Yet those observations can’t be extrapolated to specific places or times, like the 2012 Atlantic hurricane season that Sandy belongs to.

“When it comes to anything regional … the models are all over the place,” says Emanuel. “There will be places where the intensity goes down and other places where it goes up.”

Researchers may be able to answer these questions one day, but for the time being there just “aren’t enough scientists to do all the work,” says Emanuel.

Complicating matters is that Sandy is a hybrid superstorm. Shortly before making landfall in New Jersey, she merged with an existing land-based winter storm to become a post-tropical cyclone, meaning her energy source had changed. (Some news outlets mistakenly reported that the hurricane had been “downgraded,” when in fact Sandy remained just as potent.)

Researchers know even less about the interaction between hybrid storms and climate change, says Emanuel.

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Yet several of Sandy’s features could become the new norm as atmospheric and ocean temperatures continue to rise. Hurricanes are increasingly bringing more rainfall, says Emanuel, since warmer water leads to more evaporation.

And hurricanes are creating bigger storm surges. Sandy deluged New York City with a surge nearly four metres high in places, breaking records and causing devastation to property and infrastructure like subways.

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