A huge storm barrels down on the United States, wreaking havoc with punishing winds, record flooding, heavy snowfall and massive blackouts. Is the main culprit climate change or a freak set of coincidences?

Sandy wiped out homes along the New Jersey shore, submerged parts of New York City, and dumped snow as far south as the Carolinas. At least 50 people were reported killed in the United States, on top of 69 in the Caribbean, while millions of people were left without power.

Some scientists say that the key to Sandy’s impact may be an extremely rare clash of weather systems, rather than the warmer temperatures that scientists have identified in other hurricanes and storms.

“It’s a hybrid storm, which combines some features of tropical hurricanes with some features of winter storms, that operate on quite different mechanisms,” said Kerry Emanuel, a professor of Atmospheric Science at Massachusetts Institute of Technology.

While Emanuel said that there is a clear link between climate change and general trends toward more intense tropical hurricanes, in the case of Sandy more long-term study is required to determine whether climate change played a major role.

Other scientists say climate change likely aggravated whatever unique circumstances produced Sandy. They include the global warming that has caused ocean temperatures and sea levels to rise, contributing to more destructive flooding and other damage.

“Sea level rise makes storm surges worse and will continue to do so in the future,” said Stefan Rahmstorf, professor of physics of the oceans at the Potsdam Institute for Climate Impact Research in Potsdam, Germany.

World sea levels have risen by 20 centimeters (8 inches) in the past 100 years, a trend blamed on melting ice and expanding water in the oceans caused by rising temperatures. “Every centimeter adds to damage,” Rahmstorf said.

Kevin Trenberth, a senior scientist in the Climate Analysis Section at the National Center for Atmospheric Research in Boulder, Colorado, said the jury was still out.

“There are clearly changes in the environment that all of these storms are occurring in,” he said. As for Sandy, however, a lot of the weather conditions that lined up were due to a “crap shoot.” A hybrid storm can be an explosive storm, “what we might call a meteorological bomb,” without the influence of climate change.

Thomson Reuters