After years of disagreement, climate scientists and hurricane experts have concluded that as the climate warms, there will be fewer total hurricanes. But those storms that do develop will be stronger and wetter.
Sandy took an unprecedented sharp left turn into New Jersey. Usually storms keep heading north and turn east harmlessly out to sea. But a strong ridge of high pressure centered over Greenland blocked Sandy from going north or east, according to the National Hurricane Center.
Jennifer Francis of Rutgers University, an expert in how a warming Arctic affects extreme weather patterns, said recent warming in the Arctic may have played a role in enlarging or prolonging that high pressure area. But she cautioned it's not clear whether the warming really had that influence on Sandy.
While components of Sandy seem connected to global warming, "mostly it's natural, I'd say it's 80, 90 percent natural," said Gerald North, a climate professor at Texas A&M University. "These things do happen, like the drought. It's a natural thing."
On Tuesday, both New York Mayor Michael Bloomberg and Gov. Andrew Cuomo said they couldn't help but notice that extreme events like Sandy are causing them more and more trouble.
"What is clear is that the storms that we've experienced in the last year or so, around this country and around the world, are much more severe than before," Bloomberg said. "Whether that's global warming or what, I don't know. But we'll have to address those issues."
Cuomo called the changes "a new reality."
"Anyone who says that there's not a dramatic change in weather patterns I think is denying reality," Cuomo said. "I told the president the other day: 'We have a 100-year flood every two years now.'"
For his published research, Oppenheimer looked at New York City's record flood of 1821. Sandy flooded even higher. This week's damage was augmented by the past century's sea level rise, which was higher than the world average because of unusual coastal geography and ocean currents. Oppenheimer walked from his Manhattan home to the river Monday evening to watch the storm.
"We sort of knew it could happen, but you know that's different from actually standing there and watching it happen," Oppenheimer said from a cell phone. "You don't really imagine what this looks like until you see it."