Our first blog on Sandy observed that based on wind strength it was classified as a Category 1 Hurricane. There have been many Category 1 hurricanes over the last two centuries, and a number of these hurricanes have come ashore in the North Eastern United States. So it would not be correct to say that Sandy was “caused” by global warming. However global warming contributed to the impact of Sandy on the New Jersey-New York coastal areas in several ways.
First, because of global warming ocean levels have risen by approximately a foot along the US Eastern Seabord. This increase unquestionably was a factor in the height of the storm surge that caused such flooding on the New Jersey coast and in New York City.
Secondly, the ocean temperatures off the US East coast were 2 degrees higher than normal. Heat is the fuel for hurricanes, so Sandy might otherwise have reverted to below hurricane strength.
Would reduced wind speeds and reduced storm surge have lessened the impact? Yes, but it is a matter of conjecture to what degree the damage would be significantly reduced.
Thirdly, Sandy was redirected from the normal track of hurricanes, which takes them to the North and East of the US coast. Sandy was stalled over the Eastern seaboard by a high pressure system centered over Greenland. Some climatologists theorize that a warming Arctic is disrupting the jet stream that has restricted the influence that these systems have on the East Coast of North America.
As we suggested: this phenomenon that stalled Sandy has happened before. In the future it will happen more frequently and more erratically.
In the face of such devastation public opinion seems to be tiring of the debate over details of causation. The US people know that extreme weather conditions are now a continuous risk, and not a once-in-a-hundred-years event. The only sensible explanation provided by reasonable people who know the subject is probably the answer, even if this explanation and the scientific reasoning are difficult for the average person to understand.
In the words of New York State Governor, Andrew Cuomo:
“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.’”
(Information from this Blog comes from articles in the Washington Post and the Website Think Progress)