Hurricane Sandy began life as a tropical storm in the Caribbean on Oct. 22 and was upgraded to a hurricane on Oct 24. It made its first landfall on Jamaica and headed north. On Oct. 28, Sandy began to head west, putting it on track to make landfall on New Jersey, since a high pressure-system over Canada had blocked Hurricane Sandy's northern path. Additionally, the jet stream, an air current that typically flows from west to east, had shifted so that it was flowing southeast to northwest. This created a vacuum above the storm and drew Sandy's air upward, thus allowing the hurricane to maintain its shape and circulation, and even to strengthen. The full moon was yet another factor, since it caused high tides to be higher than normal.
Stu Ostro, the senior meteorologist of The Weather Channel described Sandy as "a meteorologically mind-boggling combination of ingredients coming together." It was "a warm-core tropical cyclone embedded within a larger nor'easter-like circulation; and eventually tropical moisture and arctic air combining to produce heavy snow in interior high elevations." Its hybrid nature and its size (1,040 mi in diameter) earned it the nickname "Frankenstorm." It caused 8.1 million power outages in 17 states. Sandy also brought a record storm surge of almost 14 feet to downtown Manhattan.
The big question, of course, is whether or not global warming had an impact on Hurricane Sandy. Kevin Trenberth, former head of the Climate Analysis Section at the U.S. National Center for Atmospheric Research, has argued that "all weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be."
The Atlantic Ocean is now 5°F (3°C) warmer than average. Warmer water increases the likelihood of stronger storms further north-- and Sandy's effects were felt as far north as Canada. In addition, the warmer the ocean's surface temperature, the more evaporation there is and the heavier the rainfalls are. Each 1°C rise in temperature causes atmospheric water vapor to increase by seven percent.
Global warming is also causing glaciers and ice caps to melt, which in turn causes sea levels to rise. In the Mid-Atlantic , the coastal seas have risen by roughly eight inches since 1900-- and about a foot in New York Harbor. Higher sea levels can exacerbate both storm surges and flooding. That's true of small storms as well as big ones.
The worst news is that Sandy is just the beginning-- and that the U.S. is particularly vulnerable to weather-related disasters. The reinsurance company Munich Re conducted a study covering the years from 1980 to 2011 using 30,000 records, and found that North America, of all the continents, experiences the most weather-related catastrophes. One reason, besides climate change, is that North America, which is a large continent that extends from the tropics to arctic areas, does not have a mountain range that runs east to west, which means there is nothing to separate cold air from hot air. Such a mountain range would have hypothetically kept Hurricane Sandy from combining with the Canadian nor'easter, and the two storms would have likely been a lot smaller. Munich Re also notes that North America is prey to every type of hazardous weather: hurricanes, thunderstorms, blizzards, tornados, droughts, and floods. Climate change has been definitively linked to many of these.
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