vrijdag 16 september 2011

Sea level rise



Image: Storm surge from the 1938 hurricane at the Battery, New York City | Credit: NOAA/NWS Historic Collection.

New York is one of the most vibrant and rich cities in the world. It was the first megacity in 1950. But at same time the city is very vulnerable to storms and the rising current due to the climate change.  Many parts of New York city lay just a few feet above sea level. Flooding of the subway and airport can easily disconnect the city from the world. By 2050 the water will rise 30 to 70cm and by 2080 60 to 140cm. 

Recently the subway was shut down one day and a half before hurricane Irene threatened the region.
“New York's subway system, which carries 7 million riders daily and operates the largest fleet in the world, had never closed due to weather.”

“Airlines canceled more than 9,000 flights for the weekend and another 250 on Monday.”

“More than 1 million people evacuated the New Jersey shore areas via roads over a 24-hour period.”

“New York authorities said they could close the George Washington Bridge, depending on Irene's winds. Other New York City suspension bridges could also close.”

“New York harbor was emptied of ships.”



Image: A message is left for Hurricane Irene on one house | http://www.csmonitor.com/USA/2011/0826/Hurricane-Irene-carries-threat-of-inland-floods-not-just-coastal-surge-VIDEO
 
“Jianjun Yin, a climate modeler at the Center for Ocean-Atmospheric Prediction Studies (COAPS) at Florida State:

Considering that much of the metropolitan region of New York City is less than 16 feet above the mean sea level, with some parts of lower Manhattan only about 5 feet above the mean sea level, a rise of 8.3 inches in addition to the global mean rise would pose a threat to this region, especially if a hurricane or winter storm surge occurs, Yin said.

Potential flooding is just one example of coastal hazards associated with sea-level rise, Yin said, but there are other concerns as well. The submersion of low-lying land, erosion of beaches, conversion of wetlands to open water and increase in the salinity of estuaries all can affect ecosystems and damage existing coastal development.

Although low-lying Florida and Western Europe are often considered the most vulnerable to sea level changes, the northeast U.S. coast is particularly vulnerable because the Atlantic meridional overturning circulation (AMOC) is susceptible to global warming. The AMOC is the giant circulation in the Atlantic with warm and salty seawater flowing northward in the upper ocean and cold seawater flowing southward at depth. Global warming could cause an ocean surface warming and freshening in the high-latitude North Atlantic, preventing the sinking of the surface water, which would slow the AMOC.”



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