Climate change has, on average, raised the surface of the world’s oceans in recent decades by melting glaciers and causing seawater to expand as it warms. But the rise has not been uniform, just like the increase in ocean temperature. As noted in prior posts, both temperature increases and rising sea levels have happened at different speeds in different places, due to (among other things) wind patterns, ocean currents, and other regional factors that influence oceanic surfaces.
Researchers studied the East Coast using 60 years of data collected by sensors floating in the Atlantic Ocean. From 1980 to 2009, sea levels along about 1,000 kilometers (roughly 620 miles) of coast rose faster than during the time period from 1950 to 1979, gaining about 2 millimeters (0.08 inches) per year, or about three to four times the average global acceleration.
If this acceleration continues at its current rate, New York City would be on track for up to 29 centimeters (about 11.5 inches) of sea level rise by 2100, an increase in line with previous predictions from a simulation based on probable climate change scenarios. (See prior posts regarding variability in predictions by climate models and solar factors that may be influencing global warming rates.)
Long-term climate trends may have created this hot spot by changing ocean currents. With the atmosphere heating, parts of the North Atlantic have warmed. Computer simulations suggest the decreasing density of these waters could weaken the Gulf Stream and North Atlantic Current which carry warm waters and salt northward and keep Europe relatively warm. (See prior posts on the water temperature hot spots found in oceans about Antartica, which conforms to some climate model predictions.)
Critics note that this theory lacks the support of actual measurements that show a waning of ocean circulation. Some scientists credit the sea level speedup to weather patterns that could soon reverse. (As noted in prior posts, this contrasts with the Antartic hot spots for which there are actual measurements over time.) Critics note that the recent trend may reflect fluctuations in pressure or temperature that oscillate over decades; critics note that sea levels along the East Coast fell before 1960, and may very well do so again.
As they say, we shall see. The paper can be found at: http://www.nature.com/ngeo/journal/v2/n4/full/ngeo462.html.
Ironically, shortly before this paper was published, the North Carolina Senate proposed legislation to ban predictions of sea level increases. God forbid that science should have any First Amendment rights. See http://www.nature.com/news/us-northeast-coast-is-hotspot-for-rising-sea-levels-1.10880.
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