Sea-level rise ‘hotspots’ could threaten East Coast cities: USGS

Sea-level rise ‘hotspots’ could threaten East Coast cities: USGS

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According to a press release from the United States Geological Survey, a new report of measurements of sea level on the Atlantic coast of North America reveals the problem of “hotspots” of sea level rise. Rather than increasing evenly, some scientists predict that rising sea levels would be concentrated in specific areas, or “hotspots”, where conditions would emphasize sea level changes. USGS Director Marcia McNutt explains, “Many people mistakenly think that the rate of sea level rise is the same everywhere as glaciers and ice caps melt, increasing the volume of ocean water, but other effects can be as large or larger than the so-called ‘eustatic’ rise.” However, in addition to such general considerations, McNutt notes, “As demonstrated in this study, regional oceanographic contributions must be taken into account in planning for what happens to coastal property.”

According to a study published in Nature Climate Change, the 1000 kilometer long stretch of Atlantic coast extending north from Cape Hatteras is potentially just such a hotspot. If warming causes more fresh water to be released from ice caps in the arctic, scientists predict that a combination of changes in water temperature, salinity, and density in the northern Atlantic could lead to a slowing in circulation in the North Atlantic, making the North American Atlantic coast a focal point of sea level rise.

The USGS reports that 21st century sea level increases might reach 8.1 to 11.4 inches. In addition to being of concern in itself, the release also notes that such increases in sea level increase the danger to coastal cities of the temporary sea level rise associated with storms. Asbury Sallenger, lead author of the study, says, “Ongoing accelerated sea level rise in the hotspot will make coastal cities and surrounding areas increasingly vulnerable to flooding by adding to the height that storm surge and breaking waves reach on the coast.” Sallenger adds, “Cities in the hotspot, like Norfolk, New York, and Boston already experience damaging floods during relatively low intensity storms.”

The authors of the study made use of tide-gauge measurements along the North Atlantic coast and analyzed them for signs of changing sea levels. The authors of the study are affiliated with the St. Petersburg Coastal and Marine Science Center of the USGS, and the report was published as a letter in Nature Climate Change online.

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