Sea level rise: Global warming impact hits home

With a sea level 7.5 feet above standard high tides, a flood map shows large areas of Greater Boston under water, including Logan International Airport, half of South Boston, and most of Back Bay, East Cambridge and the South End. In October 2012, Hurricane Sandy brought 10-foot storm surges to New York City at high tide, inundating the metropolitan area, knocking out two airports and causing flood damage estimated in billions of dollars. /Boston Harbor Association image

A recent research effort attempted to forecast areas likely to experience the most severe impact from 21st century sea level rise linked to global warming. The primary finding of the research is that sea level rise will not be uniform around the globe.

The Potsdam Institute for Climate Impact report predicts the worst sea level rise in the next 100 years will hit coastal areas in low latitudes such as the Western Pacific Ocean and Indian Ocean, including India, Bangladesh, Japan, Argentina, Australia and South Africa.

There are variables that will affect the study's conclusions. A key factor will be the relative melting of the Greenland and Antarctic ice sheets. For the North Atlantic Ocean, the rate of Greenland ice melt will largely determine the severity of sea level rise. Ironically, while Greenland is much closer to where I live in New England than Antarctica, the gravitational effect of losing the Greenland glaciers will partially offset the sea-level impact of ice melt pouring off Greenland into the North Atlantic.

Hurricane Sandy's pummeling of New York and New Jersey in October 2012 as well as Boston Harbor Association flood maps released in February 2013 illustrate a more stark reality: The sea level rise and increase in severe storms that we have already experienced from global warming pose an immediate threat to the vast majority of coastal cities.

Most of Boston's Inner Harbor neighborhoods would be underwater with a 7.5-foot increase in sea level above an average high tide. An increase in hurricanes and nor'easters makes this kind of flooding a prime climate change risk factor for cities along the U.S. East Coast. /Boston Harbor Association image