PARIS - A PREDICTED slowdown in Atlantic Ocean currents will cause sea levels along the US north-east coast to rise twice as fast as the global average, exposing New York and other big cities to violent and frequent storm surges, according to a new study.

Sea levels vary across regions by up to 24cm, influenced in part by powerful currents that coarse around the globe in a pattern called the thermohaline circulation.

In the Atlantic, warm water moving north along the surface from the Gulf of Mexico helps temper cold winters in western Europe and along the US east coast, while frigid Arctic waters run south along the bottom of the sea.

The UN's Intergovernmental Panel on Climate Change (IPCC) concluded in early 2007 that expanding ocean water driven by climate change will drive up sea levels, on average, anywhere from 18 to 59cm by 2100, depending on how successful we are at slashing greenhouse gas emissions.

This rising water mark will erase several island nations from the map, and is likely to cause devastation in Asian and African deltas home to tens of millions of people.

Rapid sea level increases would put cities such as New York, Boston, Baltimore and Washington D.C. at significantly greater risk of coastal hazards such as hurricanes and intense winter storm surges.

A study released last year by the Cambridge, Massachusetts-based Union of Concerned Scientists showed that, due to rising sea levels, once-in-a-century storms would occur on average every 10 years by 2100.

A large belt of around the tip of Manhattan - including Wall Street - would have a 10 per cent chance of flooding in any given year, it concluded. -- AFP