US East Coast faces rising seas as crucial Atlantic current slows

The weakening of the Atlantic Meridional Overturning Circulation (AMOC) is boosting the sea level along the New England coast on top of sea level rise from melting ice, adding to flooding

The slowdown of a major current in the Atlantic Ocean is boosting the sea level and associated flooding in the Northeast US, on top of the already-rising sea level due to climate change. A total collapse of this Atlantic Meridional Overturning Circulation (AMOC) as the planet warms could raise the sea level even further.

“If the AMOC collapsed, this would dramatically increase the flood frequency along the US coast, even in the absence of strong storms,” says Liping Zhang at the Geophysical Fluid Dynamics Laboratory of the US National Oceanic and Atmospheric Administration (NOAA) in New Jersey. “Even partial weakening [of the current] can already have substantial impacts.”

Melting ice sheets and warmer water due to human-caused climate change are leading to a rise in average sea level, but the rate of sea-level rise isn’t the same everywhere. For instance, some coastal land is sinking, speeding the relative rate of sea-level rise in those areas. Local sea level is also shaped by how heat, water and salt circulate in the ocean, with warmer and fresher water taking up more space than colder, saltier water.

Cover photo:  The AMOC is a system of ocean currents that circulates water within the Atlantic Ocean