Meltwater could prove problematic (Image: Nick Cobbing/Rex Features)

More fresh water isn’t always a good thing. The volume of fresh water gushing into the Atlantic from Greenland has increased in the past few decades. The water will interfere with Atlantic currents and may even reduce the ocean’s ability to store carbon.

“Greenland has been losing increasing amounts of mass,” says Jonathan Bamber of the University of Bristol in the UK. What had been unclear was how much of that was due to losing water to the ocean, as opposed to factors like reduced snowfall.

Bamber and his colleagues have reconstructed the freshwater losses from Greenland from 1958 to 2010. The losses have accelerated since the early 1990s, particularly around the southern tip of the island. The south-east has seen losses rise by 50 per cent in less than 20 years.


Dumping fresh water into the North Atlantic could weaken the Atlantic Meridional Overturning Circulation (AMOC), the vast “conveyor belt” current that carries warm tropical water to northern Europe. It has been suggested that Europe will get colder as a result, but that is unlikely to happen, at least in the next few decades. “That was all blown out of proportion,” says Ruth Curry of the Woods Hole Oceanographic Institution in Massachusetts.

The polar oceans are among the world’s most important carbon sinks, taking in carbon dioxide from the air and trapping it in their depths – and that could change as a result of the freshwater flux. Curry says Greenland’s fresh water will remain at the surface, since the weakened AMOC will be slow to carry it to the bottom. That also means that once this fresh water has absorbed as much carbon dioxide as it can hold, it will not be replaced at the surface by carbon-dioxide-free water that could absorb more of the gas.

“If you slow the AMOC, you’re decreasing the ability of the ocean to take up carbon dioxide,” Curry says. Weakening the carbon sink like this could speed up global warming even further.

Journal reference: Geophysical Research Letters, doi.org/jg6