Abrupt Climate Change

New Study Reports Large-scale Salinity Changes in the Oceans
(Enlarged figure)

Tropical Atlantic surface waters have become saltier...
Tropical and subtropical Atlantic waters have become dramatically saltier over the past 40 years, especially in the past decade, scientists reported today in Nature. Global warming may be intensifying evaporation, adding more fresh water vapor to the atmosphere and leaving tropical oceans relatively saltier. The evidence suggests that recent climate changes may be accelerating the fundamental planetary system that transports and cycles fresh water around the globe, which could trigger or amplify other significant climate changes.

...while North Atlantic deep water have become fresher. Over the same 40-year period, deep waters have become less salty in critical North Atlantic locations, where salty, dense waters sink to drive the global ocean circulation system called the Ocean Conveyor. If the North Atlantic becomes too fresh, its waters could stop sinking, and the Conveyor could slow down, causing widespread climate disruptions. This freshening trend has accelerated in the past decade, and a mass of fresher deep water is spreading southward.

Data from Ruth Curry. Illustration İRuth Curry and Jack Cook, Woods Hole Oceanographic Institution.