We regularly encounter stories about how the AMOC, or Atlantic Multidecadal Overturning Circulation, is on the verge of shutting down due to global warming, which will throw the global climate into complete chaos including plunging Europe into a deep freeze. Regularly as in almost weekly. And the idea, beyond beating us into submission by repetition, is that warming will melt glaciers on land and flood the North Atlantic with fresh water, diluting the salty water and slowing down the natural sinking process that allegedly powers the mighty ocean circulation. So, naturally, scientists are interested in measuring the saltiness of the North Atlantic. And back in 2005 they discovered, to their dismay, that the waters were getting less salty. The culprit? According to the study in Science magazine, glacial melting, increased precipitation and continental runoff, which all the climate models say is the result of global warming. But two years later a different group of scientists took another look at the data and you’ll never guess what they found.

Yes, in 2007 they determined that the waters of the North Atlantic have been getting more salty, or less fresh. This time they looked carefully at different depths and different parts of the ocean and found that while fresh water was coming in, there were also some sources of very salty water from surrounding ocean channels that caused an overall increase in salinity. And what caused the increase? Why, global warming of course. The authors found that the freshness of the ocean and its heat content were negatively correlated. Something to do with evaporation and precipitation they surmised. Climate-change-baddy. So as the oceans warmed, they got more salty.

Which, among other things should lay to rest the concern about the AMOC shutting down. Except that in climate science you can always #HaveItBothWays so nothing is ever that straightforward.