Melting Arctic Doesn't Mean the Ocean's Gulf Stream Will Halt

It turns out that a melting Arctic is not the reason why Nordic Seas are becoming less saline. Scientists have found that the source of fresher water is actually linked to the Gulf Stream, which is ferrying water from the Atlantic to the Arctic.

The Nordic Seas have become fresher and fresher since 1950. In the past, the researchers believed this was largely due to increased river runoff and net ice melting in the Arctic. This less saline Arctic has been a large cause for concern, especially when it comes to the global oceanic currents that help regulate weather on our planet.

"It has been a concern that a layer of Arctic freshwater could impede the Gulf Stream's Arctic branch," said Tor Eldevik, one of the researchers, in a news release. "Going back in time--into and through ice ages--such a freshwater lid has been understood to reduce ocean circulation and thus the Gulf Stream's poleward heat transport."

In order to learn a bit more about these fresher waters and what might be behind them, the scientists analyzed available observations back to 1950. In the end, they found that the changing salt content in the Nordic Seas can be explained by the variable salinity of the Gulf Stream's Arctic branch entering the seas from the south. The researchers then confirmed this finding with a numerical ocean model. Essentially, net precipitation over the North Atlantic Ocean is causing an increase in freshwater there. This freshening is then spread with the help of the Gulf Stream system and eventually spread further northward.

"Our study documents how large-scale changes in our marine climate propagate with the extension of the Gulf Stream into the Nordic Seas," said Eldevik. "This suggests that the marine climate could be predictable on the time scale that a climate signal is travelling north."

The findings are published in the journal Nature Geoscience.