Atlantic Ocean circulation is the weakest in at least 1,600 years

[Swift]

CBS News

No, we're not going to reenact the movie "Day After Tomorrow", but we are changing the climate.

An influential current system in the Atlantic Ocean, which plays a vital role in redistributing heat throughout our planet's climate system, is now moving more slowly than it has in at least 1,600 years. That's the conclusion of a new study published in the journal Nature Geoscience from some of the world's leading experts in this field.

Scientists believe that part of this slowing is directly related to our warming climate, as melting ice alters the balance in northern waters. Its impact may be seen in storms, heat waves and sea-level rise. And it bolsters concerns that if humans are not able to limit warming, the system could eventually reach a tipping point, throwing global climate patterns into disarray.

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As is the case with many sci-fi movies, the plot is based on a real concept but the impacts are taken to a dramatic extreme. Fortunately, an abrupt halting of the current is not expected anytime soon — if ever. Even if the current were to eventually stop — and that is heavily debated — the result would not be instant larger-than-life storms, but over years and decades the impacts would certainly be devastating for our planet.

Recent research has shown that the circulation has slowed down by at least 15% since 1950. Scientists in the new study say the weakening of the current is "unprecedented in the past millennium."

Nature Geoscience

Abstract:

The Atlantic Meridional Overturning Circulation (AMOC)— one of Earth’s major ocean circulation systems—redistributes heat on our planet and has a major impact on climate. Here, we compare a variety of published proxy records to reconstruct the evolution of the AMOC since about ad 400. A fairly consistent picture of the AMOC emerges: after a long and relatively stable period, there was an initial weakening starting in the nineteenth century, followed by a second, more rapid, decline in the mid-twentieth century, leading to the weakest state of the AMOC occurring in recent decades.

[profloater]

For us in the UK or Europe, this could be rapidly severe, changing the climate to that of NE Canada today. Of course the whole US East coast is affected too, but it might slow Arctic warming as a bonus. No one knows if the change might continue to be gradual or if there is a tipping point.