Climate change may shut down a current that keeps the North Atlantic warm

By Rachel Becker

Both Europe and North America are warmed in the winter by currents circulating in the Atlantic — but climate change threatens this source of warmth. If the Earth warms too much, it’s possible that this current could collapse entirely, new research says. That would mean frigid winters for countries along the North Atlantic, expansion of the sea ice in the Greenland, Iceland, and Norwegian seas, and a shift in rainfall across the world.

The current is called the Atlantic Meridional Overturning Circulation (AMOC) and it’s like a conveyer belt that brings warm water from the tropics to the the cooler reaches of the North Atlantic. There, the water loses its heat to the atmosphere. Because water gets denser as it gets colder, it sinks. This lower band of cool water circulates back to the tropics where it warms and repeats the process all over again. If you’ve ever watched soup boil up, spread, and then sink, it works kind of like that.

“It is a major player in the climate system, important for Europe and North America. So it’s a big deal,” says Tom Delworth, a scientist with National Oceanic and Atmospheric Administration who was not involved in this recent study. The AMOC is the same current that collapsed and triggered an icy apocalypse in the 2004 movie The Day After Tomorrow (featuring Verge favorite Jake Gyllenhaal). “It wasn’t quite accurate in the science, but that’s okay, it was entertaining,” Delworth says.


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3 COMMENTS

  1. @OP – The current is called the Atlantic Meridional Overturning Circulation (AMOC) and it’s like a conveyer belt that brings warm water from the tropics to the the cooler reaches of the North Atlantic. There, the water loses its heat to the atmosphere. Because water gets denser as it gets colder, it sinks. This lower band of cool water circulates back to the tropics where it warms and repeats the process all over again.

    There is evidence that global warming is actually reducing the temperature off the East coast of Canada and USA, by increasing the number and tonnage of icebergs breaking off the Greenland glaciers and moving south on the Labrador Current.
    Perhaps the Titanic was one of the first victims of this!

    This cooling will end, when in the longer term future, Greenland eventually runs out of ice or perhaps sooner when it reduces!

    http://earthobservatory.nasa.gov/Features/Greenland/greenland_sidebar.php

    Of course the cold surface fresh melt-water also raises sea-levels, affects wind flow and local weather, and could alter ocean currents.

  2. Here’s the thing for me. I’ve grown excessively tired of the climate deniers. I mean like weary to my bones. This manifests in a few ways (one, I am aware of, but none too proud). First, I read these articles much much differently than in the past, and it’s probably a good thing. For example: this article is nebulous regarding how widespread this research is. Is it one possible outcome modeled on huge uncertainty? Is this a 1% possibility or a certainty? What percentage of models yield the exact opposite results?

    Here’s a piece of the OP:

    expansion of the sea ice in the Greenland,

    Here’s a piece of Alan4’s post:

    when in the longer term future, Greenland eventually runs out of ice

    Yes, I cherry picked. But, that is what the other side of this does and that is how easily they think they’ve made a case against the science.
    I think that the models should be consulted and not reported on so vehemently as to try to assert that they are truth. Then there’s this:

    The AMOC is the same current that collapsed and triggered an icy apocalypse in the 2004 movie The Day After Tomorrow (featuring Verge favorite Jake Gyllenhaal). “It wasn’t quite accurate in the science, but that’s okay, it was entertaining,” Delworth says.

    Which, it seems to me is exactly what should be being said about this research. It needs a disclaimer for the scientifically unexperienced and so that the deniers cannot key on the cherry picked items (like I did).

    The second thing that has evolved in my reading of these stories (and the one that I am ashamed of) is:
    Part of me is starting to think “GOOD”. I fucking hope the shit does hit the fan and these assholes lose everything that matters to them. Their shorefront properties, their yachts, their livings. Then, i realize what that means for the world ands I am ashamed. But damn, what cost, being right?

  3. crookedshoes #2
    Jan 17, 2017 at 2:12 pm

    @OP -Climate change may shut down a current that keeps the North Atlantic warm

    What this is saying, is that the surface circulation of the warm Gulf-Stream current from the Gulf of Mexico, which carries heat from the tropics across the Atlantic to warm Europe needs to be cooled as it reaches the arctic so that the water becomes more dense and sinks to return south along the ocean floor.
    It is this sinking of denser water which powers the circulation, so if the water becomes more dilute due to ice meltwater or does not cool sufficiently, due to a warmer atmosphere in northern latitudes, the circulation may slow or stop.

    It is this warm current which keeps the European coasts VERY MUCH warmer than the Labrador coast. (The Great Lakes and St. Laurence freeze in the winter. The seas around England at similar latitudes do not!)

    If this Gulf Stream circulation stops or reverses, Europe (locally) will become VERY MUCH colder as the Earth warms, (with even a possible temporary mini-ice-age) if the Gulf stream is replaced with a current from the Arctic Ocean.

    Climate science is complex, and to understand it people need to understand the basics.

    @OP – but climate change threatens this source of warmth.
    If the Earth warms too much, it’s possible that this current could collapse entirely, new research says. That would mean frigid winters for countries along the North Atlantic, expansion of the sea ice in the Greenland, Iceland, and Norwegian seas, and a shift in rainfall across the world.

    the 2004 movie The Day After Tomorrow

    The 2004 movie “The Day After Tomorrow”, is of course fiction for the US market, and probably has the ice on the wrong side of the Atlantic!

    https://www.nasa.gov/content/goddard/hidden-movements-of-greenland-ice-sheet-runoff-revealed

    University at Buffalo geophysicist Beata Csatho led an international team that produced the first comprehensive study of how the ice sheet is losing mass based on NASA satellite and airborne data at nearly 100,000 locations across Greenland. The study found that the ice sheet shed about 243 gigatons of ice per year from 2003-09, which agrees with other studies using different techniques.

    More recent studies show the losses continuing and accelerating.
    There are misleading local features which deniers latch on to.
    One is that due to a warmer climate and more moisture in the atmosphere, some local areas have increased snowfall, but the consequent local build-ups of frozen snow, are much nearer to 0°c than the much colder old melting ice, and hence more vulnerable to further thawing.

    As I pointed out in my previous comment, an increased break-up of the glaciers, at present leads to local chilling on the US east coast in the oceans where they melt as they drift south.

    An increased break-up could lead to a temporary increased chilling if more ice drifts south – right up until Greenland runs out of ice!

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