not many people know
Paul Homewood
Yes, it's that old monster again!
From email:
Scientists warn that the network of ocean currents that keeps Earth's climate stable may be about to collapse.
Major Atlantic ocean currents, including the Gulf Stream, are on the verge of collapse, 44 of the world's leading climate scientists said in an open letter.
Scientists have warned that a collapse of the Atlantic Meridional Overturning Circulation (AMOC) could lead to “devastating and irreversible effects” that would affect “the entire world for centuries to come.”
The resulting climate impacts could push the UK into “New Ice Age”winter temperatures plummeted 15°C (27°F) below the current average.
While a collapse of the Gulf Stream would be catastrophic for the UK, this important current is only a small part of the AMOC's vast global system.
This giant ocean conveyor belt is critical for transporting heat around the Earth, but research suggests it has been slowing down and may soon reach a tipping point.
Scientists warn that without urgent action, the AMOC could fail completely within the next few decades.
As warm water flows north from the tropics, it hits sea ice around Greenland and Nordic countries, cooling and becoming saltier.
As the water cools, it becomes denser, sinks quickly to the ocean floor, then flows back south before warming again and rising to the surface.
This process of “deep water formation” is the engine of a vast global conveyor belt that transports heat and water around the Atlantic Ocean.
However, research shows that AMOC's deepwater engines have begun to slow down and are now showing worrying signs of complete damage.
As global temperatures rise, melting ice pours fresh water back into the ocean, diluting denser salt water and preventing it from sinking.
If this process breaks down completely, there will be catastrophic chain reactions, including A weakening of the Gulf Stream and disruption of global weather patterns.
https://www.dailymail.co.uk/sciencetech/article-13991003/Gulf-Stream-COLLAPSE-soon-scientists.html#newcomment
It's “The Day After Tomorrow” again!
Like many climate hoaxes, this one was based on just a few years of data, from which “scientists” concluded that they had detected catastrophic changes that had not occurred for thousands of years.
The Met Office gave a more balanced summary:
https://www.metoffice.gov.uk/weather/learn-about/weather/oceans/amoc
Please note this particular sentence:
Oceanographers have been continuously measuring the AMOC since 2004. However, it's too early to determine whether there are any long-term trends. Prior to 2004, AMOC had only been measured a few times;
So we only have data since 2004, and it changes a lot from year to year. Pretending that such a short series means anything is not only unscientific, but also deceptive.
This is what the series shows:
https://climexp.knmi.nl/getindices.cgi?WMO=NOCData/moc_mar_hc10_mon&STATION=AMOC_26N&TYPE=i&id=someone@somewhere&NPERYEAR=366
There seems to be no trend since around 2008.
Regardless, the idea that AMOC never changed before 2004 is ridiculous.
In their study “One Hundred Years in the Norwegian Sea”, Bob Dickson and Svein Østerhus describe the main climate changes in the Norwegian Sea and other areas of the Arctic:
All of this is related to changes in the Atlantic currents and AMOC. For example, northern warming occurs due to the influx of warm water from the Atlantic Ocean, in exactly the same way as recent warming in the Arctic. As the Met Office explains, when warm water evaporates, it leaves behind saltier water, which sinks because it's denser. Of course, salty water freezes at lower temperatures, so Arctic sea ice tends to shrink. (Note that when it freezes, salt tends to leach out, so the water will be saltier either way).
Large salinity anomalies that occur after warming are caused by the retreat of warm ocean waters, partly due to northerly air currents:
http://www.tandfonline.com/doi/pdf/10.1080/00291950701409256
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These weather patterns are an important part of the Arctic Oscillation, another perfect natural cycle. Abnormally high pressure over Greenland marks the time of negative AO:
From NSIDC:
https://nsidc.org/cryosphere/icelights/2012/02/arctic-oscillation-winter-storms-and-sea-ice
As fresh polar water replaced warm Atlantic water, salinity dropped—hence the event's name. Just as Arctic sea ice recedes during periods of warming, it expanded rapidly during this period. GSA is not just a phenomenon in the Norwegian Sea, as the polar gyre carries this fresh water throughout the Arctic Ocean.
Dixon and Osterhus found that another factor in the refreshing Arctic Ocean was the increased flow of Eurasian rivers into the basin. A warming climate means wetter climates in these areas. More river discharges will lead to more sea ice and a colder Arctic.
In other words, these processes tend to be self-correcting. Mild weather will eventually lead to more sea ice and colder climate, until eventually the AO returns to positive values again.
I leave my final comments to Dickson & Osterhus:
All these changes are the result of natural processes. There is no evidence that these will change in the future.
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