From NOT A LOT OF PEOPLE KNOW THAT
By Paul Homewood
Yes, it’s that old bogeyman again!
From the Mail:
The network of ocean currents which keep the Earth’s climate stable could be about to collapse, scientists have warned.
In an open letter, 44 of the world’s leading climate scientists say that key Atlantic Ocean currents – including the Gulf Stream – are on the brink of failure.
The scientists caution that the collapse of the Atlantic Meridional Overturning Circulation (AMOC) could lead to ‘devastating and irreversible impacts’ which will affect ‘the entire world for centuries to come’.
The resulting climate fallout could plunge the UK into a ‘new Ice Age’, with winter temperatures plummetting up to 15°C (27°F) below the current average.
While the collapse of the Gulf Stream would be disastrous for Britain, that vital current is just one small part of AMOC’s massive global system.
This giant ocean conveyor belt is critical for moving heat around the planet, but research suggests that it has been slowing down and could soon reach a tipping point.
Without urgent action, the scientists warn that AMOC could fail completely within the next few decades.
As warm water travels northwards from the tropics, it hits the sea ice around Greenland and the Nordic countries, cooling and becoming much saltier.
As the water cools it becomes denser, sinking rapidly towards the bottom of the ocean where it flows back southwards before once again warming and rising to the surface.
This process of ‘deep water formation’ is the engine for a vast global conveyor belt which pumps heat and water all around the Atlantic Ocean.
However, studies suggest that AMOC’s deep water engine has started to slow and is now showing worrying signs of breaking down altogether.
As global temperatures rise, melting ice pours fresh water back into oceans, diluting the denser salty water and preventing it from sinking.
If this process were to break down entirely, it would have catastrophic knock-on effects including the weakening of the Gulf Stream and the disruption of global weather patterns.
https://www.dailymail.co.uk/sciencetech/article-13991003/Gulf-Stream-COLLAPSE-soon-scientists.html#newcomment
Its “The Day After Tomorrow” all over again!
As with a lot of climate scams, this one is based on just a few years data, from which the “scientists” conclude that they have identified cataclysmic changes that have not happened for millennia.
The Met Office give a more balanced summary:
https://www.metoffice.gov.uk/weather/learn-about/weather/oceans/amoc
Note this particular sentence:
Oceanographers have been measuring the AMOC continuously since 2004. The measurements have shown that the AMOC varies from year to year, and it is likely that these variations have an impact on the weather in the UK. However it is too early to say for sure whether there are any long term trends. Before 2004 the AMOC was only measured a few times,
So we only have data since 2004, and the year to year variations are large. To pretend that such a short series is in any way significant is not only unscientific but fraudulent.
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
It would appear that there is little trend since around 2008.
The idea that the AMOC never changed before 2004 is absurd anyway.
Bob Dickson & Svein Østerhus laid out in their study, “One hundred years in the Norwegian Sea”, the major climatic changes in the Norwegian Sea and the rest of the Arctic:
All were associated with changes in Atlantic currents and the AMOC. The Warming in the North, for instance, occurred because of the influx of warm Atlantic seawater, in exactly the same way as with recent Arctic warming. As the Met Office explain, warm water evaporates leaving saltier water, which sinks because it is more dense. Saltier water of course freezes at lower temperatures, so Arctic sea ice tends to contract. (Note when it freezes, the salt tends to leech out, so either way the sea becomes saltier).
The Great Salinity Anomaly which followed the Warming was the result of that influx of warmer water retreating, in part because of northerly airflow :
http://www.tandfonline.com/doi/pdf/10.1080/00291950701409256
.
These weather patterns are part and parcel of the Arctic Oscillation, another perfectly natural cycle. The anomalously higher pressure over Greenland marks the time of the negative AO:
From NSIDC:
https://nsidc.org/cryosphere/icelights/2012/02/arctic-oscillation-winter-storms-and-sea-ice
As fresh, polar water replaced warmer Atlantic water, salinity levels fell – hence the name given to the event. Just as Arctic sea ice had retreated during the Warming, it expanded rapidly during this period. The GSA was not just a phenomenon in the Norwegian Sea, because the polar gyre carried this fresh water around the whole of the Arctic Ocean.
Another factor identified by Dickson and Osterhus in the freshening of the Arctic Ocean is increasing discharge from Eurasian rivers into the basin. A warming climate means a wetter climate in those regions. And more river discharge leads to more sea ice and a colder Arctic.
In other words, these processes tend to be self correcting. Milder weather leads eventually to more sea ice and a colder climate, until eventually the AO flips back to positive again.
I’ll leave the final comment to Dickson & Osterhus:
All these changes were the result of natural processes. There is no evidence that these will change in future.
Related
