'Early Warning Signs' of Gulf Stream weakening.

A snowHead

Just as we are starting to recover from the Covid-19 pandemic there's news of possible climate related problems ahead for the UK. rolling eyes

Researchers have warned that the natural phenomenon known as the Atlantic Meridional Overturning Circulation (AMOC), which includes the Gulf Stream, may have reached a point of ‘almost complete loss of stability’. Shocked

The AMOC acts like a conveyor belt carrying warm surface water to the North Atlantic, including from the tip of Florida towards Europe, making it significantly warmer than it otherwise would be. It seems that the AMOC can exist in one of two states; the current 'strong' mode or a 'weak mode'. In such physical systems that can exist in one of two states (bistable) there comes a point when changes to the system mean it is no longer stable in its existing state and a small further change can result in reaching a tipping point where it rapidly transitions to the other stable state.

If the AMOC were to switch to its weak mode then it seems the Gulf Stream would not shut down totally, but it would move further South from the UK resulting in significantly colder UK temperatures (could be good for Scottish skiing! snowHead

) and severely reduced rainfall during the growing season causing a big hit to the UK’s agricultural productivity.

Here's a link to the research published in Nature.

A snowHead

My understanding of one potential possibility - Is for the Gulf Stream to flow in the way it does, requires a certain salination of the Ocean. If the melting of the ice caps is severe enough, it has the potential to dilute the salt levels sufficiently to stop the Gulf Stream conveyer belt. Without the warmth from the Gulf Stream, we would feel the true effect of our geographical position - potentially freezing the sea for a mile around our coast in Winter.

Well, the person's real but it's just a made up name, see?

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There was an interesting Radio 4 "Today" section on this.

One thing that became clear was that the Gulf Stream is NOT in danger of switching!
AMOC and Gulf Stream are not the same thing at all...not even a little bit.

The academic who wrote this report was absolutely p1ssed off at what he described a lazy reporting...

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It's because when most people hear Gulf Stream they image a long red arrow from somewhere in Caribbean all the way to Norway

That has never been the case.

Gulf Stream runs along the US coast, and then becomes North Atlantic Current, which crosses the Atlantic to the British Isles, which in turns becomes Norwegian Current.

North Atlantic Current is a part of AMOC, Gulf Stream isn't.

Still we may all end up commuting on skis Toofy Grin

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I knew this was for real when I watched “The Day After Tomorrow”

After all it is free

@Ricklovesthepowder, Laughing

I hate it when 'experts' offer conflicting accounts. Could someone please clarify whether the end of the world is nigh?

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What's the doom forecast for tomorrow, as I've laundry to put out.

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No point putting the laundry out then.

You know it makes sense.

Alastair Pink and Oleski, it is very confusing when the media gets hold of concept and tries to simplify.
The MetOffice has nice video:

http://youtube.com/v/eu7ZDi2wHqY&t=9s

It seems the AMOC is global, while the gulf stream is just that part setting off from north America towards Europe
(https://www.metoffice.gov.uk/weather/learn-about/weather/oceans/what-is-the-gulf-stream)

Otherwise you'll just go on seeing the one name:

On the plus side, if we’ve moved into climate change (as all media seem to have done) then pandemic must be over

Onto the next thing

Did I mention meteorite strikes?

A snowHead

Interesting that that AMOC system doesn't go past Central NA and LATAM. So must be some interplay with pacific systems and indeed a cape/antarctic system.

A snowHead

Germany worst floods in sixty years.......

Greece worst forest fires in thirty years.....

That said you can't ignore the planet is warming up, by just seeing how French Alpine glaciers have shrunk, but does that affect forest fires and the like?

Well, the person's real but it's just a made up name, see?

Much of the US West is now a tinder basket every summer as well. I find it hard to separate the anectodal (one year's exceptional flooding) from the statistically significant but it seems to me entirely plausible that we're at a tipping point. How much is due purely to climate change and how much to man's physical expansion over the earth e.g. building on floodplains, into forests and mountains, diverting riveers, over concreting in urban areas etc ?

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There is a vast area in the mid pacific, known as the Sub tropical Gyre, where there is very little circulation. Lost of rubbish collects here. The water is very low in oxygen, and nutrients, and is comparatively, void of sea life.

The main cause is the sheer size and depth of the Ocean, and the lack of underwater mountain ranges, that cause upswelling in other parts of the world. These upswellings bring the cooler water filled with nutrients, to the surface, which in turn supports the food chain.

Classic example of this is the Galapogos.

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@Dave of the Marmottes, There is a clue in the name "flood plane", but it seems to have evaded the logic of Planners and developers throughout the world. rolling eyes

Logic would say to build on stilts to raise the ground floor up, and keep electrics near the ceiling instead of the floor. If the ground floor was garage and storage, with 2 floors above, any flood damage would be minimised.

Local authorities could insist that any developements are adapted to suit the local threat levels, but never seem to bother. The proposed changes to planning won't help, as local input will be reduced.

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Large areas of tarmac/concrete/paving on housing don't help. Water just runs off and gets moved as a problem in a different area.

A simple gully trap on the boundary and soak away as a standard requirement would vastly help reduce flooding in some areas on all but the most severe cases.

Maybe a change to the water rate system?
Reduced costs to those who allow rainwater to soak into the ground, and more punitive charges for those who don't?

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@jellylegs,

After all it is free

@foxtrotzulu, Blimey that rekindled memories of drunken uni parties!

@Haggis_Trap, has a point about changes over the last decade or so, 2018 as a whole being a good example, hard winter, hot dry summer for Highland Scotland.

There’s evidence that during the part of the Younger Dryas known as the Loch Lomond Stadial that climate was substantially more continental in Scotland with markedly more defined seasonality. A lecturer I had at uni has done a lot of research on reconstructing this period, 25 years ago the notion of abrupt climate change by tipping points flicking AMOC on / off was controversial but evidence was growing that was just what caused the Loch Lomond Stadial.

The cause was vast influxes of fresh water to the North Atlantic as ice sheets continued to retreat from the glacial maximum, disrupting the deep water formation that drives AMOC.

However there’s a history of cyclical winter conditions in Scotland partly correlated to the Atlantic Multi-decadal oscillation which may have been exacerbated by another human factor that may explain the period of frequently bad & particularly poor Scottish Ski seasons in the late 80s and 90s, declining in influence in the 2000s - Ozone depletion.

The IPCC says “extremely likely that human-caused stratospheric ozone depletion was the main driver of cooling of the lower stratosphere between 1979 and the mid-1990s” - this will have driven a stronger polar vortex and increased zonality in the weather patterns affecting Scotland.

All said and done if skiing in Scotland was to stop because of climate change in our lifetimes, skiing would be the least of our worries. Not least that as climate models continue to improve there is growing evidence that some of the least warming will occur in Highland Scotland in winter.

Many models don’t handle tipping points in thermocline circulation well, but that Highland Scotland in winter looks to have amongst the least warming on earth (particularly in worst case scenarios) could point to something spectacular being far to close for comfort with regards to AMOC.

Scottish Skiing might boom, but **** knows where the pies will come from! Skullie

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A mate who's a civil engineer has spent the latter part of his career doing flood assesments for various building projects, from housing estates to major infrastructure projects. All based on 100year storm threat. According to him what was considered a 100yr storm a few years ago is now a 10yr storm

@brianatab,

You know it makes sense.

You all lack any sense of perspective. These cycles are hundreds of thousands of years in length. Given that the other cycles that interact with them are millions of years in length none of this is out of the ordinary.

Otherwise you'll just go on seeing the one name:

Perhaps a bit selfish but if the Gulf Stream is weakening and it’s immediate affects are represented by the last 8 months of weather (they probably aren’t) I’d take that!
The southerly jet has meant depressions 800 miles further south than normal putting the north and west in persistently drier and cooler weather this winter with very little of the flooding we have become used to. Summer has been really good up here. We still haven’t had much rain on the east side of the Pennines and the garden is dry. I carnt remember a year when we have been able to sit outside so often.
The slack jet has made a big difference this year. I’m sure it won’t last. This winter will probably be the wettest on record for the north etc

A snowHead

@foxtrotzulu, Glad to hear you get a rebate for letting it soak into the ground.
Problem is, that the reverse doesn't yet apply.

The surface water drainage really only applies to the rain that lands on your roof, and goes into the drains. If you have a large(ish) garden, then most of the rain falling on that area soaks into the ground. There is no charge for this, as it replenishes ground water levels.

Those who have large tarmac areas, pay the same as those with garden areas, however, proportionately more water from that property, which would otherwise drain into the ground, just runs off and ends up in the sewer system. In many cases, it just drains onto the roads, whose systems were not designed to take it, resulting in floods in areas that, traditionally, never had them.

Problems occur in sewer systems that were simply not built to take the current volumes, and it is people further down the system that experience the problems.

There is also an inevitable extra cost to the water Companies, as they are having to treat additional water that should be in the ground.

That's why I suggested either compulsory soakaways, or punitive charges for those who don't install them, with the additional revenue set aside for alleviation work.

Putting a soak away channel at the end of your new tarmac or paved drive would add very little to the overall cost, but could help save millions in environmental or property damage.

Help!!

'Early Warning Signs' of Gulf Stream weakening.

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