This is a recurring theme at the BBC, despite what they admit is a lack of evidence to support it, or in their words ‘huge uncertainties’. Typical alarmist ‘what if’ speculation in other words, ignoring recent findings. We refer them to the Woods Hole Oceanographic Institution study cited in our recent post: Critical ocean current has not declined in the last 60 years, AMOC study finds. Despite that the BBC says ‘Amoc appears to be getting weaker’. It goes on to talk about tipping points, but again we refer them to recent work: Scientists question use of ‘tipping point’ metaphor in climate change discussions.
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Of all the possible climate futures, there’s a scenario where the United Kingdom and north-west Europe buck the trend of global warming and instead face plunging temperatures and freezing winters, says the BBC.
It’s not the most likely outcome, but a number of scientists fear that the chance of it happening is growing, and that the consequences would be so great that it deserves proper consideration.
They are concerned that the ocean currents that bring warm water from the tropics to the North Atlantic could weaken – or even collapse – in response to climate change. [Talkshop comment – climate change IS a response].
Huge uncertainties remain about when – or even whether – a collapse could happen. So, how likely is it, and what would it mean?
. . .
But Amoc appears to be getting weaker.
We don’t know for sure, because direct and continuous measurements of Amoc strength have only been taken since 2004. That’s not long enough to be able to identify a definite change.
But indirect evidence suggests it could have already slowed by around 15% over the last couple of centuries, although not all scientists agree.
One indication is the sediments on the ocean floor. Larger grains indicate a stronger current. By measuring the size of the grains and calculating their age, scientists can estimate how much Amoc has slowed over time.
Another piece of evidence is the so-called ‘cold blob’ or ‘warming hole’ in the north Atlantic. This describes a region which appears to have cooled in recent decades, unlike the vast majority of the world.
A slowdown in Amoc – meaning less warmer water would be transported to this region – is seen as a possible culprit.
This is “a very clear signature and footprint of a classic Amoc slowdown” says Matthew England, professor of oceanography at the University of New South Wales.
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Where might the tipping point be?
No one really knows how close it may be.
In 2021, the IPCC said it had “medium confidence” that Amoc would not collapse abruptly this century, although it expected it to weaken.
But some more recent studies have pointed to a growing possibility of Amoc passing a tipping point in the coming decades, beyond which full collapse would be inevitable.
Each study comes with various caveats and uncertainties, and different climate models can give different results for a system as complex as Amoc.
“We don’t believe the idea of an Amoc collapse this century has substantially changed because of these new results,” cautions Dr Laura Jackson, oceanographer at the Met Office.
Full article here.
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Image credit: researchgate.net
via Tallbloke’s Talkshop
February 2, 2025 at 05:15AM
Iowa Climate Science Education 