Stop ‘global warming’ to prevent cold! BBC: ‘Could the UK actually get colder with global warming?’ – ‘Temperatures in n. Europe could fall by a couple of degrees a decade’ & ‘become horribly, horribly cold … like living in northern Norway’

 

https://www.bbc.com/news/articles/cn938ze4yyeo

Could the UK actually get colder with global warming?

By Simon King and Mark Poynting – BBC Weather and Climate teams

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.

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.

Huge uncertainties remain about when – or even whether – a collapse could happen. So, how likely is it, and what would it mean?

The system of Atlantic currents, called the Atlantic Meridional Overturning Circulation (Amoc), is a key reason why the UK is warmer than Moscow, despite being a similar distance from the Equator.

Forming a vital part of our climate system, this conveyor belt distributes energy around the planet, bringing warm, salty water from the tropical Atlantic to cooler regions south of Greenland and Iceland, and also the Nordic Seas.

The warmth from the ocean is transferred to the air above it, helping keep temperatures milder than they otherwise would be.

As this salty water cools, it becomes denser, and sinks, before flowing back towards the southern hemisphere as a deep ocean current. This water eventually gets pulled back up to the surface, and the circulation continues.

Annotated map of the North Atlantic showing a simplified representation of how Amoc works. Warm, salty water flows northwards from the tropics, via the Gulf of Mexico, as a surface current, shown in red. It cools and sinks just south of Iceland, and flows southwards as a deep current, shown in blue.

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.

Map showing global average air temperatures over the decade 2014-2023, versus the 1961-1990 average. Almost all of the world has warmed considerably, particularly the Arctic, shown by oranges and reds. But there is a region just south of Greenland and Iceland in the North Atlantic Ocean that has not warmed, shown as a white or very light blue. This is known as the 'warming hole'.

What would happen if Amoc collapsed?

Even the most likely scenario – where Amoc continues to weaken this century – could have serious effects.

“If the Amoc gradually weakens over the next century, you’re going to get global warming but less warming over Europe,” says Dr Jackson.

That would still mean the UK getting hotter summers with climate change, but a weaker Amoc could also fuel more winter storms as regional temperature patterns change.

A full-scale collapse, meanwhile, would be “like a war situation […] something almost unimaginable,” says Prof Lenton.

While it could take a century or more for impacts to play out, temperatures in northern Europe could fall by a couple of degrees a decade.

Map showing possible effects of an Amoc collapse on European temperatures, excluding other effects of climate change. The UK and north-west Europe are shaded in the darkest blues, showing greatest cooling. Below the map is a graph showing the possible yearly air temperature change across European cities after an Amoc tipping point is crossed. Within about 50 years, Madrid and Vienna cool by 2-4C, London cools by about 7C, and Reykjavik and Bergen cool by 12-14C.

In the UK, it could “become horribly, horribly cold … like living in northern Norway,” Prof Thornalley warns.

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