AMOCalypse

(or: Running AMOC? Losing the Gulf Stream?)

AMOC? Not another acronym!

Well, yes. But this one is a real biggie. It’s the acronym for a new name for what we used to call the Gulf Stream. This new name is the Atlantic Meridional Overturning Circulation.

Amoc is much easier, so let’s stick with that.

Amoc is the endless, very large-scale circulation of water from the frozen Arctic to the balmy Caribbean and back. It’s driven by the fact that cold, salty Arctic water is dense and heavy, so it sinks to the ocean floor up there. It’s got to go somewhere, so it slides south along the bottom of the Atlantic until it gets to the Caribbean (roughly speaking). Water has to move to make way for this huge amount continually arriving from the Arctic, of course, so warm Caribbean water slips along the surface of the Atlantic back towards the Arctic. It carries lovely Caribbean heat with it and leaves some of this with us. And this marvellous, life-giving Gulf Stream circulation has been going on for about 12,000 years. It never sleeps.

There’s a lot of water involved in Amoc, so there’s a lot of heat being transferred from the Caribbean toward the Arctic and to the lands alongside the Atlantic ocean, like the UK. We enjoy a temperate climate because of it – we’re much warmer than we should be, given how far north we are. This is because of Amoc bringing all that gorgeous Caribbean heat up to us. It’s Amoc that enables us to enjoy our benign weather, and the lives we live, with allotments, village cricket, fat cattle on green grass, daffodils in the parks, summer scorchers, conkers in golden autumns and soft rain to complain about on bank holidays.

There’s a ‘but’, though, and it’s a very scary one…

Global warming is causing Arctic ice to melt too fast, above and below the waterline. This is dangerous for two reasons: one is that the average water temperature is steadily rising so that arctic water is getting less dense, but the other, even more important, reason is that the meltwater is fresh. Fresh water is less dense than salty water, so sinks less powerfully.

In other words, the driving force of Amoc is weakening. The Gulf Stream is at risk of collapsing. The delivery of heat from the Caribbean to the UK is at risk of failing. Scientists worry about tipping points and losing Amoc is one of the most menacing ones.

What would this mean?

The science is only tentative as yet, although the signs of potential collapse seem to be disconcertingly real and the consequences of collapse would be absolutely devastating. The average temperature in the UK might be around 10 degrees lower than we presently enjoy, possibly even more – winters could regularly reach 20 or 30 below - and summers, if we had them at all, would be stormy and unpredictable affairs struggling to reach double figures but with episodes of searing heatwaves and intense drought. This could happen anytime between 2025 and 2095 according to the most recent research. Neither is very far away!

Life as we know it would change drastically and fast. Where would our food come from, once we couldn’t grow it reliably or perhaps at all? Could our houses withstand much deeper winters? Or more violent storms? Where would our money come from? Could society survive or would it fall apart under a tsunami of stresses?

So back we come to the old arguments: All of this is caused by climate change, which is caused by fossil fuels. People say (quite wrongly) that we “can’t afford” to mitigate climate change. But they don’t, or won’t, address the affordability of the alternative!

Can we “afford” the collapse of Amoc?

Of course not! And which is the most expensive option: Acting to stop climate change, or ‘maxing out’ on the fossil fuels and allowing the temperature to climb, climb and climb?

Science and economics agree that we’ve got to pivot away from a fossil-fuel-based economy to one based on sustainable energies, asap. We know it can be done relatively easily. We have the know-how (and are very good at inventing more). We know we can afford it. (We spent more on Covid than climate mitigation would cost.) We also know that a more sustainable economy would deliver sunlit uplands for future generations as fossil fuels once did for us. (Eminent economists, including Mark Carney, tell us this all the time.)

To continue burning (and venting) fossil fuels will condemn us to a variety of disasters of which the collapse of Amoc is only one. We can’t go on like this!

So: What can we do?

We think the answer must run through ‘politics’. Climate mitigation is quite a nettle, but governments just have to grasp it. They have to do this vigorously, and they have to do it now. Our job is to urge this fact upon our MP, as forcefully and frequently as we can.

Our MP, Robert Courts, must be made to see that if he doesn’t want Amoc to fail, bringing our weather down with it, then he needs to urge real climate action up in Westminster. So write to him! Message him. Email him. Talk to everyone you know and get them to do the same, with the same urgency. One day he’s bound to get the message and it’s just possible it will be in time to rescue Amoc.