Running AMOC

AMOC? Oh please, 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 north 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 the Arctic ice to melt much 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 warmer and less dense, but the other, even more important, reason is that the meltwater is fresh. Fresh water is less dense than salty water, so it sinks less powerfully.

In other words, the driving force of Amoc, the sinking of arctic water and its slippage southwards, is weakening. The Gulf Stream is thus 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 it 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. They would devastate climate around the planet, in fact, but for now let’s just think about the effect on us, here in the UK. The average temperature in the UK might be 10 degrees or more lower than we presently enjoy – 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 interspersed with torrential rains and widespread flooding. This could happen anytime between 2025 and 2095 according to recent research.

Neither is very far away!

Life as we know it would change drastically and fast. It would, frankly, disappear. 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?

For further information, see:

https://en.wikipedia.org/wiki/Atlantic_meridional_overturning_circulation

So back we come to the old arguments: All of this is caused by climate change, by global warming, which is caused by burning or venting 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?

This question of ‘affordability’ has been comprehensively answered. Science and economics agree that we’ve got to pivot away from a fossil-fuel-based economy to one based on sustainable energies, as soon as possible. We know it can be done relatively easily (it disrupts only a few sectors of our economy). 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 is an enormous economic opportunity and would deliver the sunlit uplands for future generations that fossil fuels once did for mine. (Eminent economists, including Mark Carney, tell us this all the time. Chris Skidmore and Alok Sharma do too.)

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? The fundamental answers must run through politics. Climate mitigation is quite an organisational nettle, but governments just have to grasp it. They must do this single-mindedly and vigorously, and they need to begin right now now. Our job is to urge this imperative fact upon our MPs, as forcefully and frequently as we can. Our job is also to urge our MPs to recognise that science is almost always true and that a fact is a fact. That an honest understanding, and acceptance of reality is, or absolutely should be, bedrock to their work. Denial, or the short-term convenience of delay’, are existentially dangerous.

Ignoring science is disreputable and unacceptable. It is professional negligence writ large.

Our MPs, all of them, must be made to see that if they don’t want Amoc to fail, bringing our weather down with it, then they need to deliver genuine climate action up in Westminster. They must read and grasp the science and make the case for change.

So: write to your MP! Message, email or, best of all, speak to them.

Talk to everyone you know and get them to do the same, with the same urgency.

One day our MPs will get the message. With luck, it will be in time to rescue Amoc.

We have skin in this game, so it’s worth a go, isn’t it?