Thread by @GlobalEcoGuy

Oh my god. The @Guardian needs to issue a correction here, as quickly as possible, for this sloppy reporting.

theguardian.com/environment/20…

Here are some of the many problems with the piece.

First and foremost, they are confusing the Gulf Stream with the AMOC -- or the "Atlantic Meridional Overturning Circulation".

They are *not* the same thing. Not at all. It's like comparing a super highway with a side street.

The Gulf Stream is a HUGE current on the surface of the North Atlantic Ocean, carrying about ~150 Sv of water. (1 Sv equals 1 million cubic meters of water per second.)

It comes from the tropics along the North American coast, and then heads from Cape Cod towards Ireland.

This current is caused by wind patterns in the tropics (trade winds) and the mid-latitudes (westerlies), plus the Earth's rotation.

As long as the wind blows and the Earth rotates, the larger Gulf Stream ocean current is going to continue. There is zero chance it will collapse.

Every major ocean basin has a current like this. They are called "Western Boundary Currents". They are crucial parts of our climate system.

The Pacific has one too, off the coast of Japan.

A small branch of the Gulf Stream (the "North Atlantic Drift") heads towards the Norwegian and Greenland Seas, which is the small piece that connects the Gulf Stream to the AMOC system.

That's it. The Gulf Stream and the AMOC are only connected by the North Atlantic Drift.

Think of a super highway of warm water going in a big loop around the Atlantic. That's the Gulf Stream.

A small "side road" of water (about 10% of the Gulf Stream) heads north -- like an exit -- towards the far north, off the coast of Norway & Greenland.

That the NA Drift.

Then this side road the water gets cold & salty, forming pools of water that sink.

That's the third road. And it heads downward, way below the surface, and slowly spreads (as a larger, diffuse water flow) towards the South Atlantic.

A bad analogy, maybe, but you can consider:

- The Gulf Stream is a superhighway of warm water circulating around the North Atlantic

- A small road (the North Atlantic Drift) branches off, heading north

- And this goes to a third, smaller road, where the AMOC begins

So the AMOC begins with the sinking of cold, salty water in the Norwegian and Greenland Seas, where it slowly spreads back south, well below the surface.

That slow, deep, cold current is only about ~1/10 as large (10-20 Sv) as the Gulf Stream.

There is evidence that this deeper, smaller, colder current has slowed down, and even collapsed, in the past.

The impacts of this would be profound in the Greenland and Norwegian Sea. It would probably introduce some cooling to a region that otherwise would be warming now.

The Pacific (and all major ocean basins) have a current similar to the Gulf Stream.

The North Atlantic also has this AMOC system, but the Pacific does not have a parallel to this.

If the AMOC collapses -- but there is no direct evidence of this -- it would be a serious issue for that region. But the larger Gulf Stream circulation would continue operating, largely as before.

Now will the AMOC (NOT the Gulf Stream) actually collapse?

Maybe. Maybe not.

Here is some great information about the AMOC, which gets to the best science out there:

https://twitter.com/EleanorFrajka/status/1683917521735368704?s=20

Bottom line, let's stop confusing two different ocean currents!

~90% of the Gulf Stream has nothing to do with the AMOC. And they are only connected by the North Atlantic Drift.

And the Gulf Stream itself WILL NOT "COLLAPSE".

This Guardian article also has several other problems, which I won't go into here.

But can we please remember that permafrost *thaws* and does not melt? And methane feedbacks are covered extensively in the IPCC.

Please @guardian, do better.

The Gulf Stream is going to continue as long as the wind blows and the Earth rotates.

You mean the much smaller circulation down below, called the AMOC, which is being actively analyzed and observed.

p.s. Of course the AMOC is a big deal for climate, especially in key parts of the North Atlantic.

But it's simply not responsible for transporting nearly as much water, or (more importantly) heat, in the Earth System as the Gulf Stream -- which is not in danger of collapsing.

The two work very differently, and have very different roles in the Earth System.

With such important issues, it's important to get the basic facts right -- and at least *name the currents* correctly!

This is a nice summary from @rahmstorf on this recent discussion about AMOC.

Lots to digest here. But a first step is to make sure we don't confuse two fundamentally different currents!

realclimate.org/index.php/arch…

@rahmstorf Here’s a better media article… although it still incorrectly says the Gulf Stream is “part of” the AMOC, which is very weird. Two different things.

cnn.com/2023/07/25/wor…

@guardian Also, the hyperbolic claims of this impact “rains” around the world and the Amazon, etc., are wild speculation. There is no evidence for any of that. Maybe some model simulations somewhere, but there’s no way to test it.

@FuturesWise @guardian The article was written to grab attention and scare people. Not to be a balanced, insightful piece that informed them.

Also: read the original article. It’s a little dense if you don’t know the methods. But we’ll documented approach.

nature.com/articles/s4146…

For most of Europe, the Gulf Stream matters far more than the AMOC.