Are Ocean Currents Collapsing? Separating Science from Bad Reporting

The other day I was scrolling through science news when I saw a paper published in Nature suggesting that the Atlantic meridional overturning circulation (or AMOC, which is a system of ocean currents in the Atlantic ocean that bring warmer water north and cooler water south) is on the bring of collapse, which may happen as soon as 2025. That is quite alarming news and I was understandably concerned.

Imagine my surprise when just MINUTES later I happened across an article in the Guardian saying that the GULF STREAM is ALSO on the brink of collapse, which may happen as soon as 2025! Holy shit that year is going to SUCK.

Okay, no, the Guardian just managed to get this hilariously wrong, as did a number of other news outlets even though this is pretty basic information: the Gulf Stream is a very large system of currents driven by wind and the rotation of the planet. It will not stop unless those things stop. Yes, if Earth stops spinning the Gulf Stream is in real trouble but also we will probably have bigger issues to worry about.

Jonathan Foley of Project Drawdown explains the difference between the two systems like this: if the Gulf Stream is a superhighway, then the Atlantic drift is an exit off of that superhighway, which leads to a small road that is AMOC. AMOC is much slower and much deeper than the Gulf Stream. I assume news outlets ran with Gulf Stream anyway because everyone has heard of that and no one has heard of AMOC, unless you happen to be one of the many scientists studying it and particularly its relationship with climate change.

Researchers have been directly observing AMOC since 2004 when they deployed a series of instruments to measure conditions on the sea floor from Morocco to Florida as part of the RAPID program. Scientists combine those direct observations with longer term indirect observations to try to figure out what AMOC has been up to in the past and what it might get up to in the future. This new study is based on those indirect measures–namely, sea surface temperatures, which is data we have going back to the mid 19th century. These measures are by definition overly simplistic, but they’re important because researchers need every scrap of data to put this puzzle together and figure out what’s most likely to happen.

That indirect data has led to a lot of past published research, as Stefan Rahmstorf describes on his site RealClimate.org. The preponderance of data suggests that the AMOC has been weakening over the past century and that it is caused by human activities. It also suggests that it’s always been super unstable, and that that instability is connected to some pretty severe climate events like, um, the last ice age? Which is why it really is a huge deal for humans if it suddenly comes to a halt! I barely survived this Northern California winter where it was 49F every day, I can’t handle an Ice Age.

So, should this new study make you worry? I mean, no? Not any more than every other study on climate change should make you worry. At some point you should reach peak “worried” and then just ride that feeling and use it to agitate for change. But the AMOC probably will NOT collapse in 2025. This study actually puts it in a window from 2025 to 2095, with a “critical” mean year of 2057.

But again, this is not based on direct measurements, because we only have those going back to 2004. As Dr Eleanor Frajka-Williams pointed out, the recent IPCC report found “medium confidence” that the AMOC will NOT collapse before 2100, but many climatologists, including Rahmstorf, think that’s too conservative. And of course, that’s how science works: experts agree on a particular consensus (the AMOC is weakening because of human activity and if it collapses the results will be disastrous) and disagree on the details while they collect more data (when will it collapse, and what will be the knock-on effects of such a collapse).

All of this beautifully illustrates something I discussed last month, when the mainstream media falsely blamed scientists for causing sea levels to rise because of a good study that actually just found better ways for scientists to communicate complicated ideas. They found that it’s very, very difficult yet very, very important for scientists and science communicators to properly discuss “ambiguous” findings. That study used the example of sea levels rising, pointing out that while the rapid disintegration of the West Antarctic Ice Sheet was “unlikely in the next century,” it’s one of many unlikely events that, were any one of them to come to pass, would have a devastating effect on humankind and so it’s probably worth avoiding. 

Now we have another great example: current data suggests it’s “unlikely” that AMOC will collapse in 2025, or maybe even before 2050, but if we don’t change what we’re doing then the chance that it will happen will continue to grow, and it is VITALLY important that we not let it happen.

I think that the authors of this Nature paper effectively communicated their findings, and I think the scientists who I’ve read on the topiccc, like Foley, Rahmstorf and Frajka-Williams, have done a great job communicating those findings to the general public. It’s a real shame, then, that mainstream science news reporters can’t even be bothered to get the name of the affected currents right, let alone put these findings into perspective. As bad as it is to downplay the climate catastrophe, it’s nearly as bad to stoke so much panic that people feel helpless to stop it. We CAN stop it. We just need our billionaires to start caring.