Is The Gulf Stream Really About To Collapse & Cause Climate Mayhem?
Is The Gulf Stream Really About To Collapse & Cause Climate Mayhem?
It's not so straightforward.
2023 is the year that climate change really started to bite. The insane temperatures over the past few months have woken many up to the sheer scale and danger of our climate crimes. But a recent study put the cat among the pigeons, as it predicted a catastrophic Day After Tomorrow — esque climate tipping point could be reached as soon as 2025, turbocharging climate change and unleashing hell upon the Americas and Europe. But is this doomsday prediction to be believed?
This all starts with the Atlantic Meridional Overturning Circulation (AMOC), also known as the Gulf Stream. This is a system of interlinked cool deepwater currents and warm surface currents driven by winds and sea ice. You see, as sea ice forms, the water around the ice sheets gets saltier and, therefore, denser, as ice can’t contain salt. This cold, dense water sinks, drawing warmer surface waters in from further South. Meanwhile, trade winds in the tropics blow the warm surface waters northwards, which pulls cold water up from the depths of the tropics. As these two systems are linked, water goes around and around, travelling between the tropics and the Arctic.
The AMOC is actually one of the most critical climate systems in the Atlantic region. The cold upwellings it creates in the tropics bring vital nutrients from the ocean depths, enabling algae to grow, creating a carbon sink. The warm water it brings to the Arctic is still nutrient-rich, and its warmth keeps the Arctic Sea ecosystem thriving, even in the highest latitudes. But this great conveyor belt also dramatically affects the climate of both Europe and America. It keeps north Europe considerably warmer through winter than their American cousins on the same latitudes, around 20 degrees Celsius warmer. This extra wintertime heat stabilises winter weather in these regions and is why most of Northern Europe is so habitable. It also stabilises rainfall and winter weather in much of the US by again providing a little heat through winter.
But, many scientists think that the AMOC is slowly grinding to a halt. You see, the main driving force of the AMOC is the winter growth of the ice sheets, and climate change is causing the Arctic to warm 2.5 times faster than the rest of the world. This has devastated the ice sheets, and the Arctic has lost around 72% of its sea ice (measured from summer minimum) since 1980!
So what would happen if the AMOC failed and stopped?
Firstly, it would accelerate climate change. The oceans absorb around a third of our carbon emissions; this is through both biological and chemical pathways. The biological pathway starts with algae, which absorbs sunlight and atmospheric carbon dioxide (which has dissolved into the ocean water) to produce carbon-rich organic compounds to feed themselves and build their bodies out of. When they die or get eaten, this carbon slowly sediments its way down and settles on the sea floor. The chemical pathway starts with carbon dioxide dissolving into ocean water, which turns it into carbonic acid and carbonates. These then interact with minerals on the ocean floor and create solid carbon-rich minerals, locking the carbon away for millennia.
Both of these processes are greatly helped by the circulation provided by the AMOC, as it physically pushes the algae and carbon dioxide-rich top water down into the depths, where the carbon can settle before it can find its way back into the atmosphere. So if the AMOC stopped, the net impact of each kg of carbon emissions we emit would be more significant, and climate change would speed up.
Secondly, this would stop nutrients from being replenished within the Atlantic, which would significantly reduce biomass and biodiversity. This will be devastating for marine ecosystems and the millions of people who depend on the Atlantic fish stocks for sustenance.
It would also wreak havoc with weather patterns across the US and Europe. Rain patterns will drastically change, and seriously extreme winter weather will hit much of Europe and America with far more ferocity and frequency than it does today; hurricanes could become more powerful and more frequent, and heat builds up in the Caribbean seas. This will not only cause billions of dollars of damage annually and directly threaten millions of lives, but it will also significantly reduce the food supply of many developed Western countries as their crops can fail year after year. This reduced food supply has the potential to threaten our economies and cause recessions at a level we have never seen before.
So when a recent study found that the AMOC could collapse as soon as 2025, the mainstream media panicked (as they rightly should), worried about what horrors lie just over the horizon. But climate scientists were mostly sceptical, and some were even annoyed at this media frenzy. Why?
Well, this report actually stated that the AMOC collapse could happen any time between 2025 and 2095 with a 95% confidence interval. That is a massive range, and practically speaking, it means nothing. Climate scientists have known for a long time that global warming of a few degrees will likely weaken and eventually stop many ocean currents by the end of the century. So why the vast range? Well, it is complicated to measure the AMOC; you need a vast around of ocean-based and space-based sensors constantly monitoring one of the largest ecosystems in the world. As such, it has only been adequately measured and recorded since 2004. This makes it incredibly difficult to decipher between short-term events and long-term trends, as there simply isn’t enough data. From the little data we have, we know the AMOC flow rate naturally fluctuates over time with many different frequencies, which means the trends found in the study could just be a natural oscillation of the AMOC flow rate.
This means that, yes, there is a chance it could all grind it to a halt in a matter of years. But that is far from a solid prediction, as the data simply isn’t large enough to make such predictions accurately.
That’s why climate scientist Prof Penny Holliday, who specialises in ocean circulation, told the BBC, “We just don’t have the evidence to state that it has declined. We know that there is a possibility that Amoc could stop what it’s doing now at some point, but it’s really hard to have certainty about that.” Another climate scientist, Prof Jon Robson, also told the BBC that their scepticism does not mean that the study is not important or that the possibility of the AMOC shutting down should be dismissed. He went on to say, “We do still have to take the idea seriously that there could be abrupt changes in the North Atlantic climate system.”
In other words, this prediction should be taken with a pinch of salt. But we should ensure we are doing everything we can to prepare and mitigate this potential Earth-changing event from happening, as there is still a significant (as in the scientific meaning of significant) chance it can happen within our lifetimes.
If nothing else, the media frenzy around this study indicates that we aren’t doing enough to combat climate change. Firstly, it shows that significant climate tipping points might not be as far away as we once thought, but also that the general public is heavily invested in their future not being scuppered by climate change. So hopefully, this study, at the very least, can help drive the changes we need to make to save this beautiful planet.
Thanks for reading! Content like this doesn’t happen without your support. So, if you want to see more like this, don’t forget to Subscribe and follow us on Google News and Flipboard and follow me on Twitter (let’s pretend it isn’t X), or hit the share button below.
Sources: NCEI, NASA, Scientific America, PBS, CBS, Met Office, NPR, BBC, Nature, Nature, Phys.org