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Terrifying New Study Finds That Ocean Currents Will Soon Collapse
Brace yourselves for a globe-shaking marine ecological disaster.
Have you seen The Day After Tomorrow? This early naughties disaster movie’s whole plot revolved around climate change turning off global ocean currents and plunging the world into a sudden Ice Age. Many lambasted the film for exaggerating how soon these currents could collapse and how rapidly their knock-on effects can be felt, as we thought that such events wouldn’t happen for well over a century. But a recent study, which focused more on the Antarctic portion of these currents, found that global ocean currents could collapse in only 30 years! What’s more, while the knock-on effects of this are completely different to those seen in The Day After Tomorrow, they are arguably no less devastating. The question has to be asked, is there anything we can do to stop this?
Let’s start at the beginning. What are global ocean currents, and what powers them?
The global ocean current is a series of interlinked deep water and surface currents driven by winds and ocean saltiness. You see, in the water near Greenland and in the Weddell Sea off Antarctica, massive volumes of ocean water freeze into giant ice sheets. When seawater freezes, it leaves behind its salt, making the waters around these ice sheets saltier than normal seawater and, therefore, denser. This denser water sinks, drawing in new surface waters, and creates a current. Thanks to the deep topography of the sea bed off Greenland and the Weddell Sea, this denser saltier water is pushed out towards the tropics as deep sea currents, where they collect nutrients. Winds push surface water off the tropics towards the poles and, in turn, suck up these deep-sea currents to the surface, creating a looping global ocean current that snakes around the entire world.
You might think these currents are just a quirk of ocean dynamics, but they play a vital role in worldwide climate, are a crucial part of Earth’s carbon cycle and are an integral part of ocean ecosystems.
You see, these currents bring warm surface waters to the poles and cold waters to the tropics. This acts as a climate regulator, making weather patterns less extreme and sharing the Earth’s heat more thoroughly through its latitudes. This helps make vast amounts of Earth’s surface far more habitable.
The Ocean also absorbs carbon dioxide, turning it into carbonic acid. In fact, the ocean absorbs about 25% of our emissions, helping to delay human-driven climate change. The global ocean current takes the carbonic acid and buries it in the ocean’s depths, where it turns into carbonates and is safely buried away for millennia.
As the deep sea part of the currents chugs along the seafloor, they pick up nutrients such as iron, phosphate, nitrogen and calcium. These are vital for marine life and are surprisingly lacking in much of the world’s sun-lit seas, making the nutrients the limiting factor to how much life can exist in the oceans. So, where these deep-sea currents upwell, you will find massive thriving marine ecosystems.
So, how are these currents being stopped? Well, climate change. As the globe heats up, less and less polar ice is being formed, which decreases the rate of sinking water in the waters off Greenland and in the Weddell Sea. This acts in the same way as pinching a hose, and the rate of flow across the entire global ocean currents also slows down.
But, if either the Weddell Sea or Greenland down-flow mechanisms stop, it will collapse the entire global current system as the loop will be broken. If this happens, climate and ecological models predict far more extreme weather and a crash in marine biodiversity. Equatorial, near-equatorial countries and even some subtropical countries (like India) could become too hot for year-round human settlement, as unrestrained heatwaves run wild each summer. Many Northern-Hemisphere countries will experience winters so harsh that, again, year-round human settlement will be extremely challenging. Crucial currents like the Humboldt Current and Gulf Stream will stop and effectively starve the ocean of nutrients, leading to marine ecosystem collapse.
While these devastating knock-on effects aren’t the same as those in The Day After Tomorrow, they still have the potential to cause vast loss of human life and unrepairable damage to the environment and the biosphere.
Despite this, scientists have been quite confident that this isn’t a pressing issue. You see, all of their climate models suggested that we wouldn’t see global ocean currents grind to a halt for centuries!
But the studies that these models were based on were massively biased towards the Northern Hemisphere, as most studies into these currents are based on those in the northern stretch of the Atlantic Ocean.
However, a groundbreaking new study suggests that while the Northern Hemisphere Greenland down-flow will be stable for well over a century, the Southern Hemisphere Weddell Sea down-flow is far more sensitive to climate change.
The models used by this study predict that by 2050 the Weddell Sea down-flow rate will reduce by a massive 42%. This might be enough of a reduction to destabilise the current and break the loop. At the very least, it will massively reduce the global ocean current’s power. But it is set to get worse, as their models predict that this down-flow will shut off by the end of the century and fully collapse the global ocean current.
Just a reminder that even a small decrease in the power of the global ocean currents will lead to accelerated climate change (as less carbon dioxide is absorbed by the ocean), deadly extreme weather, and marine ecosystems potentially collapsing. So, this discovery is huge! It takes the already tiny amount of time we have to change our ways, and save the planet, and practically cuts it in half.
So, how do we overt this global disaster, save the oceans and keep our climate stable enough to be habitable? Well, we need to make sure we hit our climate goals and become carbon-neutral by 2050, and keep global warming to only 1.5 degrees Celsius, or 2 at a push. This way, there should be enough sea ice to power to keep the currents just about ticking over. This means we have less than 27 years to get our collective act together and reshape how our entire civilisation operates. And I’m not sure if we can do that…
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