A claim that a “The Day After Tomorrow” style global warming driven ice age is imminent – but we’ve been looking at the wrong ocean.
New Research Sparks Concerns That Ocean Circulation Will Collapse
Scientists have long feared that warming could cause a breakdown of ocean circulation in the North Atlantic. But new research finds the real risk lies in Antarctica’s waters, where melting could disrupt currents in the next few decades, with profound impacts on global climate.
BY FRED PEARCE • APRIL 18, 2023
It is being hailed as a sea change in scientific understanding of the global ocean circulation system and how it will respond as the world heats up. A doomsday scenario involving the collapse of the circulation — previously portrayed in both peer-reviewed research and the climate disaster movie The Day After Tomorrow — came a lot closer in the last month. But rather than playing out in the far North Atlantic, as previously assumed, it now seems much more likely at the opposite end of the planet.
A new analysis by Australian and American researchers, using new and more detailed modeling of the oceans, predicts that the long-feared turn-off of the circulation will likely occur in the Southern Ocean, as billions of tons of ice melt on the land mass of Antarctica. And rather than being more than a century away, as models predict for the North Atlantic, it could happen within the next three decades.
Leading ocean and climate researchers not involved in the study who were contacted for comment praised the findings. “This is a really important paper,” says Stefan Rahmstorf, an oceanographer and head of earth system analysis at the Potsdam Institute for Climate Impact Research in Germany. “I think the method and model are convincing.”
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Read more: https://e360.yale.edu/features/climate-change-ocean-circulation-collapse-antarctica
The abstract of the paper;
Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater
Qian Li 1, Matthew H England 2, Andrew McC Hogg 3, Stephen R Rintoul 4 5, Adele K Morrison 6
The abyssal ocean circulation is a key component of the global meridional overturning circulation, cycling heat, carbon, oxygen and nutrients throughout the world ocean1,2. The strongest historical trend observed in the abyssal ocean is warming at high southern latitudes2-4, yet it is unclear what processes have driven this warming, and whether this warming is linked to a slowdown in the ocean’s overturning circulation. Furthermore, attributing change to specific drivers is difficult owing to limited measurements, and because coupled climate models exhibit biases in the region5-7. In addition, future change remains uncertain, with the latest coordinated climate model projections not accounting for dynamic ice-sheet melt. Here we use a transient forced high-resolution coupled ocean-sea-ice model to show that under a high-emissions scenario, abyssal warming is set to accelerate over the next 30 years. We find that meltwater input around Antarctica drives a contraction of Antarctic Bottom Water (AABW), opening a pathway that allows warm Circumpolar Deep Water greater access to the continental shelf. The reduction in AABW formation results in warming and ageing of the abyssal ocean, consistent with recent measurements. In contrast, projected wind and thermal forcing has little impact on the properties, age and volume of AABW. These results highlight the critical importance of Antarctic meltwater in setting the abyssal ocean overturning, with implications for global ocean biogeochemistry and climate that could last for centuries.
Read more: https://pubmed.ncbi.nlm.nih.gov/36991191/
Unless you are the kind of person who has a poster of Greta in your bedroom, global warming isn’t actually that scary. For most people, global warming would mean more BBQ weather, more time swimming in the pool, long summer walks.
But an abrupt return to ice age conditions would be truly scary and devastating – which is why “The Day After Tomorrow” was such a successful film. And it actually happened once, though circumstances were very different – today we don’t have a gigantic glacial lake caused by melting of the North American Ice Sheet, which is poised to collapse into the landlocked Arctic ocean, like we did last time.
Nevertheless the ice age claim is a sliver more plausible than most of the tipping point nonsense climate scientists push. Of course for any of this to happen, the Antarctic would need to actually warm. Robust warming has not exactly been a feature of the last century of Antarctic climate observations.
One benefit of making such predictions is that if global temperatures take a dive, scientists have it covered with an each way bet on the future trajectory of the global climate – though I’m not suggesting this is the motivation for such predictions.
Whatever happens, it will still all be our fault of course.
