I’ve written before on the dangers that confront us should the Atlantic Meridional Overturning Circulation (AMOC) collapse, but the release of a new report raises the stakes.
The AMOC is the Atlantic’s conveyor belt bringing warm saline water from the tropics (because of the higher rate of evaporation in the tropics, salinity is increased) to the North Atlantic. When that water meets the North Atlantic it cools, sinks, and starts its path back in a loop to the tropics. The action is critical in exchanging heat, nutrients, salinity, carbon capture (carbon sink), to maintain the ocean’s ecosystem. It is what keeps England and Europe warmer than their latitudes would otherwise permit.
Why is the AMOC a concern? It has been weakening dramatically. A few years ago, models showed the risk of its collapse at 10%. The new study, published in the journal Environmental Research Letters assessed the numerous models used by the United Nation’s Intergovernmental Panel on Climate Change.
The findings are alarming. Models now show that the tipping point where the AMOC shuts down is nearly inevitable. Even at low-emission scenarios, a 25% chance is assigned to the collapse of AMOC by 2100. The high emission model has those odds at 70% and not 50-100 years down the road but as early as 2050-2070. In our children’s lives.
What would happen? The result would be a shift in the tropical rain belt that hundreds of millions rely on for food production. Europe would face extreme cold, as much as a 10-15˚F shift. Winter ice could result as far south as the British Isles. In the United States, far colder winters would occur with disruptions to rainfall patterns interrupting the agricultural industry that is the backbone of the northern plains states. Adaption in parts of the Northern Hemisphere would be impossible forcing migration and the loss of traditional forms of agriculture. And the shift would occur rapidly. We aren’t talking the apocalyptic scenes from the movie The Day After Tomorrow, but a horror show it would be.
Again, what I want to stress is this isn’t a left versus right issue, it’s an economic and national security issue. It’s better to view these warnings in terms of stock portfolios, 401ks, the culture of the American farmer, and the costs of groceries than in left versus right terms. In the end we are all in the same damn boat (which we might need as a loss of AMOC is projected to increase sea level rise on the Eastern seaboard of the United States by as much as two feet).
Personally, I would go with the 25% rather than the 70% odds.