The Atlantic Meridional Overturning Circulation (AMOC) is the global ocean circulation which is different from the well known Gulf Stream.
The Gulf Stream warms Europe and the Arctic, driven by surface winds and Coriolis forces. The AMOC is driven by cold salty water sinking in the North Atlantic. The AMOC is the main heat distribution system that has maintained the benign climate of the last ten thousand years. If that fails, as is likely, the Earth will probably, eventually fall into another ice age, as it has done many times.
Consider the recent paper in Nature by Peter Ditleven et al. This is a thorough review of the evidence and the probabilities of the AMOC collapsing.
They conclude the focus time for collapse of the AMOC is 2057 while the probability distribution goes from 2025 to 2095.
From 2025 !
No engineering project can restart the AMOC, we can call that a tipping point. This is an urgent matter. It is hard to predict what will happen with our warmed oceans. Sea levels will rise in the west coast of USA. Europe will cool while Africa heats, monsoons will change.
Agriculture will stumble, that is already happening. Hunger will force the migration of millions, many will starve or succumb to the heat.
Our civilisation will suffer stresses never seen before in the last few thousand years, not just volcanoes and Tsunamis, global changes. This is a Wake Up call.
We humans are responsible but we can make a floating mirror