Not if, but when: The coming North Atlantic deep freeze

In recent years scientists have been watching and measuring the flow of the Atlantic Meridional Overturning Circulation, (AMOC), what Americans often refer to as the Gulf Stream though that flow is only part of this vast ocean current. For a long time the belief was that the AMOC—which transports heat from the tropics to Greenland, Iceland and northern Europe and makes them much warmer than they would otherwise be—would continue to flow with no discernible end date.

But two recent studies suggest that the current could not just slow, but stop altogether sometime around mid-century thereby lowering temperatures dramatically in northern Europe. The earlier study from 2023 suggests a collapse could occur sometime between 2025 and 2095, a wide interval, but actually the blink of an eye in geologic time. The more recent study released this year used a more sophisticated model and narrowed the window from 2037 to 2064. Both studies put the most likely date of collapse at mid-century (either 2050 or 2057).

Rising temperatures due to climate change are resulting in vastly increased meltwater coming from the the Greenland ice sheet—which on average is over one mile thick. This meltwater is being dumped into the North Atlantic where it reduces the salinity of the ocean water, thus making the water less dense. This reduced density appears to be slowing the current where it dives deep into the ocean, a dive that is essential for the current to continue to flow.

Meanwhile, business as usual continues in northern Europe and the rest of the world, too. Greenhouse gases are now accumulating in the atmosphere at a record pace. Far from addressing our climate crisis, we as a species are behaving as if it doesn’t exist (even though in many places leaders give lip service to doing something while they do nothing commensurate with the danger we face).

Cheerleaders for the so-called energy transition love to talk about how carbon dioxide emissions have “decoupled” from economic growth. By this they generally mean that per capita emissions are declining compared to per capita economic growth. And, while some countries have shown actual declines in the RATE of emissions, that does NOT mean that they are at zero emissions. They continue to contribute to the stock of carbon in the atmosphere at prodigious rates. And, the world as a whole still needs to burn ever increasing amounts of carbon to grow.

That makes me believe that the deep freeze in the North Atlantic will more likely than not arrive on schedule. We have no plan to avert it and simply wearing warmer clothing is not going to address the myriad problems that societies unprepared for sudden climate change will suffer.