A weakening Atlantic current could reroute the storms California depends on

A new study projects that a slowing AMOC would push more atmospheric rivers onto North America's west coast by century's end.

Researchers publishing in Nature Communications have modeled what happens to weather patterns if the Atlantic Meridional Overturning Circulation (AMOC) continues to weaken. The AMOC carries warm tropical water north toward Europe and returns cooled water south along the seafloor. Lead author Mohima Mimi, a climate dynamics researcher at the University of California, Riverside, and colleagues combined decades of NASA atmospheric data with climate simulations to project the current's evolution.

The study finds that a weaker AMOC would strengthen storms along parts of North America, particularly the California coast, while reducing storm activity over Greenland and the Arctic. A central mechanism is atmospheric rivers, the narrow bands of concentrated water vapor that can carry many times the flow of the Mississippi and already supply up to half of the annual rainfall in the western US. The study projects global mean atmospheric river frequency could rise by roughly 50 percent, with the largest increases stretching from Baja California to Alaska.

For water, food, and coastal life, this cuts two ways. More atmospheric rivers can mean both critical rainfall and destructive flooding, while shifting patterns could destabilize the summer meltwater that feeds West Antarctic ice shelves. Abundance depends on predictable climate; a reorganized one strains agriculture, housing, and freshwater supply.

The caveats matter. These are simulations, not observed outcomes, and the result hinges on future greenhouse gas emissions. The timing and likelihood of an AMOC collapse remain debated among scientists. Watch whether independent modeling groups reproduce the projected atmospheric-river shift.

Source: ScienceAlert