The system of currents that keeps northwestern Europe relatively mild is already weakening. Illustration shows Atlantic surface currents and eddies, with arrows showing the AMOC's warm northward surface flow and cold southward return flow at depth. Credit: Brenden Jongman / NASA and NOAA data / AMOC

Icelandic government officials recently met to discuss a dramatic scenario: what if the current that circulates Atlantic waters weakened significantly, or collapsed altogether?

The ocean currents are changing, with major implications for climate around the world. Yet our new article published in Nature Sustainability suggests most governments are not preparing for this possibility. Of 91 national adaptation plans submitted to the U.N.…