Climate chaos: Europe could freeze or sizzle if Atlantic currents go awry

But what if the climate crisis instead plunges us into a world of frozen winters and parched summers, rendering those agricultural investments worthless? This risk has been greatly underestimated, as well as poorly communicated—and [for Europe] it all depends on what happens in the Atlantic Ocean.

[The European] weather system relies on the Atlantic Meridional Overturning Circulation (AMOC). This vital ocean-current system transports warm water northwards before returning south with a flow of deep, cold water. The resulting heat transfer helps western Europe remain much milder than other places on the same latitudes, such as Siberia, while also playing a role in global rainfall patterns and phytoplankton distribution (and therefore fish stocks and underwater biodiversity).

But by burning fossil fuels, humans have put the vast marine conveyor belt at risk. Driven both by temperature and salinity, the AMOC is poised to weaken as oceans get warmer and vast amounts of freshwater from the melting Greenland ice sheet dilutes the North Atlantic. Scientists consider it a potential tipping element: We could reach a point where feedback loops take over and cause an abrupt change in a system—the collapse of the AMOC.

There’s a tonne of uncertainty involved, including the level of global warming at which irreversible changes start taking place and the timescale over which a shutdown could occur. Data collection only began in 2004, so it’s hard to separate long-term trends from short-term variability.

Studies—such as a January 2025 paper that said the AMOC had not slowed down in the last 60 years and a 2018 study suggesting it has—use climate models to fill in the gaps. While there’s evidence that the AMOC has weakened, such as the emergence of a ‘cold blob’ just south of Greenland, disagreement between published studies have made it harder to quantify the risk.

Scientists agree that it’s definitely capable of collapse—it’s had sudden shifts between weak and strong modes several times during the last 70,000 years—and that the impact would be dire.

But it’s easier to ignore something when the science appears to be so inconclusive. In just the past year, here are some contradictory takeaways from various studies: October 2024: “The Atlantic Ocean’s currents are on the verge of collapse." January 2025: AMOC has not declined in the last 60 years. February 2025: “Total collapse of vital Atlantic currents unlikely this century." August 2025: “The collapse of a critical Atlantic current can no longer be considered a low-likelihood event."

Listing conclusions like this makes it seem like the consensus is wildly swinging from one side to the other, but each of these papers adds a piece to what oceanographer and climatologist Stefan Rahmstorf calls the “huge jigsaw puzzle" of scientific understanding on the blog RealClimate.

For instance, the February paper published in Nature, led by Met Office scientist Jonathan Baker, seems to contradict studies warning that the AMOC is getting closer to the all-important tipping point. But the difference lies in semantics—the degree of weakening classified as a “collapse" in the most recent paper, on which Rahmstorf is an author, is deemed “not a collapse" in the earlier article.

Is that reassuring? Not to me. A weakened AMOC would have huge ramifications for the planet such as harsher European winters, an acceleration in rising sea levels and fiercer hurricanes. But media coverage lingered on Baker’s statement that the ocean-current system is “safe from climate collapse" rather than the nuances.

The more recent paper, published in Environmental Research Letters, extends beyond 2100, using climate models to predict what might happen under various emissions scenarios by 2300 and 2500. If carbon emissions continue to rise, 70% of the projections see the AMOC collapse by 2300. If we stick to our Paris Agreement promises, a shutdown still happens 25% of the time.

When scientists are unsure or the risk seems low, it’s tempting not to worry. But when potentially catastrophic impacts are involved—If the plane you were boarding had a 25% chance of crashing, would you fly?—then a precautionary approach is warranted.

Paying closer attention to the Atlantic Ocean may give the world enough of a fright to force us to take the climate crisis a lot more seriously. ©Bloomberg

The author is a Bloomberg Opinion columnist covering climate change.