Gaby
Danish scientists have issued a paradoxical forecast about our continued reliance on energy sources that emit greenhouse gases. They warn that critical ocean currents that move heat, cold, and precipitation between the tropics and the North Atlantic could shut down by about 2060 if emissions stay on their current path. This calculation contradicts previous reports from the Intergovernmental Panel on Climate Change (IPCC).
As Europe braces for the impacts of climate change, one might picture a future of more extreme heat. But a recent study by Danish researchers paints a different picture: the Atlantic Meridional Overturning Current (AMOC)—the system of ocean currents that redistributes heat and cold between the North Atlantic and the tropics—could stop functioning entirely unless greenhouse gas emissions are reduced. The researchers used complex statistical tools to analyze ocean temperature records spanning the past 150 years. They determined with 95% confidence that the AMOC could collapse sometime between 2025 and 2095, with their best estimate centered on 2057.
The shutdown of the AMOC would create wide-ranging problems, from intensified warming in the tropics to more frequent storms in the North Atlantic. Professor Peter Ditlevsen says this would have serious consequences for Earth’s climate. For example, a halt in thermohaline circulation would change how heat and precipitation are distributed around the planet. Although Europe might not experience dramatic cooling—global warming and more frequent heatwaves could offset local cooling—the AMOC’s collapse would amplify warming in the tropics, where higher temperatures are already making life harder.
Professor Ditlevsen says their results highlight the urgent need to cut greenhouse gas emissions worldwide. But these calculations challenge the latest IPCC assessment, which concludes that a sudden change in thermohaline circulation is unlikely this century based on climate models. The researchers based their prediction on early-warning signals that ocean currents emit as they begin to destabilize—signals scientists have observed before. They say recent advances in statistical methods make it possible to estimate a collapse timeline more precisely than was previously feasible.
The team analyzed sea-surface temperatures in a specific region of the North Atlantic from 1870 to the present. That lets them treat those temperature fluctuations as “fingerprints” of AMOC strength, which is useful because direct measurements of the AMOC exist for only the last 15 years. Professor Susanne Ditlevsen said the new statistical tools produce more reliable estimates, giving scientists a clearer picture of when a thermohaline collapse is most likely—something that wasn’t possible before.
The AMOC has been relatively stable since the end of the last ice age, although it collapsed repeatedly during the ice-age period. This collapse, known as the Dansgaard-Oeschger event, appears in Greenland ice cores and happened about 25 times during the ice age. As noted by Earth, those events brought extreme climate swings, with temperatures shifting by 10–15 degrees over roughly a decade. By contrast, today’s warming is on the order of 1.5 degrees over a century. With the risk of another collapse looming, cutting greenhouse gas emissions becomes even more urgent.
