Scientists from the University of Bordeaux say in a new study that AMOC is on track to weaken 50% by the end of this century. Their model, published in Science Advances, corrects temperature and salinity biases, showing a sharply increased rate of AMOC slowdown. This slowdown could lead to extensive drying in Africa's drought and famine-stricken Sahel region, while temperatures in the Northern Hemisphere will plummet as the Gulf Stream fails to bring warm water up from the Tropics. The Atlantic Meridional Overturning Circulation (AMOC) is a vast network of ocean currents that drives warm water northwards through the Gulf Stream.
Earlier studies underestimated how fast AMOC is slowing down due to optimistic assumptions about ocean surface temperature and salinity. Scientists previously thought AMOC would only reduce in strength by around 32% over this time period. Fresh water from melting glaciers is making water around the poles less dense, gradually slowing the AMOC's steady flow.
Even though the future of AMOC is uncertain, the potential for a rapid weakening or collapse is a risk that we must take seriously, especially in the Nordic region where the consequences could have major societal effects.
According to the latest IPCC report, continued global warming will very likely lead to a weakening of AMOC, but with medium confidence not to an abrupt and complete collapse before 2100. AMOC plays a key role in the relatively mild climate in northern Europe. New research after the 2023 IPCC report suggests the risk of passing a tipping point for AMOC before 2100, and an almost complete collapse during the 22nd century, is a real possibility.
The report 'A Nordic Perspective on AMOC Tipping' assesses robust effects including general cooling of the North Atlantic and surrounding areas, sea level rise in northern Europe, and changes in tropical precipitation patterns. If AMOC collapses, the main and dominant signal will be cooling compared to the warming level prevailing when the collapse occurs. Other effects, such as the extent of both winter and summer cooling, are more uncertain. A collapse of AMOC could trigger extreme consequences in Nordic countries that differ from, and partly counteract, those expected from global climate change.
The report identifies important knowledge gaps, particularly regarding sector-specific consequences, such as effects on food production, energy systems, and other climate-sensitive sectors in Nordic countries. Its key messages include the need for strong emission reductions to achieve reduced fossil fuel use and net-zero emissions, and long-term funding for observation networks and an early warning system for AMOC. According to climate researcher René Navarro-Labastida at SMHI and one of the report's authors, the potential for a rapid weakening or collapse is a risk that must be taken seriously, especially in the Nordic region where the consequences could have major societal effects. The exact timeline for when AMOC might reach a tipping point or collapse remains unclear, as does how severe the cooling in the Northern Hemisphere will be if AMOC weakens or collapses. Specific impacts on food production and energy systems in Nordic countries are also uncertain, along with the extent to which changes in AMOC will affect global weather patterns beyond the Northern Hemisphere and Sahel region.