Potential collapse of the Atlantic Ocean Circulation strongly affects European climate
"Climate impacts would be nearly irreversible on human timescales”
Researchers from Utrecht University have successfully simulated the collapse of the large-scale ocean circulation in the Atlantic Ocean using a complex climate model, revealing severe global climate repercussions with Europe bearing the brunt. They published their findings in the scientific journal Science Advances today.
The Atlantic meridional overturning circulation is an important component in the global climate system, redistributing heat through the ocean and regulating global and regional climates. Alarming trends indicate a gradual decline in its strength over recent decades, raising concerns of an abrupt weakening under future climate conditions. Researchers observed these abrupt changes in simplified climate models, but not yet when using the latest generation of state-of-the-art climate models.
The research team, consisting of Henk Dijkstra, Michael Kliphuis, and René van Westen, designed a simulation in which they were able to measure a sudden weakening of the ocean circulation. In the simulation, they introduced a freshwater force into the Atlantic Ocean. As a result, the circulation strength gradually decreased until it reached a critical tipping point and collapsed.
Impact on the European climate
We were amazed by the transient responses and climate impacts of the Atlantic Ocean circulation collapse, van Westen says. In their simulation, the European climate cools by about 1 °C per decade, and some regions even experience over 3 °C cooling per decade.
Comparing these figures to the current global warming rate of 0.2°C per decade underscores the unprecedented nature of the climate impacts during a tipping event.
Cooler temperatures over Europe may seem positive, but the repercussions are far-reaching, with other regions experiencing accelerated warming and altered precipitation patterns. Additionally, a 100 cm rise in European sea levels is projected due to the abrupt ocean circulation collapse, Van Westen warns.
Cooler temperatures over Europe may seem positive, but the repercussions are far-reaching, with other regions experiencing accelerated warming and altered precipitation patterns.
Early warning system
Addressing the uncertainty surrounding the proximity of the real ocean circulation to its tipping point, Dijkstra emphasizes the need for a physics-based and measurable early warning indicator. Dijkstra:
Current observational records are too short to make a reliable estimation, but the early warning indicator shows that we are moving in the direction of the tipping point.
Van Westen underscores the urgency of the situation:
Once the Atlantic Ocean circulation collapses, the resulting climate impacts are nearly irreversible on human timescales, as our earlier research has shown. Dijkstra adds:
Staying clear of this tipping point is imperative for avoiding devastating consequences on climate, society, and the environment.
"Staying clear of this tipping point is imperative for avoiding devastating consequences on climate, society, and the environment."