The ocean circulation that persists even after a key AMOC component fails
The Atlantic meridional overturning circulation (AMOC) is thought to face a potentially existential threat from climate change. But attempts to model what happens to AMOC as the oceans warm show divergent outcomes, leaving its fate unclear. In a paper published in AGU Advances, Shantong Sun and Andrew Thompson use a hierarchy of models to show that the cross-hemispheric overturning could persist…
A recent study in AGU Advances explores the persistence of ocean circulation even after a significant component of the Atlantic Meridional Overturning Circulation (AMOC) ceases. The Atlantic meridional overturning circulation plays a critical role in regulating global climate. Climate change poses a potential threat to its stability. In this research, scientists employed multiple models to understand the behavior of the ocean circulation system when its key component, North Atlantic Deep Water (NADW) formation, shuts down.
The research used the Community Earth System Model 2 (CESM2) from the National Center for Atmospheric Research, simulating a high carbon dioxide scenario where the formation of NADW ceases. The model showed that the cross-hemispheric overturning could persist for centuries, not due to a continuous balance of sinking and rising water, but rather due to a gradual deepening of ocean density layers.
This finding suggests that while the circulation may appear active for centuries, it may not endure indefinitely. The deepening mechanism simply maintains the circulation for several centuries until the ocean reaches a new density distribution. However, predicting the future of AMOC remains challenging, and the study's authors caution against overinterpretation.
The research also reveals an emerging clockwise overturning circulation in the Indo-Pacific Ocean, a phenomenon that could redistribute heat, biogeochemical tracers, and ventilation throughout the ocean. This could result in cooler surface temperatures at the cost of intermediate water layers, and a decrease in nutrient-rich water in the upper ocean.
Furthermore, the deep Atlantic's ventilation age—indicating the time since a water mass has been in contact with the atmosphere—could increase substantially. These changes could have far-reaching implications, including shifts in global nutrient and ventilation patterns, which may impact ecosystems and global climate.
Written by urgent.news from Phys.org's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
This story
This is one outlet's version. Read the fullest account.
