Volcanic Eruptions Emerge as New Factor in AMOC Stability Threat

The Atlantic Meridional Overturning Circulation (AMOC) plays a crucial role in maintaining Northern Europe's mild climate, including Denmark, by transporting warm water northward from the Southern Hemisphere. A potential collapse of this vital ocean current could drastically alter weather patterns.

Winter temperatures in Denmark could potentially plummet to minus 35 degrees Celsius if the AMOC were to collapse.

Global Warming and Existing Concerns

Currently, global warming and increased meltwater from the Arctic are recognized threats to the AMOC's stability. However, the scientific community continues to grapple with disagreements regarding the exact extent of this threat, the likelihood of a complete collapse, and the potential timeline for such a catastrophic event.

New Research Introduces Volcanic Influence

A new study, conducted by an international research team including scientists from the Niels Bohr Institute at the University of Copenhagen, has introduced an additional, previously underappreciated factor capable of influencing the AMOC: volcanic eruptions.

Professor Markus Jochum, a co-author of the study, highlighted the implications of this finding:

"The AMOC might be more sensitive to external influences, such as volcanic eruptions, than previously believed."

Unveiling Historical Links and Mechanisms

The research utilized a sophisticated combination of ice core data and climate models to demonstrate how extreme volcanic eruptions can disrupt the climate system and potentially weaken or even cause a complete collapse of the AMOC.

Guido Vettoretti, lead author from the Niels Bohr Institute, explained the historical context:

"Historically, large volcanic eruptions near the equator have been linked to collapses in the Atlantic Ocean current, which could trigger sudden climate changes lasting for millennia."

The mechanism behind this influence is rooted in the atmospheric impact of major eruptions. Large volcanic eruptions release significant amounts of sulfur and dust into the atmosphere and stratosphere, which reduces solar radiation reaching Earth's surface and initiates a cooling effect. This cooling process, in turn, leads to increased sea ice formation and changes in ocean salinity. Ultimately, these alterations impact the AMOC's fundamental mechanism of warm water transport.

Implications for Climate Shifts and Tipping Points

The study suggests that very large volcanic eruptions could be a significant cause for profound climate shifts lasting over centuries or even millennia, particularly when the climate system is already nearing a critical threshold. This scenario bears resemblance to conditions observed during periods of global warming.

This newly identified mechanism also offers a potential explanation for the rapid shifts between cold and warm periods, known as Dansgaard-Oeschger events, which occurred during the last ice age. Professor Jochum summarized the critical role of volcanoes in such scenarios:

"If the system is close to a tipping point, a volcanic eruption could serve as the catalyst."