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  • Writer's pictureGregory Andrews

Atlantic Meridional Ocean Current Collapse: What Is It? Why We Should Worry

The Atlantic Meridional Overturning Circulation (AMOC) might sound technical and abstract, but is actually a really important part of Earth's climate system. It's something we all need to know about. Akin to a global heat pump for the planet, the AMOC circulates warm, ocean waters from the tropics up to the North Atlantic, where it cools against the ice and then sinks and returns southward at deeper ocean levels. The AMOC is like a conveyor belt that transfers warm water north and cool water south. It maintains weather patterns, not only in Europe and North America, but even in Asia and Australia. It plays a vital role in regulating and stabilising the global climate.

By transporting heat from the Equator to higher latitudes, the AMOC helps maintain relatively mild temperatures in northern Europe. And through its interaction with the Indian and Pacific Oceans, the AMOC influences rainfall and weather patterns in our region. It influences vital monsoon systems in Asia. A stable AMOC thus supports the global climate, moderating extreme weather and sustaining ocean systems on which we all depend.

The Threat of Tipping Points

Recent studies and analysis from leading scientific organisations like the Potsdam Institute for Climate Impact Research, have raised serious alarms about the AMOC's stability. The AMOC is showing serious signs of weakening, and there are real indications that it is approaching a tipping point. This refers to critical thresholds beyond which the AMOC will undergo abrupt and possibly irreversible changes, leading to a cascade of global climate disruptions. It has happened in the past.

Collapse of the AMOC would have profound consequences. For northern Europe in particular, it would mean a huge drop in temperatures. This would disrupt agriculture, food production, livelihoods and security. Globally, the implications would also include shifts in weather patterns, including major changes in the intensity and frequency of tropical storms closer to the Equator The climate system's complex interdependencies mean AMOC collapse effects would ripple out across the globe, exacerbating existing climate challenges, including in Australia.

Scientific Insights

Understanding the precise behavior and future trajectory of the AMOC is a significant challenge. It's complexity requires advanced modeling techniques and extensive paleoclimatic data to identify early warning signals of tipping points. Research using high-resolution models to simulate the AMOC's dynamics has identified multiple states it can occupy. This multistability suggests the AMOC can shift between different states rapidly.

A study led by scientists from the Niels Bohr Institute also highlighted the possibility of intermediate tipping points. These smaller, incremental changes might not immediately cause a full collapse, but could progressively push the system towards a critical threshold. Think of it like a Jenga tower: removing one block might not cause the entire tower to fall, but the risk of collapse increases signficantly as each subsequent block is removed.

Why Australia Should Worry

The science shows collapse of the AMOC is not just a theoretical concern; it is a clear and present danger. The current trajectory of global warming is increasing the risk of AMOC collapse. The resulting climate shifts would not only be beyond our control but would likely to occur on much shorter timescales than previously anticipated.

Collapse of the AMOC would have drastic consequences for food security and the cost-of-living. An AMOC collapse would result in a significant cooling of up to 15°C in northern Europe, leading to much harsher winters there. This would severely impact agricultural productivity in that part of the world, reducing growing seasons and crop yields. Freezing temperatures would also exacerbate energy demands for heating, increasing costs for households and businesses. The rapidly altered climate would also disrupt ecosystems and biodiversity, affecting fisheries and marine life that Europeans depend on for their livelihoods. The overall economic impact would be profound, with declines in tourism, increased healthcare costs due to cold-related illnesses, and strained public services.

Developments in Europe would have major spill over effects for Australia. On a global scale, AMOC collapse would disrupt weather patterns, leading to more extreme weather events such as stronger storms and altered precipitation patterns in our region. This would affect water resources, food production, and infrastructure resilience. Regions that depend on stable monsoons, such as Australia's north and South Asia, could face devastating impacts on agriculture and food security​​. And from a strategic security perspective, climatic changes would almost certainly exacerbate existing tensions over resources and increase the frequency and intensity of humanitarian crises and mass migration flows.

Even in Aotearoa New Zealand, which is about as far from the AMOC as it's possible to get, the impacts of its collapse would be significant. A scientific assessment published in The Conversation showed NZ would suffer extreme weather events, storms and unusual temperature fluctuations, and this would disrupt food production, marine ecosystems, fisheries and biodiversity there.

How Close Is The AMOC To Collapse?

The AMOC is already slowing down. When it reaches a critical point, it could transition abruptly, much like a Jenga Tower collapse, rather than continued gradual decline​. Scientists have already identified several early warning signs of a potential AMOC collapse, including its slow-down and significant changes in ocean salinity and temperatures. There's a chance that the AMOC could collapse within the next decade. And unless emissions come down rapidly, it almost certainly will collapse within the lives of our children.

So, yes, we should be very worried about AMOC collapse. Even in Australia, the repercussions will be felt through heightened climate variability, major economic and trade disruptions, and strained social and strategic relations. The cascading effects would destabilise global food security and amplify conflicts over resources and migration. With the potential for abrupt changes occurring within the next few decades, it's imperative that we take immediate and decisive action to address the climate crisis head-on and prepare for a future where drastic shifts are a real possibility.

Map: NASA.

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