What is the Atlantic Meridional Overturning Circulation and How Will It Impact the Globe?

The Atlantic meridional overturning circulation (AMOC) plays a pivotal role in regulating the climate of the North Atlantic region, making it a crucial component of the Earth's climate system. Recent observations have indicated a weakening in circulation, raising concerns about its stability in the face of ongoing climate change.

While assessments from the Intergovernmental Panel on Climate Change (IPCC) suggest that a complete collapse of the AMOC is unlikely within the 21st century, the potential for tipping into an undesirable state remains a significant concern as greenhouse gas concentrations continue to rise. 

What Is the Atlantic Meridional Overturning Circulation?

The movement of ocean water is governed by various currents, each influenced by several factors. Tidal currents, affected by the gravitational pull of the sun and moon, primarily occur near coastlines. Surface currents, on the other hand, are mainly driven by wind patterns across the ocean's surface. The process of thermohaline circulation differs, with the slower and deeper currents driven by changes in the ocean temperature and its salinity. This plays a crucial role in the global ocean circulation and is a part of the “global conveyor belt” --a vast interconnected system that includes the AMOC. The AMOC transports water with essential nutrients for marine life and redistributes warmth from north to south and back again in a continuous cycle within the Atlantic Ocean. 

This makes the AMOC a crucial component of the ocean’s circulation system. While the pacing of this process has always been slow, with each parcel of water taking 1,000 years to complete the journey, there are indications that the AMOC may be slowing down even further. Research funded by the NOAA aims to investigate the AMOC’s role in coastal sea level changes and its connection to extreme weather events. The main concern of experts is this shift in speed leading to the AMOC’s collapse.

What Does It Mean if the AMOC Collapses?

If the AMOC were to collapse, the consequences would be profound, albeit not as sudden or dramatic as depicted in movies. Heat distribution patterns would shift, resulting in warming in the Southern Hemisphere, particularly affecting regions like South America and Australia, while Western Europe would experience cooling over the span of about 100 years, with temperatures potentially decreasing by 5 to 10 degrees Celsius. 

While some may welcome the prospect of cooler temperatures, the reality could be harsh, especially in areas experiencing rapid cooling. For example, in Bergen, Norway, temperature measurements for February suggest a staggering decline of up to 35 degrees per century, a change deemed "really crazy" by experts. Although an ice age scenario akin to The Day After Tomorrow is unlikely, the cooling trend would still be significant. Furthermore, rising sea levels would disproportionately affect the East Coast of the United States.

How Can Journalists Report on This Phenomenon?

Reporting on the AMOC will require journalists to convey its significance in regulating the climate, its recent observations indicating weakening, and the potential implications of its collapse.

Journalists can explain the basics of the AMOC to any readers that do not know about it while emphasizing its position as a critical component of the Earth’s climate system. It may be beneficial to also address any misconceptions or sensationalized portrayals of the AMOC collapse, such as those depicted in moves like the aforementioned The Day After Tomorrow and emphasize the gradual nature of potential changes, prompting the need for evidence-based reporting. It is also important to highlight the potential societal impacts of AMOC changes, such as disruptions to agriculture, coastal communities, and global economies.

Overall, a journalist’s readers should ultimately be encouraged to stay informed and engaged with ongoing developments in climate science.