AMOC Collapse Threatens National Security

Context

Recently, Iceland declared the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC) a direct threat to its national security and existence.

About the Atlantic Meridional Overturning Circulation (AMOC)

• It is a vast system of ocean currents that transports warm, salty water northward from tropical regions and returns cold, deep water southward. It is often called the "climate engine" of the Atlantic Ocean.
• It controls the movement of warm and cold water across vast ocean distances, affecting weather patterns, sea levels, and global temperatures.
• It is driven by differences in temperature (thermal) and salinity (haline), hence the term "thermohaline circulation."
• The most well-known component of the AMOC is the Gulf Stream, which carries warm water from the Gulf of Mexico across the North Atlantic to Europe.

Importance of the AMOC

• Regulates regional temperatures and keeps the climate mild, especially in Northern Europe.
• Distributes ocean nutrients and supports marine ecosystems and fisheries.
• Stabilizes weather patterns and reduces the frequency of extreme events.
• Regulates sea level, especially along the east coast of North America.

Signs of Weakening

In recent decades, scientists have observed signs that the AMOC is weakening. Key indicators include:

• Rapid melting of Greenland ice leads to an increase in freshwater in the North Atlantic, which disrupts salinity.
• Rising ocean temperatures alter density gradients and reduce the movement of water downstream.
• Changes in Atlantic sea-surface patterns have been observed through satellite and oceanographic data.
• According to a study in Nature Climate Change (2021), the AMOC is now at its weakest point in more than a millennium, indicating a potential tipping point.

Consequences of AMOC Collapse

• A complete or partial collapse of the AMOC could lead to severe and irreversible climate changes, including:
  • Harsher winters and shorter cropping seasons in Europe
  • Sea level rise along the US East Coast due to redistribution of ocean mass
  • Impacts on billions of people in Africa and Asia from disruptions in monsoon systems
  • Changes in marine biodiversity and the collapse of key fishing grounds
• These widespread impacts could destabilize economies, ecosystems, and even geopolitical relations.