Atlantic Meridional Overturning Circulation (AMOC)
Context:
Iceland recently designated the potential collapse of the Atlantic Meridional Overturning Circulation (AMOC) as a “national security threat and an existential threat"
This marks the first time a specific climate-related phenomenon has been formally brought before a National Security Council as a potential existential threat.
What is AMOC?
AMOC is a major component of the global ocean conveyor belt, responsible for transporting heat and nutrients across the Atlantic Ocean. It consists of a northward flow of warm, salty surface water and a southward flow of cold, dense deep water.
It is driven by temperature and salinity differences (thermohaline circulation).
It transports warm waters from tropical regions toward the Arctic thereby playing a crucial role in making winters in Northern Europe milder.
AMOC regulates Northern Hemisphere climate and global heat distribution and plays a role in the global carbon cycle, as deep-water formation stores heat and carbon
Key Drivers of Collapse:
The system is at risk due to the accelerated melting of ice sheets in Greenland and the thawing of the Arctic ice sheet
The influx of cold, fresh meltwater disrupts the balance of salinity and temperature that drives the current.
This influx is preventing the water from sinking and circulating effectively.
AMOC is considered a climate tipping element, meaning that beyond a certain threshold, the system could undergo irreversible changes leading to a complete collapse.
Potential Consequences:
A complete collapse could herald a modern-day ice age in Northern Europe
This can be characterized by severe cold temperatures, ice, and snow.
It could also cause summer drying and severe winter extremes in northwestern Europe.
Ocean impacts: Less deep-water formation leading to reduced carbon uptake.
Global Impact:
The collapse would shift tropical rainfall belts, severely disrupting rainfall patterns.
Countries from North Africa to India could face serious repercussions affecting farmers due to disrupted rainfall.
It would cut the ocean's northward heat supply
The last AMOC collapse occurred approximately 12,000 years ago
This was just before the start of human agriculture and modern civilization.
Predictions and Preparedness:
Recent studies suggest the AMOC has been weakening since 2004 and could potentially collapse between 2037 and 2109.
Early warning signals indicate the system started moving toward its tipping point around 1970
Iceland’s Response:
The government is preparing for potential consequences (including food insecurity, energy generation challenges, and disrupted sea transportation)
International Action:
Other nations like Ireland, Norway, and Finland have initiated research, while the UK has allocated funds to study climate tipping points.