Why in News
  • Recent studies show that the Atlantic Meridional Overturning Circulation (AMOC) is steadily weakening
  • Scientists warn that a possible collapse could:
    • Increase global warming
    • Disrupt climate systems worldwide
  • Research published in scientific journals highlights:
    • Risk of tipping point behaviour
This is a major concern for global climate stability

WHAT IS AMOC?

  • AMOC (Atlantic Meridional Overturning Circulation) is a system of:
    • Ocean currents acting like a conveyor belt
How it Works
  • Warm surface water moves:
    • From tropics ? North Atlantic (Arctic region)
  • Cold dense water sinks and returns:
    • From North Atlantic ? tropics (deep ocean currents)
This circulation helps in:
  • Regulating global climate
  • Maintaining temperature balance

IMPORTANCE OF AMOC

  • Controls:
    • Climate of Europe and North America
  • Helps in:
    • Heat distribution across Earth
  • Acts as:
    • A climate stabilising system
Tipping Element
  • AMOC is one of the Earth’s climate tipping elements
Meaning:
  • It can undergo sudden and irreversible change

EVIDENCE OF WEAKENING

  • Observations over the last two decades show:
    • Continuous decline in AMOC strength
  • Data collected from:
    • Multiple ocean monitoring systems (mooring arrays)
  • Strongest decline observed at:
    • Around 5°N latitude
Indicates AMOC may be approaching a tipping point

CAUSES OF AMOC WEAKENING

(A) Global Warming
  • Increase in greenhouse gases raises temperature
(B) Melting of Greenland Ice Sheet
  • Releases large amounts of freshwater into ocean
(C) Reduction in Salinity
  • Freshwater reduces:
    • Salt concentration (salinity)
  • This affects:
    • Water density
    • Ocean circulation
Key Problem:
  • Weakens the sinking process of cold water

RISK OF COLLAPSE

  • Studies suggest collapse could occur between:
    • 2037 and 2109
  • Even without additional warming:
    • Collapse is still possible
Recovery may not occur in a warming world

IMPACT OF AMOC COLLAPSE

(A) Global Warming Increase
  • Additional warming:
    • Around 2°C globally
(B) Carbon Cycle Disruption
  • Release of:
    • 47–83 gigatonnes of CO2
  • Southern Ocean may change from:
    • Carbon sink ? Carbon source
(C) Regional Temperature Changes Northern Hemisphere
  • Arctic cooling:
    • Up to 7°C decrease
  • Cause:
    • Reduced heat transport
Southern Hemisphere
  • Antarctica warming:
    • Up to 6–10°C increase
(D) Climate Imbalance
  • Uneven temperature distribution
  • Disruption of:
    • Weather patterns
    • Ocean systems

SEA ICE ALBEDO FEEDBACK

  • Ice reflects more sunlight than water
  • More cooling leads to:
    • More ice formation
  • More ice increases:
    • Reflection (albedo)
This creates a feedback loop of further cooling

SCIENTIFIC MODELLING

  • Scientists used:
    • CLIMBER-X climate model
  • Simulation method:
    • Added freshwater to North Atlantic
    • Adjusted salinity globally
Key Findings
  • AMOC can collapse:
    • Even without major warming
  • Recovery is:
    • Difficult in current climate conditions

BROADER IMPLICATIONS

  • Risk of:
    • Abrupt climate change
  • Impacts on:
    • Agriculture
    • Fisheries
    • Ecosystems
  • Could trigger:
    • Chain reactions in climate system

CHALLENGES IN MONITORING

  • Difficult to:
    • Measure ocean circulation continuously
  • Scientists use:
    • Ocean Bottom Pressure (OBP) data
Need for:
  • Better long-term monitoring systems