ATLANTIC OCEAN CURRENT WEAKENING

ATLANTIC OCEAN CURRENT WEAKENING

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

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