Indian Ocean Warming Accelerates: A Cause for Concern

For Prelims: Global warming, Indian Ocean, Heatwave state, Coral bleaching, Seagrass, Kelp forests, Fisheries sector, Indian Ocean Dipole (IOD)

For Mains: Reasons for Ocean Warming, Heatwaves and Effects, Sea Level Rise

Why in News:

• A recent study by the Indian Institute of Tropical Meteorology (IITM) in Pune highlights a tenfold increase in marine heatwaves, potentially intensifying cyclones

About: –

• The Indian Ocean is experiencing a period of rapid warming, with significant consequences for weather patterns, marine ecosystems, and coastal communities

Key Findings:

• Ocean Temperature Rise: The Indian Ocean’s temperature has risen by 1.2°C since 1950 and is projected to increase further by 1.7°C to 3.8°C by 2100.
• Marine Heatwaves: The number of marine heatwave days is expected to jump from an average of 20 per year to a staggering 220-250 days per year. These heatwaves are linked to faster cyclone formation and could push the tropical Indian Ocean into a near-permanent heatwave state.
• Impact on Marine Life: Frequent and intense heatwaves are likely to accelerate coral bleaching, destroy seagrass meadows, and damage kelp forests, all crucial for the fishing industry.

Deep Ocean Warming:

• The warming extends beyond the surface, reaching depths of 2,000 meters. This escalation in the ocean’s overall heat content is concerning.
• The rate of heat content increase is projected to grow significantly in the future, equivalent to the energy released by one Hiroshima bomb detonation every second for ten years.

Sea Level Rise and Thermal Expansion:

• Increasing heat content leads to sea-level rise, primarily through thermal expansion. This thermal expansion is the biggest contributor to sea-level rise in the Indian Ocean, surpassing the effects of melting glaciers and ice sheets.

Changes in Monsoon Patterns:

• The rise in ocean heat content is expected to alter the Indian Ocean Dipole (IOD), a major factor influencing monsoon strength.
• Extreme IOD events, linked to positive phases with warmer western waters, are predicted to increase by 66%, while moderate events may decrease by 52% by the end of the 21st century.

Future Outlook:

• Despite ongoing heatwaves, an “above-normal” monsoon is expected for June-September 2024, partly due to a current positive IOD phase.

Understanding the Difference: Land vs. Marine Heatwaves

Land heatwaves and marine heatwaves differ in several ways:

• Medium: Land heatwaves affect air temperature, while marine heatwaves impact ocean surface water temperature.
• Duration: Land heatwaves typically last for days or weeks, while marine heatwaves can persist for weeks or even months.
• Identification: Land heatwaves are identified by exceeding high-temperature thresholds, while marine heatwaves are characterized by abnormally high sea surface temperatures.
• Impacts: Land heatwaves cause heat stress, dehydration, wildfires, and power outages. Marine heatwaves disrupt marine ecosystems, harm marine life, and influence weather patterns, potentially intensifying cyclones.

How Rising Sea Levels Impact India:

• India’s coastlines are particularly vulnerable to rising sea levels due to several factors:
  • The rapid warming of the Indian Ocean, causing significant thermal expansion.
  • The Indian Ocean being the fastest warming ocean in terms of surface temperature.
• The rate of sea level rise along the Indian coast is about 1.7 mm/year.
• A sea level rise of 3 cm could cause seawater intrusion inland by about 17 meters.
• India faces compounding extreme events like intensifying cyclones due to more moisture and heat from ocean warming.
• Storm surges combined with rising sea levels are increasing the extent and severity of flooding.
• Cyclones are bringing more rain, leading to situations like Cyclone Amphan (2020) which caused large-scale flooding and saltwater intrusion.
• Rising sea levels threaten the future of major deltas like Indus, Ganga, and Brahmaputra, as saltwater intrusion may render vast areas uninhabitable.

Steps Taken by India:

• Monitoring and Research: Indian National Centre for Ocean Information Services (INCOIS) plays a crucial role in monitoring the Indian Ocean.
• Cyclone Preparedness: National Disaster Management Authority (NDMA) and IMD cyclone warnings help prepare for cyclones.
• Additional Measures:
  • National Missions on Climate Change
  • Coalition for Disaster Resilient Infrastructure
  • Renewable Energy Target
  • National Hydrogen Mission
  • Amrit Dharohar Scheme (a wetland conservation program)

Tackling the Threat:

• Mitigation Strategies:
  • Emission Reduction Policies: Adopting policies like the European Union’s Emissions Trading System (ETS) can incentivize industries to reduce greenhouse gas emissions, the root cause of marine heatwaves.