Indian Ocean Warming Accelerates | 01 May 2024

Source: TH

Why in News?

Recently, an Indian Institute of Tropical Meteorology (IITM), Pune indicates a tenfold increase in marine heatwaves, potentially intensifying cyclones, with a rise from 20 days to 220–250 days per year.

What are the Key Findings of the Report?

• Increase in Ocean Temperature:
  • Rapid Warming: The Indian Ocean's temperature has risen by 1.2°C from 1950 to 2020 and is projected to increase further by 1.7°C to 3.8°C from 2020 to 2100.
  • Marine Heatwaves: Predictions indicate an increase in marine heatwave days from an average of 20 days per year to 220–250 days per year.
    • These heatwaves are linked to quicker cyclone formation and can lead to a nearly permanent heatwave state in the tropical Indian Ocean.
    • The frequent and intense heat waves are likely to accelerate coral bleaching, destruction of seagrass, and loss of kelp forests, which are crucial to the fisheries sector.
• Changes in Heat Content of the Ocean:
  • Deep Ocean Warming: The increase in temperature extends beyond the surface down to depths of 2,000 meters, escalating the overall heat content of the ocean.
    • The heat content of the Indian Ocean is currently increasing at a rate of 4.5 zetta-joules per decade and is expected to grow at a rate of 16–22 zetta-joules per decade in the future.
  • Energy Comparison: The projected increase in heat content is likened to the energy released by one Hiroshima atomic bomb detonation every second, continuously for ten years.
• Sea-Level Rise and Thermal Expansion:
  • Increasing heat content leads to sea-level rise primarily through thermal expansion, which accounts for over half of the sea-level rise in the Indian Ocean, surpassing the effects of glacier and sea-ice melting.
• Changes in Indian Ocean Dipole (IOD) and Monsoon Patterns:
  • IOD Alterations: Due to the rise in the ocean's heat content Indian Ocean Dipole, a significant factor in determining monsoon strength, is likely to experience a 66% increase in extreme events and a 52% decrease in moderate events by the end of the 21st century.
  • Implications for Monsoons: These changes are critical as positive phases of the dipole, characterized by warmer temperatures in the western half, are favourable for the summer monsoon.
• Future Outlook:
  • Despite ongoing heatwaves, an "above-normal" monsoon is expected for June-September 2024 partially due to a positive phase of the IOD.

How do Rising Sea Levels Impact India?

• Rate of Sea Level Rise:
  • According to the Ministry of Earth Sciences, on average, the sea level along the Indian coast was observed to be rising at a rate of about 1.7 mm/year during the last century (1900-2000).
  • A 3 cm sea level rise could cause the sea to intrude inland by about 17 meters.
• India is more Susceptible:
  • India is most vulnerable to the compounding impacts of sea level rise.
  • In the Indian Ocean half of the sea level rise is due to the volume of water expanding since the ocean is warming up rapidly. The contribution from glacier melt is not as high.
  • The Indian Ocean is the fastest-warming ocean in terms of surface warming.
• Implications:
  • India is facing compound extreme events along our coastline. Cyclones are intensifying rapidly due to more moisture and heat from ocean warming.
  • The amount of flooding also increases because storm surges are compounding sea level rise decade by decade.
  • Cyclones are bringing more rain than earlier.
    • Super Cyclone Amphan (2020) caused large-scale flooding and inundated tens of km inland with saline water intruding.
  • Over time, the Indus, Ganga, and Brahmaputra rivers may shrink, and rising sea levels combined with a deep intrusion of saltwater will make large parts of their huge deltas simply uninhabitable.

What are the Ways to Tackle the Threat of Marine Heatwaves and Intensifying Cyclones?

• Mitigation Strategies:
  • Emission Reduction Strategies: Adopt and advocate for policies similar to the European Union's Emissions Trading System (ETS).
    • The ETS is a cap-and-trade scheme that incentivises industries to reduce greenhouse gas emissions, combating the root cause of marine heat waves.
  • Renewable Energy Integration: Invest in and promote renewable energy sources like Germany's transition towards solar and wind power.
    • This reduces dependence on fossil fuels and lessens the long-term impact on ocean temperatures.
• Early Warning Systems and Preparedness:
  • Advanced Monitoring: Emulate programs like Australia's Integrated Marine Observing System (IMOS).
    • IMOS utilises a network of buoys, ships, and satellites to collect real-time oceanographic data, providing crucial insights into marine heat waves heat waves and cyclone development.
  • Predictive Modeling: Leverage advancements like the National Oceanic and Atmospheric Administration's (NOAA) hurricane seasonal outlooks.
    • By statistically analysing atmospheric and oceanic data, NOAA provides forecasts for cyclone activity, allowing for better preparedness.
• Coastal Resilience Measures:
  • Mangrove Restoration: Implement initiatives like Bangladesh's efforts to restore mangrove forests.
    • Mangroves act as natural barriers, mitigating storm surges and protecting coastal communities from cyclones.
  • Infrastructure Improvements: Strive for advancements akin to the Netherlands' robust seawall network.
    • Well-maintained seawalls and levees can significantly reduce cyclone damage to coastal infrastructure and settlements.
• International Collaboration:
  • Data Sharing and Research: Foster open exchange of scientific data, similar to the Global Ocean Observing System (GOOS).
    • GOOS facilitates international collaboration in ocean observations, leading to a better understanding of marine heatwaves and cyclone development.
  • Capacity Building: Provide technical and financial assistance to developing countries, akin to the World Meteorological Organization's (WMO) Tropical Cyclone Programme.
    • This program equips vulnerable nations with resources and expertise to prepare for and respond to cyclones.