MARINE HEATWAVES



Published on 23 Feb 2025

A marine heat wave is often characterised as a region of extremely warm sea surface temperature that lasts for days to months. Marine heat waves occur when sea temperatures are higher than usual for a lengthy period of time.

Recent findings on Marine Heatwaves

  • According to IPCC Sixth Assessment Report (AR6), the sea surface temperature over the Indian ocean is likely to increase by 1 to 2 °C when there is 1.5°C to 2°C global warming.

  • The Western Indian Ocean region experienced the largest increase in marine heatwaves at a rate of about 1.5 events per decade, followed by the north Bay of Bengal at a rate of 0.5 events per decade.

  • The marine heatwaves in the Western Indian Ocean and the Bay of Bengal increased drying conditions over the central Indian subcontinent.

  • Correspondingly, there is a significant increase in the rainfall over south peninsular India in response to the heatwaves in the north Bay of Bengal.

Causes of Marine Heatwaves

  • Ocean Processes:

    • Ocean Currents: These currents can transport warm water over long distances, causing localised patches of hot water to build up.

    • Air-Sea Heat Flux: When a high-pressure system sits above a region for a long time, it traps heat in the ocean surface, preventing it from mixing with cooler water below.

    • Winds: Light winds allow warm surface water to stay stagnant, preventing it from mixing with cooler water and continuing to heat up.

  • Global Influences:

    • Climate Change: The overall warming of the Earth's atmosphere caused by greenhouse gas emissions is a major driver of marine heatwaves. The ocean absorbs a significant amount of this heat, leading to more frequent and intense marine heatwaves.

    • El Niño Southern Oscillation (ENSO): This natural climate cycle can cause changes in ocean circulation patterns that can contribute to marine heatwaves in certain regions.

Impact of Marine heatwaves

  •  Habitat Disruption: Marine heatwaves alter the physical conditions that organisms rely on, forcing them to adapt or move.

    • Example: The spiny sea urchin, unable to tolerate cooler waters in the past, has expanded its range southward due to warming seas, disrupting kelp forests it feeds on.

  • Loss of Biodiversity: Heat stress can be lethal to many marine species, impacting the variety and abundance of life in the ocean.

    • Example: Mass coral bleaching events like the one experienced by the Great Barrier Reef in 2016 are a direct consequence of marine heatwaves.

  •  Water Chemistry Changes: Marine heatwaves can exacerbate existing problems like ocean acidification and deoxygenation, creating harsher environments for marine life.

    • Example: Marine heatwaves can lead to "dead zones" where oxygen levels become too low for marine life to survive.

  •  Economic Disruptions: Heatwaves can negatively impact fisheries and aquaculture, leading to economic losses for coastal communities.

    • Example: The 2011 marine heatwave in Western Australia negatively impacted the abalone harvest, demonstrating the economic consequences of heatwaves on fisheries.

  • Ecosystem Imbalance: Marine heatwaves favour heat-tolerant species while harming others, leading to a shift in the overall balance of marine ecosystems.

    • Example: Marine heatwaves can favour the growth of jellyfish populations while harming other species like plankton, disrupting the food web and impacting the overall health of the ecosystem.

Measures to tackle marine Heatwaves

  • Global Collaboration: Expand the Indian Ocean Observing System (IOOS) and work with UNESCO's IOC to create a global marine heatwave monitoring alliance.

  • Weather Prediction Advancements: Partner with The European Centre for Medium-Range Weather Forecasts (ECMWF) to develop weather models that better integrate marine heatwave data for improved forecasting.

  • Stakeholder Engagement: Collaborate with UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) to develop educational programs on marine heatwaves for policymakers, industries, and the public.

  • Local Action: Empower local agencies to raise awareness and develop user-friendly heatwave forecast platforms.

  • Indian Initiatives:

    • Dedicated Monitoring Network: Establish a dedicated marine heatwave monitoring network within the Indian Ocean region (led by INCOIS).

    • Sustainable Fishing Practices: Implement seasonal fishing restrictions or quotas in collaboration with fisheries associations.

    • Corporate Sustainability: Incentivize sustainable practices in tourism (e.g., minimize coastal development) and aquaculture (e.g., heat-resistant techniques).

Tags:
Geography

Keywords:
MARINE HEATWAVES Recent findings on Marine Heatwaves Causes of Marine Heatwaves Impact of Marine heatwaves Measures to tackle marine Heatwaves

Syllabus:
General Studies Paper 1

Topics:
Natural Calamities and Disaster Management

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