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About The Marine Heatwave


The northern Bay of Bengal has been experiencing an intense Marine Heatwave since 28th June 2023, leading to India’s usually arid northwest receiving extreme rainfall.


GS I: Geography

Dimensions of the Article:

  1. Marine Heatwave
  2. Impact of Marine Heatwave on Rainfall in Northwest India
  3. Impacts of Marine Heatwaves

Marine Heatwave:

  • Marine heatwaves are prolonged periods of abnormally high Sea Surface Temperature (SST).
  • These events can lead to coral bleaching, seagrass destruction, and loss of kelp forests, impacting the fisheries sector negatively.
  • Common drivers of marine heatwaves include ocean currents that accumulate warm water and air-sea heat flux, which is warming from the atmosphere through the ocean surface.
  • Winds can amplify or dampen the warming effects of a marine heatwave, and climate modes like El Niño can influence the occurrence of these events in specific regions.

Impact of Marine Heatwave on Rainfall in Northwest India:

  • The marine heatwave in the Bay of Bengal elevated sea surface temperatures, resulting in increased evaporation rates and a higher supply of moisture in the atmosphere.
  • This surplus moisture contributed to above-average rainfall in northwest India.
  • The marine heatwave likely influenced the formation and behavior of low-pressure systems called depressions in the Bay of Bengal.
  • These depressions play a significant role in monsoon and rainfall patterns.
  • The marine heatwave, along with changing timescales of depressions, affected the path and trajectory of these weather systems.
  • Depressions were more inclined to move towards northwest India rather than north-central India, leading to a concentration of rainfall in the northwest region and resulting in above-average rainfall in that area.

Impacts of Marine Heatwaves:

  • Ecosystem Structure: Marine heatwaves can alter ecosystem structure by favoring certain species while suppressing others.
  • Mass Mortality: Marine heatwaves have been associated with mass mortality events in marine invertebrates, leading to significant ecological disruptions.
  • Behavioral Changes: Species may be forced to change their behavior in response to marine heatwaves, putting them at increased risk of harm.
  • Habitat Range Shifts: Marine heatwaves can cause shifts in the habitat ranges of species, resulting in changes to ecosystem dynamics. For example, the expansion of spiny sea urchins into new areas can negatively impact kelp forests.
  • Economic Losses: Marine heatwaves can have significant economic impacts, particularly on fisheries and aquaculture industries.
  • Biodiversity Loss: Marine heatwaves can lead to drastic declines in biodiversity, affecting the overall health and functioning of marine ecosystems.
  • Corals and Bleaching: Marine heatwaves can cause widespread coral bleaching, leading to coral mortality and ecosystem degradation.
  • Interaction with Other Stressors: Marine heatwaves often occur alongside other stressors such as ocean acidification, deoxygenation, and overfishing. These combined stressors can further damage habitats and increase the risks of deoxygenation and acidification in affected areas.

-Source: Down To Earth


July 2024