Marine Heatwaves

Marine Heatwaves

News: 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.

What is Marine Heatwaves?
• Marine heatwaves are periods of abnormally high ocean temperatures relative to the average seasonal temperature in a particular marine region. They can last for weeks, months or years, and affect large areas of the ocean or small patches of coastline.
• Marine heatwaves are caused by a variety of factors, such as weather patterns, ocean currents, climate variability and climate change.

How does Marine Heatwaves impact rainfall in North-Western India?
• The marine heatwave in the Bay of Bengal increased sea surface temperatures, causing higher evaporation rates and a greater moisture supply in the atmosphere. This surplus of moisture contributed to above-average rainfall in northwest India.
• The marine heatwave, along with changing timescales of depressions, affected the path and trajectory of these weather systems. Depressions tended to move more towards northwest India rather than northcentral India, causing a higher concentration of rainfall in the northwest region, leading to above-average rainfall in that area.

What are the impacts of Marine Heatwaves?

Impacts
• Habitat Destruction - Example - Spiny sea urchin off S-E Australia.
• Widespread Coral Bleaching
• Impact on productivity and profitability of Fisheries and aquaculture
• Changes in ocean ecosystem Make Extreme weather events more likely
• Loss of Biodiversity