Marine Heat Waves 

Syllabus: GS3/Environment

Context

• Researchers found that Marine Heat Waves (MHWs) deep in oceans may be significantly under-reported and caused by ocean currents.
  • However, they are also being impacted by global warming.

About

• In recent years, global warming has made MHWs more frequent and intense, but as per the new study this phenomenon is witnessed well beyond the surface.
• Extreme temperature changes in the temperature of the twilight zone are also a matter of concern, since many fish species and plankton reside here.
  • The twilight zone of oceans is located between 200 and 1,000 metres, still has some visibility.
  • Planktons form the base of the oceanic food chain and are a food source for small fish. 

What are Marine Heat Waves?

• It occurs when the surface temperature of a particular region of the sea rises to 3 or 4 degree Celsius above the average temperature for at least five days. MHWs can last for weeks, months or even years.
• They can occur in summer or winter – they are defined based on differences with expected temperatures for the location and time of year.

Causes of MHWs

• Climate Change: As atmospheric temperatures rise, ocean temperatures also increase, leading to more frequent and intense heat waves.
• Ocean Currents: Changes in ocean currents influence local temperatures. For example, if warm water is transported to a specific region, it can lead to elevated sea surface temperatures.
• El Niño and La Niña Events: These climate phenomena significantly alter ocean temperatures.
  • El Niño typically leads to warmer ocean conditions, which can trigger MHWs, while La Niña can have complex effects, sometimes leading to cooler temperatures in certain regions.
• Local Environmental Changes: Human activities, such as coastal development, pollution, and overfishing, alter local ecosystems and contribute to temperature increases.

Impact of Marine Heat Waves

• Deaths of Several Marine Species: MHWs along the Western Australian coast during the summer of 2010 and 2011 caused some “devastating” fish kills.
• Destruction of kelp forests: Kelps usually grow in cooler waters, providing habitat and food for many marine animals. MHWs change the ecosystem of the coast and lead to their destruction.
• Coral Bleaching: Elevated temperatures stress coral reefs, leading to bleaching and increased mortality rates.
• Species Distribution: Many marine species shift their ranges to cooler waters, affecting local ecosystems and fisheries.
• Impact on Fisheries: Altered species distributions and health affect fish populations, impacting commercial and recreational fishing.
• Economic Consequences: The fishing industry, tourism, and coastal economies suffer due to changes in fish availability and declining health of marine ecosystems.

Way Forward

• Climate Action: Reducing greenhouse gas emissions is crucial.
  • Transitioning to renewable energy sources and improving energy efficiency, can help mitigate climate change and its impacts on marine ecosystems.
• Enhanced Monitoring: Investing in ocean monitoring systems can improve our understanding of MHWs. 
• Research and Modeling: Supporting research on the causes and consequences of MHWs is vital. 
• Community Engagement: Involving local communities in conservation and management efforts can foster stewardship of marine resources. 
• Support for Vulnerable Communities: Providing assistance to communities that rely on marine resources for their livelihoods can help them adapt to changing conditions. 
• Innovative Solutions: Exploring new technologies and methods, such as aquaculture and seaweed farming, can help mitigate the impacts of MHWs while providing sustainable food sources.

Source: IE