What is sea surface temperature rise? How does it affect the formation of tropical cyclones? (UPSC GS 1 2024/10 Marks)

Introduction:

Sea surface temperature rise is a significant indicator of climate change and can have various impacts on marine ecosystems and weather patterns. 

Sea Surface Temperature (SST) Rise

• SST rise refers to the increase in the temperature of the uppermost layer of the ocean, primarily due to global warming.
• Causes:
  
  • Global Warming: Increased greenhouse gas emissions trap heat in the atmosphere, leading to warming of ocean surfaces.
  • Human Activities: Pollution, deforestation, and industrial activities contribute to the overall rise in SST.

SST Rise Affects the Formation of Tropical Cyclones

• Increased Evaporation:
  
  • Warmer sea surface temperatures (SST) lead to increased evaporation of seawater.
  • This evaporation injects more moisture into the atmosphere, which is a critical component for cyclone formation.
• Enhanced Latent Heat Release:
  
  • The moisture from increased evaporation rises, cools, and condenses, releasing latent heat.
  • This release of heat fuels the cyclone, making it stronger and more intense.
• Lower Atmospheric Pressure:
  
  • The warming of the ocean causes the air above it to rise, creating a low-pressure system.
  • A tropical cyclone forms around this low-pressure area as air moves in to replace the rising warm air.
• Wind Shear Reduction:
  
  • Tropical cyclones thrive when there is low vertical wind shear (difference in wind speed and direction at different altitudes).
  • Higher SSTs can create atmospheric conditions that reduce wind shear, favoring the development of cyclones.
• Expansion of Cyclone Zones:
  
  • With rising SST, cyclones may form in regions that were previously too cool to support them.
  • This means areas further from the equator may experience more frequent tropical cyclones.
• Increased Cyclone Intensity:
  
  • Higher SSTs can result in stronger cyclones because they provide more energy (in the form of heat and moisture).
  • Example: The 2017 Atlantic hurricane season saw powerful hurricanes like Irma and Maria, which were intensified by unusually warm Atlantic waters.
• Energy Source: Tropical cyclones (hurricanes, typhoons) derive their energy from warm ocean waters. Higher SSTs provide more heat and moisture, which intensifies these storms.
• Longer Duration and Extended Range:
  
  • Cyclones can last longer and extend into regions that previously saw fewer storms, as seen with recent storms reaching higher latitudes.
  • Example: Super Typhoon Haiyan (2013), one of the strongest storms, was fueled by elevated Pacific SSTs.

Examples of SST-Induced Cyclones:

• Hurricane Katrina (2005): Warm Gulf of Mexico waters intensified the storm.
• Cyclone Amphan (2020): Warm Bay of Bengal waters contributed to rapid intensification, becoming one of the strongest storms in the region.

Conclusion:

Sea surface temperature rise is a concerning trend that is driven by human activities such as greenhouse gas emissions and deforestation. It is important to take action to reduce these impacts and mitigate the effects of climate change on marine ecosystems and weather patterns.