Rising Tropical Cyclone Frequency

Context: According to a study published in the journal Nature Communications, a combination of global warming and a cyclical event called the Pacific Decadal Oscillation (PDO) could make tropical cyclones more frequent in the coming years.

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• The number of such tropical cyclones was 43% fewer in 1981-2010 compared with 1951-1980 as the PDO was in a  warmer or positive phase. 
• An El Nino is currently developing in the Pacific which has recorded rainfall deficits of 7% and 17% in central and southern India respectively.
• El Nino-Southern Oscillation (ENSO) with a positive PDO is generally not good, but when linked with a negative PDO, brings more rain to India.

Cyclone

• Cyclone: A cyclone is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above.
• Tropical cyclones are intense low-pressure areas confined to the area lying between 30° N and 30° S latitudes in the atmosphere.
• Some conditions for the emergence of a tropical cyclone are:
• Large and continuous supply of warm and moist air.
  • Strong Coriolis force that can prevent the filling of low pressure at the centre.
  • Unstable condition that creates local disturbances.
  • Absence of strong vertical wind wedge which disturbs the vertical transport of latent heat.

How Cyclones are formed

• Formation and Initial Development Stage
  • A warm sea with abundant and turbulent transfer of water vapor.
  • Atmospheric instability· 
• Mature Phase
  • Air rises and tends to spread out at the tropopause level.
  • Air warms up by compression and a warm ‘Eye’ is generated.
• Modification and Decay
  • Cyclone begins to weaken as its source of warm moist air begins to ebb, or is abruptly cut off.

Reasons for Increasing the Frequency and Intensity of Tropical Cyclone

• Climate Change: Rising sea surface temperatures provide more energy to fuel cyclones, allowing them to intensify more quickly and become more powerful. 
  • For example, cyclone Mocha over Bay of Bengal.
• Warmer Ocean Waters: As global temperatures rise, the Indian Ocean is warming, providing more heat and moisture to fuel cyclone development and intensification. 
  • For example, increasing sea surface temperature over Arabian Sea is providing ample supply of energy to intensify cyclones, for example, Cyclone Tauktae.
• Sea Level Rise: Higher Sea levels mean that storm surges can penetrate farther inland, causing more extensive coastal flooding and damage. 
  • For instance, Hurricanes are causing more intense rainfall and have increased coastal flooding.
• Changing Wind Patterns: Changes in atmospheric circulation patterns can steer cyclones towards more vulnerable areas and also contribute to their intensification.

• Ocean Heat Content: Increased heat content can result in stronger cyclones. For example, ocean heat content anomaly has led to an intensification of the Kyarr cyclone and Ockhi cyclone.
• Monsoon Variability: The Indian Ocean Dipole and El Niño-Southern Oscillation (ENSO) can affect monsoon patterns, which in turn can influence cyclone development. 

Disaster Management

• Pre-Disaster Preparation:
  • Early Warning Systems: These systems can help communities prepare and evacuate in advance, reducing the loss of lives.
  • Disaster Preparedness: Educate communities about cyclone risks, preparedness measures, and evacuation procedures along with holding regular drills.
• Response During Disaster:
  • Activation of Emergency Operations Centers.
  • Evacuation Planning and Execution: Specially for areas prone to flooding, storm surges, and landslides.
  • Search and Rescue Operations: Trained search and rescue teams, including local emergency responders, like Aapda Mitras.
• Post Disaster
  • Medical Assistance: To treat injuries, provide medical care, and prevent the outbreak of diseases.
  • Distribution of Aid: Food, water, clothing, hygiene kits, and other essential supplies are distributed to affected communities. Humanitarian agencies and NGOs also play crucial role in this stage.
  • Psychosocial Support: To help victims better deal with trauma and stress.
• Recovery and Capacity Building
  • Resilient Infrastructure: This includes constructing cyclone-resistant buildings, reinforcing critical infrastructure, etc.
  • Climate-Resilient Agriculture: Agricultural practices that can withstand heavy rainfall, waterlogging, and flooding. 
  • Community-Based Adaptation: The traditional knowledge and practices can contribute to effective resilience-building efforts.

 Conclusion

• It’s important to recognize that addressing cyclone impacts is not a one-size-fits-all approach. 
• A combination of short-term disaster response and long-term climate adaptation measures is essential for creating a more resilient future in the face of increasing cyclone intensity.

 News Source: The Hindu

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