Type: Prelims Only

Why in the News?

A 24-year-long study conducted by the Nature Conservation Foundation reveals that coral cover in Lakshadweep has declined by 50% since 1998.

Coral Decline in Lakshadweep: Key Highlights

• Study Duration: Based on a 24-year study (1998–2022).
• Findings: 50% decline in live coral cover—from 37.2% to 19.6%.
• Main Cause: Repeated marine heatwaves linked to climate change.
• Study Locations: Monitored across Agatti, Kadmat, and Kavaratti atolls.
• Response Clusters: Six coral groups identified based on:
  • Depth and wave exposure
  • Heat resistance and recovery patterns
• Recovery Timeline: Requires at least 6 years without bleaching for healthy regeneration.

Back2Basics: Corals and Coral Bleaching:

• About: Corals are colonies of tiny animals called polyps, which build calcium carbonate skeletons.
• Symbiotic Algae: Host zooxanthellae, microscopic algae that provide nutrients via photosynthesis.

• Coral Types:

• • Hard Corals: Form reef structures (e.g., brain coral, staghorn coral).
  • Soft Corals: Flexible, grow on reef surfaces but do not build reefs.
• Habitat Requirements:
  • Water Quality: Must be clean and low in sediment.
  • Temperature Range: Prefer 20–21°C.
  • Depth: Typically found in waters less than 90 metres deep.
  • Salinity: Optimal range is 27–30 parts per thousand (ppt).
  • Ocean Currents: Require nutrient-rich water flow.
• Coral Bleaching:
  • Cause: Triggered by heat stress, pollution, or acidification, which drive algae out.
  • Effect: Coral turns white due to loss of algae; Loses its main food source. Dies if stress persists for long periods.

Why in the News?

The World Bank’s report, “Towards Resilient and Prosperous Cities in India”, warns that climate risks like extreme heat and floods threaten India’s cities, despite their role as economic growth engines.

About the ‘Towards Resilient and Prosperous Cities in India’ Report

• Prepared By: World Bank in collaboration with the Ministry of Housing and Urban Affairs
• Focus: Evaluates Indian cities’ exposure to climate risks like heatwaves and urban flooding
• Scope: Covers 24 cities with deeper analysis of Chennai, Indore, New Delhi, Lucknow, Surat, and Thiruvananthapuram
• Support: Backed by Global Facility for Disaster Reduction and Recovery (GFDRR)

Key Highlights:

• Urban Growth:

• • 70% of new jobs to emerge in urban areas by 2030
  • Urban population to nearly double to 951 million by 2050
  • Estimated housing demand: 144 million new homes by 2070

• Climate Vulnerabilities:

• • Urban heat: City temperatures rising by 3–4°C due to the heat island effect
  • Flood risk: Rapid construction limiting natural drainage and stormwater absorption

• Investment Needs: $2.4 trillion required by 2050 for low-carbon, climate-resilient infrastructure

• Recommendations:

• • Promote cool roofs, urban green spaces, and early warning systems
  • Invest in energy-efficient housing, flood-resilient transport, and waste systems
  • Strengthen urban financial systems and incentivize private participation