Why in the news?

  • Warm-water coral reefs have been identified as the world’s first climate tipping point, according to the Global Tipping Points Report 2025.

Corals

  • What is it?:
    • Corals are calcareous rocks, formed from the skeletons of minute sea animals, called polyps.
    • The polyps extract calcium salts from seawater to form hard skeletons which protect their soft bodies.
    • The corals live in colonies fastened to the rocky seafloor.
    • Corals are examples of symbiotic relations which live with algae called zooxanthellae.
  • Conditions for Growth of Corals:
    • Corals thrive in tropical waters-between 30°N and 30°S latitudes.
    • The ideal depths for coral growth are 45 m to 55 m below sea surface, where there is abundant sunlight available.
    • The temperature of water should be around 20°C.
    • Clear salt water is suitable for coral growth.
    • Adequate supply of oxygen and microscopic marine food, called plankton, is essential for growth and existence.
  • Reasons for Degradations of Corals:
    • Ocean Warming: Causes coral bleaching by expelling symbiotic algae.
    • Ocean Acidification: Weakens coral skeletons due to lower pH.
    • Coastal Pollution: Sewage, agricultural runoff, and sediments smother corals.
    • Overfishing: Disrupts reef food chains and ecological balance.
    • Coral Mining: Extraction for construction and lime destroys habitats.
    • Tourism Pressure: Anchoring, trampling, and waste degrading reefs.
    • Marine Debris: Plastic and nets entangle and suffocate corals.
    • Diseases: Microbial and fungal infections increase with stress.
    • Climate-Induced Storms: Cyclones and hurricanes physically break coral structures.

Tipping Point

  • Definition: A climate tipping point refers to a threshold beyond which a small change in global temperature can trigger a self-reinforcing and potentially irreversible shift in a natural system.
  • In the Context of Corals:
    • For coral reefs, this threshold is estimated to lie between 1°C and 1.5°C of warming.
    • Once exceeded, reefs can rapidly degrade, leading to bleaching, coral death, and transformation into algae-dominated ecosystems.