Tonga Volcanic Eruption – UPSC Prelims

  • A massive underwater volcanic eruption occurred in Tonga in the Southern Pacific Ocean.
  • This has raised questions whether this volcanic eruption could cool the climate.
  • How does volcanic eruption cool the climate?
    • Volcanic Eruption releases several types of gases, steam and ash into the stratosphere.
    • One of the gases it releases include sulphur dioxide (SO2) which is of particular interest because of its global cooling effect.
    • This is because Sulphur dioxide from volcanic eruptions turns into sulphuric acid, which condenses rapidly in the stratosphere to form fine sulphate aerosols.
    • The aerosols increase the reflection of radiation from the sun back into space, making it harder for the sun’s energy to reach the Earth’s surface, which cools the climate.
  • Will Tonga Volcanic Eruption cool the climate?
    • In 1991, Mount Pinatubo volcanic explosion occurred in the Philippines. Pinatubo released about 15 million tonnes of sulphur dioxide into the stratosphere. The total mass of SO2 in the volcanic cloud was 20 Tg.
    • Due to this explosion, researchers recorded a 0.5 degrees Celsius (°C) drop in the average global temperature over large parts of the earth between 1992 and 1993.
    • On the other hand, the Tonga volcanic cloud contains roughly 0.4 teragram (Tg) of SO2. This means that the (Tonga) event appears unlikely to have a significant cooling effect on temperatures globally.
    • However, experts said it was still too early to draw conclusions as new data would emerge. Also, more eruptions were possible.
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