Volcanism and climate
Topic: Climate Change: Causes, Evidence and the Global Response · NCERT: Class 11, Ch 11 "World Climate and Climate Change"
Meaning
Large volcanic eruptions can cool the Earth for a few years. They blast sulphur dioxide high into the stratosphere, the calm upper layer of the atmosphere. There it forms tiny sulphate droplets that reflect sunlight back to space. Less sunlight reaches the ground, so temperatures drop. The effect fades as the droplets fall out of the sky.
Example
Mount Pinatubo in the Philippines erupted in 1991 and cooled the globe by about 0.5 °C. El Chichón in Mexico (1982) also had a cooling effect. Class 11 spells these "Pinatoba" and "El Cion". Earlier, Tambora in Indonesia (1815) caused the "year without a summer" in 1816.
Don't confuse with
- Volcanic CO2 and global warming: volcanoes do release CO2, but well under 1% as much as humans. So volcanoes cannot explain the long-term warming of today. Their main effect on climate is short-term cooling.