Global dimming
Topic: Solar Radiation, Heat Balance and Temperature · NCERT: Beyond NCERT
Meaning
Global dimming is the fall in sunlight reaching the Earth's surface. It was a few per cent between the 1950s and the 1980s. The main cause was aerosol pollution, such as sulphates. Aerosols are tiny particles floating in the air. These particles reflect sunlight. They also make clouds brighter, so the clouds reflect more light back to space. Dimming partly hid the warming caused by greenhouse gases.
Example
After about 1990, cleaner air brought "brightening" (more sunlight at the surface) to Europe and North America. Over South and East Asia, including India, dimming went on for longer because aerosol pollution stayed high.
Don't confuse with
- Global warming: global warming is the rise in average temperature caused by greenhouse gases trapping outgoing heat. Global dimming is less sunlight reaching the ground, and it works partly against warming.