Global dimming facts for kids
Global dimming is when the amount of sunlight reaching Earth's surface slowly gets less. It means less energy from the sun reaches us. One main reason for global dimming is pollution. It changes the water cycle by making less water evaporate and causing less rain in some places. Global dimming can also make Earth cooler. This cooling might hide some of the warming caused by greenhouse gases from global warming.
What Causes It and What Happens?
Tiny bits of air pollution can soak up the sun's energy or bounce sunlight back into space. These tiny pollution particles can also become the center for cloud droplets to form around. When there are more pollution particles, clouds end up with many more smaller water droplets. These smaller droplets make the clouds reflect more light. This means more sunlight bounces back into space, and less light reaches Earth's surface.
Clouds also affect how much heat stays on Earth or escapes into space. This process is tricky and changes depending on the time of day, where you are, and how high up the clouds are. During the day, clouds can block sunlight from coming in. This helps to cool down the Earth. At night, clouds can trap heat on Earth, slowing down how quickly it escapes.
Even volcanic ash can stop sunlight from reaching Earth. We've seen Earth's temperatures drop after big volcanic eruptions. Some examples include the eruptions of Mount Agung in 1963, El Chichon in 1983, Ruiz in 1985, and Mount Pinatubo in 1991. However, even after huge eruptions, ash clouds don't stay in the air for a very long time.
How It Affects the Water Cycle
Global dimming is affecting Earth's water cycle. It can reduce the amount of rain, which is super important for getting fresh water. In 2001, scientists at the Scripps Institution of Oceanography studied this. Their research suggested that pollution has a bad effect on the water cycle.
Another example of global dimming happened in 2006 in the northern hemisphere during hurricane season. A NASA study found that big dust storms from the Sahara Desert in June and July blew dust over the Atlantic Ocean. This dust formed a cover over the ocean, making it cooler. This cooling then reduced how many hurricanes could form and grow.
Images for kids
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NASA photo showing airplane contrails and natural clouds. After the September 11, 2001 attacks, planes were grounded in North America. The temporary disappearance of contrails showed how these thin ice clouds affect Earth's surface temperatures.
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Sun-blocking aerosols around the world steadily declined (red line) since the 1991 eruption of Mount Pinatubo, according to satellite estimates. Credit: Michael Mishchenko, NASA
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This picture shows how well a climate model (a computer program that predicts climate) matches past temperatures. The "sulfate" part, which is negative, is linked to the tiny pollution particles that cause global dimming.
See also
In Spanish: Oscurecimiento global para niños
