You've all heard of global warming but global dimming has gotten less attention - because it can be confusing that cooling would be bad when warming is bad.
Global dimming is when fossil fuel burning doesn't just release the gases that traps the sun's heat within our atmosphere but also emits particulate pollution, composed primarily of sulphur dioxide, soot and ash. In the atmosphere, those particulates absorb solar energy and reflect sunlight back into space.
That's good, right? Not really, because particulate pollution changes the properties of clouds so they are more reflective and produce less rainfall. The reduction in heat reaching the Earth's surface as a result of both of these processes is what has begun to be called global dimming.
At a time when fossil fuel use was high and so was particulate pollution, Earth had a 4% reduction in radiation from the Sun. But once stricter pollution controls kicked in, there is now more radiation let in and the temperature has risen since 1990.
