Imagine the Earth as a beach ball one metre in diameter, with a skin one millimetre thick. The entire biosphere - the surface of the Earth and all life on the planet, would be only as thick as the beach balls' plastic skin. Earth is able to support life because of its fragile but protective atmosphere. Without the atmosphere, the Earth's average temperature would be minus 18 degrees Celsius, too cold to sustain life. Brown smog, known as Arctic Haze, is found over the High Artic, far away from the actual source.
Human activities have the potential to affect our fragile environment.
Volcanoes and volcanic eruptions may affect climate. Some of the dust and particles even reach the stratosphere. These particles reflect some of the incoming sunlight and have a temporary cooling effect. Generally, the effect is short term, lasting for little more than a year. However, the impact from large eruptions like that of Mount Pinatubo in the Philippines in 1991 may last for two to three years.