Amplifiers: Aerosols
Small particles in the air (aerosols) may have warming or cooling effects, depending on their characteristics. Sulfate (SO4) aerosol, for example, is light-colored and reflects sunlight back into space. The cooling effect of volcanic aerosols from the Mt. Tambora eruption of 1815 caused North America’s “year without a summer” in 1816. Sulfate aerosol is also produced by fossil fuel burning.
Black soot, which is a familiar component of urban smog and smoke from wild fires, has the opposite effect. The dark particles absorb the Sun’s energy in much the same way that dark asphalt roads become warm on sunny days.
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Aerosols Can Have Different Effects
Different types of small particles can have either warming or cooling effects. Sulfate aerosols released by volcanoes reflect sunlight and cool the Earth. Black soot released by smoke stacks and wild fires absorbs solar radiation and can warm the Earth. (Photo of Redoubt Volcano courtesy of USGS DDS-39) |
Aerosol concentrations change for many reasons, including volcanic eruptions, spread of fires, increased windiness, drying of damp soils, changes in industrial processes, and more. Accurately projecting the extent and effect of aerosols is one of the major challenges in modeling the future of climate change.
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