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Natural Hazards

ERBE Observed that Mt Pinatubo Aerosols
Increased Solar Reflected Radiation

ERBE Observation Image

CERES provides global data for evaluating the radiative effects and climatic impact of natural events such as volcanic eruptions and major floods and droughts. Volcanic activity has long been suspected of causing significant short-term changes in climate. Powerful volcanic eruptions typically inject huge quantities of gases into the stratosphere, forming an aerosol layer that can remain in the atmosphere for several years. Cooling was so severe following the Tambora eruption in Indonesia that 1816 was called "the year without a summer." Cold temperatures (snow fell in August) and killing frosts in Europe and America caused extensive crop failures and famine. The 1883 eruption of Krakatoa was heard 3,000 miles away and produced sea waves almost 40 meters high. The vast stratospheric cloud caused such vivid red sunset afterglows that firemen were called out in several cities to quench the apparent conflagration. The volcanic cloud that created such spectacular atmospheric effects also acted as a solar radiation filter, lowering global temperatures as much as 1.2oC in the year after the eruption. Temperatures did not return to normal until 1888.

In 1991, a series of spectacular eruptions of Mount Pinatubo in the Philippines produced the greatest volcanic clouds observed since the beginning of the satellite era. This event presented an unprecented opportunity for an experiment in climate change. Radiative heat flow (or flux) anomalies derived from ERBE were used to determine the volcanic radiative forcing following the eruption of Mount Pinatubo. Aerosols altered the Earth's radiation balance by reflecting more of the Sun's energy back to space as indicated by the yellow and red areas in the shortwave anomaly figure on the right. The Earth continued to cool radiatively at about the same rate as before the eruption. The resulting cooling of the atmosphere and the surface depressed the mean global temperature by some 0.5-1.0oC.



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  Image: NASA Logo NASA Official: Dr. Norman Loeb
Page Curator: Edward Kizer
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