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The explosion of the Mt. Pinatubo volcano on June 15, 1991, was the largest volcanic eruption the world had seen in nearly a century. In addition to the widespread destruction that the volcano wrought on the Philippine island of Luzon, Mt. Pinatubo's impact was felt around the world. Global average temperatures cooled for more than a year after the eruption due to the massive injection of dust and gases into the upper atmosphere.

With the 1991 Mt. Pinatubo eruption, the global effects of volcanoes on climate were captured in detail for the first time by a suite of Earth-observing satellites. The following scientists who were involved in many of these trailblazing studies are available for interviews:

A Temporary Global Cooling. Global warming was halted - at least temporarily - by the aerosol cloud from the eruption, which lowered global average temperatures by 0.5 degrees Celsius (about 1 degree Fahrenheit) through 1992.  NASA climate modelers precisely predicted this volcano-induced cooling--a powerful demonstration of the capability of these computer simulations. Contact: James Hansen, NASA Goddard Institute for Space Studies, New York, N.Y.; tel. 212-678-5500

A Global Pall of Dust and Aerosols. Pinatubo pumped so much volcanic ash and gas into the upper reaches of the atmosphere that the normal levels of stratospheric aerosols increased by more than 20 times, leading to a short-lived global cooling. Contact: Phil Russell, NASA Ames Research Center, Moffett Field, Calif.; tel. 650-604-5404;

Ozone Levels Drop Worldwide. The protective ozone layer in the upper atmosphere weakened for more than a year as the result of gases injected into the stratosphere by the eruption. NASA's TOMS instrument tracked the decline and eventual recovery from start to finish. Contact: Jay Herman, NASA Goddard Space Flight Center, Greenbelt, Md.; tel. 301-614-6039; e-mail jay.r.herman@nasa.gov

A Shift in the Weather and Winds. The eruption also caused changes in regional weather patterns. Climate models showed that Pinatubo produced a shift in wind patterns in the North Atlantic that lead to a warmer-than-usual winter in Europe in 1991-92. Contacts: Gavin Schmidt, Columbia University and NASA Goddard Institute for Space Studies, New York, N.Y.; tel. 212-678-5627; e-mail gavin.a.schmidt@nasa.gov . Drew Shindell, NASA Goddard Institute for Space Studies, New York, N.Y.; e-mail drew.shindell@duke.edu

Mudflows: A Continuing Hazard. The millions of tons of ash and rock that blanketed the flanks of Mt. Pinatubo created dangerous rivers of mud during the annual rainy season. Scientists are keeping an eye on this shifting natural hazard with airborne and space

A New View of the Swirling Atmosphere. The Mt. Pinatubo eruption was a unique natural experiment that unveiled movements in the atmosphere that scientists had never seen before. As satellites tracked volcanic aerosols moving around the globe, researchers saw movements through the troposphere into the stratosphere for the first time. Contact: Chip Trepte, NASA Langley Research Center, Hampton, Va.; tel. 757-864-5836; e-mail charles.r.trepte@nasa.gov

Visualizations of Mt. Pinatubo and several of these global climate effects will be broadcast on NASA TV on Wednesday, June 13 at 12 noon. NASA TV is broadcast on the GE2 satellite which is located on Transponder 9C, at 85 degrees West longitude, frequency 3880.0 MHz, audio 6.8 MHz.