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Peter V. Hobbs Memorial Endowed Lecture
Kane Hall Room 210


Please join the Department of Atmospheric Sciences for the
2012 Peter V. Hobbs Memorial Endowed Lecture in Experimental Meteorology

“The Anti-Greenhouse Effect Along the Spiral of Geologic Time”

Presented by
Owen Brian Toon

Professor, Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder

Tuesday, February 7, 2012, 7:30 pm Kane Hall, Room 210
University of Washington Seattle Campus


Microscopic particles in the atmosphere including desert dust, sea salt, volcanic debris, air pollution and bio-particles are found everywhere on Earth. The particles nearly counterbalance the climate changes from greenhouse gases, sometimes shut down airports, and create a substantial health risk when breathed. More severe effects have occurred in the past.

For the first half of its history, Earth may have been enveloped in an organic haze, blocking the view of the surface from space, providing a UV shield and food for the biosphere. Earth nearly froze over several times, possibly triggering the origins of complex life about 600 million years ago, perhaps due to our passage through an interstellar dust cloud. About 65 million years ago particles generated from an asteroid collision in the Yucatan Peninsula broiled the dinosaurs alive, burned most of the extant land biota then froze the rest, and so diminished sunlight reaching the surface that the food chain in the oceans collapsed. In the past 100,000 years particles from giant volcanic eruptions may have nearly eliminated our species, and more recently caused migrations and stock market collapses. The future will see more events like these and possibly worse. The smoke generated in a nuclear war could kill the majority of the people on Earth. In the near future we may be forced to moderate the climate using particles to offset rising temperatures and sea levels due to greenhouse gases. If this geo-engineering to rescue our planet isn’t needed now, it eventually will be tens or hundreds of millions of years from now as the sun swells, brightens and threatens to turn our planet into an uninhabitable cinder.

Additional information on the Hobbs Lecture can be found at http://www.atmos.washington.edu/alumni.update/Hobbs.shtml.

Time: 7:30 PM - 8:30 PM
University of Washington Seattle Campus
Kane Hall Rm. 210 (http://washington.edu/maps/?KNE)
Seattle, WA 98195

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