Peter V. Hobbs Memorial Endowed Lecture in Experimental Meteorology
Professor O. Brian Toon
February 7, 2012
7:30-8:30, Kane Hall, Room 210
Dr. Owen Brian Toon
Professor, Department of Atmospheric and Oceanic Sciences, University of Colorado
Lecture: "The Anti-Greenhouse Effect Along the Spiral of Geologic Time"
Abstract
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.
Did Earth look like Titan for half of Geologic time? |
Could we all starve after a nuclear war? |
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About the Speaker
Dr. Toon is a director and professor in the Department of Atmospheric and Oceanic Sciences and a fellow at the Laboratory for Atmospheric and Space Physics at the University of Colorado. Currently, Dr. Toon is active in the following research areas: theoretical studies of stratospheric volcanic clouds and aerosols and of polar stratospheric clouds; theoretical studies of cirrus, stratus and cumulus clouds, and of direct and indirect effects of aerosols on climate; experimental investigations of stratospheric ozone loss, cirrus, stratus and stratospheric clouds, indirect effects of aerosols on clouds; and theoretical investigations of planetary atmospheres, with the goal of understanding the clouds and climates of the terrestrial planets. His research on the asteroid impact that killed the dinosaurs led to the discovery of nuclear winter due to the major decrease in temperature. He is a fellow of the American Meteorological Society and the American Geophysical Union.
Peter V. Hobbs Memorial Endowed Lecture in Experimental Meteorology
Professor Greg McFarquhar
May 21, 2010
3:30-4:50, Johnson Hall, Room 075
Dr. Greg M. McFarquhar
Professor, Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign
Lecture: "Use of In-situ Observations to Examine Aerosol Impacts on Mixed-Phase Arctic Clouds, Radiation and Climate"
Abstract
Comprehensive data on arctic boundary layer aerosol and cloud microphysical and radiative properties were collected during the 2004 Mixed-Phase Arctic Cloud Experiment (M-PACE) and the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC). During M-PACE, data from in-situ microphysical sensors were collected that characterize how cloud particle shape, size, phase and bulk properties varied with height. A much more comprehensive dataset was obtained during ISDAC, in which an unprecedented suite of 42 cloud and aerosol instruments was employed to study the influence of aerosols on clouds affected by ice. In-situ data obtained during ISDAC above, below, and within single-layer stratus are leading to a process-oriented understanding of how aerosols affect the microphysical and radiative properties of arctic clouds. Ultimately these data will be used to improve the representation of cloud and aerosol processes in models covering a variety of spatial andd temporal scales, and to determine the extent to which long-term surface-based measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating in the Arctic.
About the Speaker
Dr. McFarquhar is a leading authority on Cloud Physics, especially the physics of ice particles in clouds. In the tradition of Peter Hobbs, McFarquhar has led many field experiments using aircraft to make detailed measurements in clouds. His scholarship and teaching have been honored by the University of Illinois and the Canadian Meteorological and Oceanographic Society.
Peter V. Hobbs Memorial Endowed Lecture in Experimental Meteorology
Sir Keith A. Browning
Friday, October 24, 2008
Inaugural Lecture
Dr. Keith A. Browning
FRS, Emeritus Professor, University of Reading
Lecture: "Origins of the Most Damaging Winds in Extra-Tropical Cyclones"
About the Speaker
Dr. Browning served as the Director of Research in the UK Met Office. He is a Fellow of the American Meteorological Society, receiving the Rossby Medal in 2003, Past President of the Royal Meteorological Society, receiving the Symons Gold Medal in 2001, and a Fellow of the Royal Society. His work with Frank Ludlam on the supercell thunderstorm at Wokingham, UK in 1962 was the first detailed study of such a storm. His research covered many areas of mesoscale meteorology including developing the theory of the Sting jet.
Post-Lecture Reception
Inaugural reception on October 24, 2008, at Kane Hall.
Stephen Hobbs (left), Ann and Keith Browning, Sylvia Hobbs (right).
Photo: D. Hartmann