
AMS Summer Policy Colloquium - Media session (SPC)
06/21/08 • 228 min
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Solar Radiation, Cosmic Rays and Greenhouse Gases: What's Driving Global Warming? (23 March 2008)
Separating Solar and Anthropogenic (Greenhouse Gas-Related) Climate Impacts During the past three decades a suite of space-based instruments has monitored the Sun’s brightness as well as the Earth’s surface and atmospheric temperatures. These datasets enable the separation of climate’s responses to solar activity from other sources of climate variability (anthropogenic greenhouse gases, El Niño Southern Oscillation, volcanic aerosols). The empirical evidence indicates that the solar irradiance 11-year cycle increase of 0.1% produces a global surface temperature increase of about 0.1 K with larger increases at higher altitudes. Historical solar brightness changes are estimated by modeling the contemporary irradiance changes in terms of their solar magnetic sources (dark sunspots and bright faculae) in conjunction with simulated long-term evolution of solar magnetism. In this way, the solar irradiance increase since the seventeenth century Maunder Minimum is estimated to be slightly larger than the increase in recent solar activity cycles, and smaller than early estimates that were based on variations in Sun-like stars and cosmogenic isotopes. Ongoing studies are beginning to decipher the empirical Sun- climate connections as a combination of responses to direct solar heating of the surface and lower atmosphere, and indirect heating via solar UV irradiance impacts on the ozone layer and middle atmosphere, with subsequent communication to the surface and climate. The associated physical pathways appear to involve the modulation of existing dynamical and circulation atmosphere-ocean couplings, including the El Nino Southern Oscillation (El Nino/La Nina cycles) and the Quasi-Biennial Oscillation. The Sun's Role in Past, Current and Future Climate Change Correlations of instrumental or reconstructed climate time series with indices of solar activity are often being used to suggest that the climate system is tightly coupled to the sun. Yet correlations have to be used with caution because they are not necessarily synonymous with cause-and-effect relationships. Therefore, it is critical to understand the physical mechanisms that are responsible for the signals. Independent tests can then be applied to validate or reject a hypothesized link. Spatial structures that are related to the processes that translate the solar influence into a climatic response can serve as such a test. A particularly powerful example is obtained by looking at the vertical extent of the solar signal in the atmosphere. Biographies Dr. Judith Lean is Senior Scientist for Sun-Earth System Research in the Space Science Division of the Naval Research Laboratory in Washington, DC. She has served on a variety of NASA, NSF, NOAA and NRC advisory committees, including as Chair of the National Research Council (NRC) Working Group on Solar Influences on Global Change and, most recently, the NRC Committee on a Strategy to Mitigate the Impact of Sensor De-scopes and De-manifests on the NPOESS and GOES-R Spacecraft. A member of the AGU, IAGA, AAS/SPD and AMS, she was inducted as a Fellow of the American Geophysical Union in 2002 and a member of US National Academy of Sciences in 2003. Dr. Caspar Ammann is a research scientist, in the Climate and Global Dynamics Division of the National Center for Atmospheric Research in Boulder, Colorado. He has a M.S. degree in Geography and Geology from the University of Bern, Switzerland and a Ph.D. in Geosciences from the University of Massachusetts. His primary research is focused on the climate of past centuries and millennia, and how the current changes compare to this natural background. He has reconstructed past climates as well as volcanic forcing from proxy (e.g., ice cores, corals etc..) records and then simulated climate variability and response to forcings in state-of-the-art coupled Atmosphere-Ocean-General Circulation Models.
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Coping with Climate Change: Gulf Coast Transportation and New York City Waterworks
Gulf Coast Transportation: Coping with the Future Climate affects the design, construction, safety, operations, and maintenance of transportation infrastructure and systems. The prospect of a changing climate raises critical questions regarding how alterations in temperature, precipitation, storm events, and other aspects of the climate could affect the nation’s roads, airports, rail, transit systems, pipelines, ports, and waterways in the region of the U.S. central Gulf Coast between Galveston, Texas and Mobile, Alabama. This region contains multimodal transportation infrastructure that is critical to regional and national transportation services. More broadly, what happens in the Gulf region will no doubt, have ripple effects nationwide and internationally, as was evident in the aftermath of hurricane Katrina. New York City: Preparing for Climate Change New York City (NYC) represents one of the first substantial efforts to undertake climate-change planning for infrastructure changes in a large urban area. Notable characteristics of the NYC system are that it is a mature infrastructure system, that its managers are skilled at dealing with existing hydrologic variability, and that there are many potential adaptations to the risk of climate change in the NYC water supply, sewer, and wastewater treatment systems. Capitalizing on this expertise and experience, the work of the Climate Change Task Force of the NYC Department of Environmental Protection, has focused on the water supply, sewer, and wastewater treatment systems of NYC. Biographies Michael J. Savonis has 25 years of experience in transportation policy, with extensive expertise in air quality and emerging environmental issues. He has served as Air Quality Team Leader at the Federal Highway Administration (FHWA), since 1996. For the past 16 years, Mr. Savonis has overseen the Congestion Mitigation and Air Quality Improvement Program which invests more than $1.5 billion annually to improve air quality. He directs FHWA’s transportation / air quality policy development, research program, and public education. He received DOT’s Silver Medal in 1997 and FHWA’s Superior Achievement Award in 2004. Dr. Cynthia Rosenzweig is a Senior Research Scientist at the Goddard Institute for Space Studies at Columbia University. Her primary research involves the development of interdisciplinary methodologies by which to assess the potential impacts of and adaptations to global environmental change. She has joined impact models with global and regional climate models to predict future outcomes of both land-based and urban systems under altered climate conditions. Advances include the development of climate change scenarios for impact and adaptation analysis, and the application of impact models at relevant spatial and temporal scales for regional and national assessments. Recognizing that the complex interactions engendered by global environmental change can best be understood by coordinated teams of experts, Dr. Rosenzweig has organized and led large-scale interdisciplinary, national, and international studies of climate change impacts and adaptation. She co-led the Metropolitan East Coast Regional Assessment of the U.S. National Assessment of the Potential Consequences of Climate Variability and Change, sponsored by the U.S. Global Change Research Program, and was the lead scientist on the New York City Department of Environmental Protection Climate Change Task Force.
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