Philosophical Society of Washington

From The Chicago Heat Wave to Houston Floods

How Cities Affect Weather and Climate

J. Marshall Shepherd
NASA Deputy Project Scientist-Global Precipitation Measurement Mission

2195th Meeting Abstract
Friday, September 23, 2005 at 8:15 PM


By the year 2025, more than 60% of the world's population will live in cities, with higher percentages expected in developed nations. The urban growth rate in the United States, for example, is estimated to be 12.5%, and the recent 2000 Census found that more than 80% of the population currently lives in urban areas. Furthermore, the U.S. population is not only growing but is tending to concentrate more in urban areas within the environmentally sensitive coastal zones. Urban growth creates unique and often contentious issues for policymakers related to land use zoning, transportation planning, agricultural production, housing and development, pollution, and natural resources protection. Urban expansion and its associated urban heat islands, urban aerosol concentrations, and impervious surfaces also have measurable impacts on weather and climate processes. The devastating and deadly Heat Wave of the mid-1990s in Chicago and recent urban flooding in Houston are two manifestations of how the actual city environment can influence weather and climate processes.

This lecture will discuss various ways that cities can impact weather and climate, particularly rainfall and thunderstorms, and also address what the future implications are for weather forecasting, climate change assessment and prediction, water resource management, public health, agriculture, and urban planning. The discussion will also offer a set of recommendations for what type of studies, observations, and models are required in the future.

J. Marshall Shepherd

About the Author:

J. Marshall Shepherd received his B.S., M.S. and Ph.D in physical meteorology from Florida State University. He was the first African American to receive a Ph.D from the Florida State University Department of Meteorology, one of the nation's oldest and respected.

For the past 12 years, he has conducted research into mesoscale weather systems using aircraft, satellites, radars, and sophisticated computer models. This research seeks to understand mesoscale (i.e. thunderstorms, hurricanes, rainfall) atmospheric processes and to relate them to current weather and climate change. Dr. Shepherd's most recent work is investigating the linkage between urban cities and rainfall modification using space-based instruments. For this work, he was honored in 2004 with the Presidential Early Career Award for pioneering scientific research. He is currently serving as Deputy Mission Scientist for the Global Precipitation Measurement (GPM) mission.

He also supports mission development in NASA's Earth Science Enterprise that seeks to understand the Earth as system and how changes in the atmosphere, land, ocean, and ice regimes impact Earth's habitability, life-sustaining resources, and quality of life. Most recently, he has been an integral part of new satellite missions with the goal of understanding the global energy and water cycle and its roles in weather and climate change.

Dr. Shepherd provides service to NASA and the larger scientific and educational communities through his work as a National Science Foundation advisory council member, United Nation's World Meteorological Organization steering committee member, and authorship on the Inter-governmental Panel on Climate Change (IPCC) report. He also recently co-authored a children's book on conducting weather-related science projects and understanding basic weather information.

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