Scientific Colloquium
February 4, 2005

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 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.