Climate Change Ecological Society of America 02.01.01 Over the past 220,000 years (for which we have records from ice cores of the polar ice caps), glacial and interglacial periods have come and gone as the concentration of atmospheric carbon dioxide has risen and fallen. Changes in the average air temperature have been in direct response to the heat-trapping influence of carbon dioxide (see figure at right).     Why is there concern now for increases in atmospheric carbon dioxide and temperature that have been observed on Earth before?     There are two reasons. The first is that the current rise in atmospheric carbon dioxide is due to human activities, mostly the burning of fossil fuels. The second is the rapid rate of carbon dioxide increase, 30% since the beginning of the Industrial Revolution less than 200 years ago. Such an increase has not been experienced before on Earth in all of human history or during the evolution of our current ecosystems. If the past is any indication of the future, we are in for significant global warming. CLICK HERE for more information! Prepared by the Ecology Society of America   1707 H St., NW   Suite 400   Washington, DC 20006 ©2001 The Aurora Collection, Inc. All Rights Reserved. Site Development by: Interactive Multimedia. Inc.