Global Dimming

Everyone has heard of global warming but much less known is global dimming.

Global dimming is the result of pollution in the atmosphere that reflects some of the suns rays, dimming and cooling the earth. The growth in global dimming and global warming have gone hand in hand since the dawn of the industrial revolution. And the effects of global dimming have masked the impact of global warming, so we have experience much less increase in world temperatures than we would have without the dimming.

Over the last 30 years we have been doing a better job of cleaning up the pollution in the atmosphere that causes the dimming. We banned CFCs in aerosols in the 1970s, and we have cleaned up smoke stack, and automotive emissions. This has been great for human health. The down side is with less global dimming, some experts are predicting much faster global warming in the coming years. If this turns out to be true we will need to accelerate our reduction of carbon emissions faster than we had planned... This will be one of the greatest challenges of the 21st Century.

For more information on global dimming check out the following links:
http://www.pbs.org/wgbh/nova/sun/
http://www.realclimate.org/index.php?p=105
http://www.documentary-film.net/search/sample.php
http://www.nasa.gov/centers/goddard/news/topstory/2007/aerosol_dimming.html

As one would expect, global climate change affects everything including parks. The National Park Conservation Association release a study on the affects of global warming on National Parks called Unnatural Disaster: http://www.npca.org/globalwarming/

Last spring I led a session on reducing your agency's carbon footprint at the National Recreation and Park Association's Environmental Summit and asked the group what impact they had seen. Officials from parks all across the United States and Canada are seeing the effects of global climate change today.