The understanding of the interdependence of organisms
That human decisions and activities have had a profound impact on the physical and living environment
The understanding of renewable and nonrenewable resources
The value of biodiversity
Current issues and status and looking into the future.
Links:
http://www.environmentaldefense.org/system/templates/page/issue.cfm?subnav=5 Real-time ozone monitor for 5 cities
http://www.scorecard.org/ United States Environmental map showing the scorecard for a number of environmental issues