Air Quality: The air we breathe is cleaner. Between 1970 and 2005, total emissions of the six principle air pollutants in the United States (nitrogen dioxide, ozone, sulfur dioxide, particulate matter, carbon monoxide and lead) tracked by the Environmental Protection Agency declined by 53 percent.1 During this same time period, the U.S. gross domestic product increased 195 percent, vehicle miles traveled increased 178 percent, energy consumption increased 48 percent and the U.S. population increased 42 percent.2
Forests: The U.S. is gaining forestland. The United States averaged an annual gain in net forest area of 159,000 hectares per year between 2000 and 2005. The U.S. is the fourth leading nation in the world with respect to annual net gain in forest area.3 Globally, the annual net loss of forests has decreased from an average of 8.9 million hectares per year during the time period of 1990-2000 to 7.3 million hectares per year between 2000 and 2005.4
Soil Erosion: Soil erosion rates are falling. Estimated soil erosion rates in the U.S. decreased by 43 percent between 1982 and 2003. In 2003, 72 percent of all cropland was eroding at or below what the U.S. Department of Agriculture's Natural Resources Conservation Service considers a tolerable level, compared to only 60 percent of cropland meeting this standard in 1982.5
Wetlands: The U.S. is gaining wetlands. Between 1998 and 2004, the U.S. experienced a net gain of 191,750 acres of wetlands, which is equal to an average net gain of 32,000 acres of wetlands per year.6 There are an estimated 107.7 million acres of wetlands in the conterminous United States.7
Prepared by Peyton Knight
1 U.S. Environmental Protection Agency, "Air Emissions Trends - Continued Progress Through 2005," available at http://www.epa.gov/air/airtrends/econ-emissions.html as of April 17, 2007.
3 Food and Agriculture Organization of the United Nations, "Global Forest Resources Assessment 2005," Chapter 2, p. 21, available at http://www.fao.org/docrep/008/a0400e/a0400e00.htm as of April 17, 2007.
4 Ibid, p. 13.
5 U.S. Department of Agriculture Natural Resources Conservation Service, "Natural Resources Inventory 2003 Annual NRI," available at http://www.nrcs.usda.gov/Technical/land/nri03/nri03eros-mrb.html as of April 17, 2007.
6 U.S. Fish and Wildlife Service, "Status and Trends of Wetlands in the Conterminous United States 1998 to 2004," p. 15, available at http://wetlandsfws.er.usgs.gov/status_trends/national_reports/trends_2005_report.pdf as of April 17, 2007.
7 Ibid, p. 16.