"PERC - Property and Environment Research Center is the nation's oldest and largest institute dedicated to original research that brings market principles to resolving environmental problems...PERC pioneered the approach known as free market environmentalism, which is based on the following tenets. Private property rights encourage stewardship of resources. Government subsidies often degrade the environment. Market incentives spur individuals to conserve resources and protect environmental quality. Polluters should be liable for the harm they cause others."
(http://www.perc.org/aboutperc/index.php?s=1)