The Supreme Court, in Mass. v. EPA, stated that the EPA must treat CO2 and other Greenhouse Gases (GHGs), as “pollutants” and then carry out an analysis to determine whether the increasing concentrations in atmospheric CO2 may reasonably be anticipated to endanger human health and welfare. The Court did not mandate regulation; rather it mandated that EPA go through an Endangerment Finding process.
EPA did so and on December 15, 2009 issued its ruling that CO2 and other GHGs must be regulated. This EPA finding and associated rulings were immediately challenged in the DC Circuit Court. The DC Circuit ruled in favor of EPA, but given the two dissents from the December 20, 2012 decision denying rehearing en banc, the matter will very likely go to the Supreme Court.
If allowed to stand, the very existence of EPA’s Endangerment Finding requires regulation that significantly increases U.S. fossil fuel and electricity prices–negatively impacting job creation as well as energy, economic and national security.
To many scientists this situation seems incredible given the ample evidence that EPA’s finding is grossly flawed. In its finding, EPA claimed with 90-99% certainty that observed warming in the latter half of the twentieth century resulted from human activity. EPA bases its finding upon Three Lines of Evidence (LoE.)