Today’s decision of the U.S. Supreme Court permitting the EPA (Environmental Protection Agency) to regulate greenhouse gas emissions relies constitutionally upon subscription to the statement ‘Greenhouse gases are pollutants.’

But are they? Is carbon dioxide an air pollutant? To define carbon dioxide as an air pollutant certainly provides a nice way to regulate vehicle emissions – which is the reason for the decision. But are we polluting when we breathe, for example? The claim that we are wouldn’t be too far outside of the left-wing worldview, who tend to see the majority of human activity as inherently evil or degraded or out of step with ‘nature’ in some way.