2. What did the petitioners, including the State of Massachusetts, want the EPA to do?
3. The EPA said that, even if it had the authority to regulate greenhouse gas emissions from motor vehicles, it would not do so. What reasons did the EPA give for this refusal? What did the Supreme Court say about those reasons?
4. Following this decision of the Supreme Court, what was the EPA required to do? Was the EPA required to set a standard for greenhouse gas emissions from new vehicles?
5. Look back at the discussion about proving causation at the start of Part Two of this chapter. Did the Supreme Court say that greenhouse gas emissions from vehicles caused global warming? What did the Court observe about causation?
A well-documented rise in global temperatures has coincided with a significant increase in the concentration of carbon dioxide in the atmosphere. Respected scientists believe the two trends are related. For when carbon dioxide is released into the atmosphere, it acts like the ceiling of a greenhouse, trapping solar energy and retarding the escape of reflected heat. It is therefore a species—the most important species—of a “greenhouse gas.”