But they did not authorize the way that the EPA was setting standards for gas-fired power plants. The technicalities here run deep, but the fact that some academics at Yale think that it should be allowed tells us nothing -- already, three of the most brilliant legal minds in the country have already publicly dissented from the Supreme Court's opinion on the subject.
In the face of the ambiguity, the bias should be for the legislature to act to correct the ambiguity. There is no constitutional issue at stake, just a question of what the act authorized. Congress can just deal with this.
EDIT: This is incorrect; as pointed out below, the 1970 Act did not mention greenhouse gases or CO2 specifically. As of the 2022 amendment to the act there are several explict areas where greenhouse gases are specifically mentioned.