The final presidential debate on Thursday crystallized stark differences between the candidates on climate and energy policy, as Joseph R. Biden Jr. stressed the urgency of addressing climate change while President Trump warned that the Democratic nominee’s plans would hurt the economy.

Oil and gas production in select basins

Calling climate change “an existential threat to humanity,” Biden said, “We have a moral obligation to do something,” and that he would seek to transition away from oil and gas toward renewable energy. The former vice president also said he would end federal subsidies for the oil industry.

Trump, meanwhile, said Biden’s $2 trillion climate plan would be “an economic disaster,” and seized on Biden’s comments to warn oil-producing states about the potential impacts of regime...