When Joseph R. Biden, Jr. is inaugurated as the 46th President of the United States on January 20, he will reverse many of the environmental actions taken by President Donald Trump. Some of this he can and probably will do immediately, possibly on Inauguration Day; other actions will have to go through administrative processes that will take several months, at least. The Trump Administration neither secured nor repealed almost any environmental legislation even while Republicans controlled both the House and the Senate, and little it did in this area is irrevocable.