Don't have the source to hand, unfortunately, but I read somewhere that the actual environmental benefits of the whole world going into lockdown have been pretty minimal, the reason being that the amount of harm done by multinational corporations dwarfs the amount done even by all of us together as individuals - i.e. unless action is taken to regulate the fossil fuel industry and the corporate world, nothing we do as individuals is going to make that big a difference (which obviously doesn't mean we shouldn't do it, but is a measure of how fucked we are).