Use his/her face to save the world, via network television.
First you will become a producer of network television shows, a task that should take approximately 14 months to two years. Thus, you will be the sort of powerful person whose phone calls are never refused, even by those who have told you to never ever call again.
(Your position of power will have afforded you a staff of office workers, including a secretery, perhaps two(!), who will place your phone calls for you, including those calls to those who have told you to never ever call again, allowing the phone call to be placed without really disobeying anybody, technically.)
And as a producer of network television shows, a very successful one at that, you will one day, 42 months to 4 years from now, say to the people who own the television network that you will produce a television show that will save the world.
When they ask you for a plot summary, you will explain to them that the show will amount to a single televised image of a face and anyone or anything that sees this face, even trees, will count as a section of the world that has been saved.
And inevitably, of course, since people cannot come to own television networks without asking important questions, the people who own the television network will ask you what sort of face you are planning to televise. And, with a flourish, you will pull from your briefcase a photograph of his/her face and hold it up before the people who own the television network. And the people who own the television network will look upon the photograph and the people who own the television network and the table and the walls and windows will, together, as one section of the world, have been saved and the television show will be greenlighted.
Soon after the debut of the television show, which will be called "Just Look At The Face!", headlines will appear atop newspapers declaring "World Saved!" and a photograph of his/her face will be displayed there in the body of the articles, thereby saving other parts of the world, those parts near the newspaper. And soon after most of the world is saved (sadly, the blind will remain the one fraction of the world that cannot be saved, efforts to describe the face in words being insufficient. This will confound scholars of the face, in that if a traffic light that comes in contact with the face can be saved, it would seem that a person would not need the sense of sight to be saved in kind. Studies will conclude that the blind, who are used to being excluded from those activities that require vision, will assume this "saving" will not be for them and will have built a kind of psychic wall against the face's ability to save. So an entirely saved world will not be possible until the blind are executed.), you will have your secretary place a phone call to him or her and pass along the message that using his/her face to save the world was your idea and you did it because you always knew his/her face was possessed of such a beauty that it could do the very world-saving that it has done and, "He/She would like it if you would call him/her back."
Get started. Happy Use His/Her Face To Save The World Day!