Al Gore's head

Al Gore was, during the end of 20th century, the Vice President of the United States serving next to Bill Clinton, and leader of the secret Vice Presidential Action Rangers. In the 31st century, he has become the first Emperor of the Moon and the inventor of the environment.

In the 20th Century
Al Gore was leader of the Vice Presidential Action Rangers. Other members included Stephen Hawking, Nichelle Nichols, Gary Gygax, and Deep Blue. It was their duty to protect the fabric of the universe against destructions. Since there is a space-time nexus at the point where Fry is frozen, Fry not getting frozen could start a reaction that could destroy the universe. Thus, in a What-If scenario, Al Gore and his Action Rangers ensured that Fry is indeed frozen and sent to the future. Fry, however, not wanting to go to the future (after having seen "monsters" in a Fry-hole), destroyed the freezer tube, and the universe disappeared shortly thereafter.

In the 21st Century
Al Gore won the presidential election of the year 2000, however Bender entered the vote counting room and blew up the basket with Gore's thousands of votes in it, making George W. Bush the winner of the election. Later on in the century as a part of his campaign to protect Earth from global warming he opened his own Hybraxi service (Hybrid taxies). One of his customers was Bender who paid him $100 to catch Fry in another taxi, however Bender made Gore crash the Hybraxi.

In the 31st Century
Al Gore survives in the 31st century as a head in a jar. He is emperor of the moon (and claims to have ridden the mighty moon worm), and has written at least two books. As a prominent environmentalist, he is asked to speak at a symposium, which is meant to solve the problem of global warming.

Trivia

 * Al Gore was probably convinced to do his appearances by his daughter, Kristin Gore, who works as story editor on the show.
 * Al Gore listed Futurama as one of his favourite shows prior to his appearance or his daughters' working on the show.
 * Al Gore has written a sequel to his 1992 book "Earth in the Balance" entitled "Harry Potter and the Balance of Earth", which was much more popular.
 * In the credits, he is listed as "Vice President Al Gore"
 * The real Al Gore's 2006 documentary movie An Inconvenient Truth had a Futurama style trailer.
 * On a related note, the movie An Inconvenient Truth has a clip from the episode Crimes of the Hot where they drop giant ice cubes into the ocean.
 * See also in popular culture.
 * In the 31st century, Al Gore is on the $500 bill, in place of William McKinley.

Quotes
Fry: Good for him.
 * Al Gore: The universe would be destroyed! And as an environmentalist, I'm against that.
 * Al Gore: I have ridden the mighty moon worm!