S5, E16: When the Atlantis team is given two weeks of vacation leave Dr. Rodney McKay reluctantly accepts an invitation by his former rival Malcolm Tunney to attend a scientific demonstration that he claims will be the solution to global warming. Feeling bold he asks Dr. Jennifer Keller to accompany him and she accepts. Upon reaching Earth they are flown by private lear jet to a top secret facility in the middle of a desert. Once there McKay is shocked by Tunney's brazen claims that he's invented a device that can cool the Earth by venting excess heat from our space/time into another space/time - an idea McKay had already pursued two years earlier. Despite Rodney's mounting concerns over its safety Tunney activates his new technology dropping the heat contained inside the facility by 10 degrees. But when the device reaches this goal and will not disengage McKay realizes he has to work fast or every one trapped inside the premises will freeze to death within the hour.