Isqar was an ice planet.
In 2007, Professor Mallingan created a dimensional gateway between Earth and Isqar. He was using it to send hot polluted air to, and siphon off cold air from, Isqar to prevent global warming on Earth. Mallingan did not care about the consequences to the natives of the other planet. The Tenth Doctor shut down the machine that was exchanging the air, destroying Mallingan's laboratory in the process. (COMIC: Cold War)