Pete and The Doctor in “Doomsday”

Look at it, a world of peace. They're calling this the Golden Age.

Who's the President now?

A woman called Harriet Jones.

Ooh, I'd keep an eye on her...

But it's a lie. Temperatures have risen by two degrees in the past six months. The ice caps are melting. They're saying all this is going to be flooded. That's not just global warming, is it?

No.

It's the breach.

I've been trying to tell you - travel between parallel worlds is impossible! The Daleks break down the walls with their sphere...

"Daleks"?

...then the Cybermen travel across, then you lot. Those discs - every time you jump from one reality to another, you rip a hole in the universe! This planet is starting to boil! Keep going and both worlds will fall into the Void!