Re: What if Mars terraforms itself?
As I describe in my talks about past and future Mars, if we only have the patience to wait one or two billion years, the Sun will warm enough to thaw Mars.
Of course, by then the greenhouse effect on Earth will be getting pretty darn bad with the tropical oceans simmering gently and everyone huddling at the now-melted polecaps to survive, so it will be a timely ripening.
(On a serious note, it's nice to see this batch of new work coming out and looking at longer baseline effects on Mars. Makes it look like a real planet rather than a toy!)