I believe GP was referring to the heat death of the universe [0], which might be paraphrased as the death of heat in the universe, rather than lifeforms on one planet dying when the environment becomes too hot for said lifeforms to survive.
I should have been clearer; I trying to note the irony of saying "heat death of everything" could be a much shorter timeframe than we usually mean when we say that phrase, if Hansen's forecasts turn out correct.
[0] http://www.physlink.com/education/AskExperts/ae181.cfm