My point was that a 2 degree change in the atmosphere now isn't so extreme for a 1+ billion year old organism as all the other history it has lived through.

I'm not trying to brush off the impact of global warming, I'm just placing it in the context of 1+ billion years of Earth history.

That's the point?

Anything that has survived for a billion years in a form that could still be considered roughly the same organism or a close descendant must have a relatively stable biochemistry and gene pool that is capable of surviving an extreme range of environmental changes - as close as you can get to a holy grail in natural selection.

Obviously its survival would not be inevitable; not even stars can survive their own age.

You have the math backwards. If there are events that kill 99% of everything and a million such events occur, then the survivors must be hardy in the face of shock. Global warming won't kill them; they've already been through incidents of far worse warming and cooling.