In it's 4 billion or so years of its existance, Life has come through many
catastrophes. Meteor impacts, ice ages, oxygen pollution - all took the lives of
individuals and
species and
populations. Life, however, continued on;
the dinosaurs died and the mammals replaced them,
anaerobes were driven underground by the pollution of the
aerobes - who now dominate the surface.
To be blunt, I cannot think of a single catastrophe that would destroy all Life. Even the eventual death of the sun would only mildly inconvenience those organisms that live underground, eating rocks. Never mind cockroaches surviving thermonuclear war, there are bacteria that might have been designed to survive radiation* (Deinococcus radiodurans). Considering some archae can survive the boiling, sulphorous springs of yellowstone I doubt they will be worried by even a doubling of global temperature.
It is important to realise who loses in this happy vision of resiliant life. Sadly, it is us - we are neither resistant to radiation nor tolerant of temperature extremes. Oh, womankind may survive - but the possibility that the bottleneck of 60,000 years ago, where a few thousand humans survived a supervolcano, might come again. 'Save the planet' is a joke; if we want to be concerned about climate change or pollution or nuclear waste natural or not we should be thinking :
Save the Humans
*
Gritchka has pointed out that a
gamma-ray burst
in our galaxy would destroy the life on one side of the planet. Obviously, a
meteor the size of the
moon might even break up earth, which would be bad. I exaggerate here.