Aside from the theological implications (which people have been fighting about since time immemorial (and might actually cause our extinction)), 99.9% of all species that have ever existed have gone extinct .
The most famous (infamous) of all mass extinctions was the Permian extinction that occurred sometime around 252 million years ago (Ken thinks the world is 6,000 years old, so he wouldn't care about this). According to Wikipedia, the Permian extinction was the effect of climate change:
There is evidence for one to three distinct pulses, or phases, of extinction. Suggested mechanisms for the latter include one or more large meteor impact events, massive volcanism such as that of the Siberian Traps, and the ensuing coal or gas fires and explosions,and a runaway greenhouse effect triggered by sudden release of methane from the sea floor due to methane clathrate dissociation according to the clathrate gun hypothesis or methane-producing microbes known as methanogens. Possible contributing gradual changes include sea-level change, increasing anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.