It's true that climate change happened in the geologic past. But usually over tenthousands of years, not in decades. Such fast change never happened before.
EDIT: Image to big to embed it in the post, but this shows in a pretty good way, how much faster we are warming the earth: https://xkcd.com/1732/
Fast change did also happen before and was mostly invoked by massive vulcanic eruptions,releases of big amount gasses ,changes in jetstreams and ocean currents.
But i agree we most likely have a big impact on the current state and must do what we can to lessen our footprint as a species on this earth if we want to keep this an environment we would like to enjoy for the coming thousand years.