Obviously it won't be the death to everything, but it is a serious threat. The biggest difference now to how it was before is that countries like China/India/Brazil and the African countries are having a huge impact on how the world as a whole develops. These countries are just focusing on growing rapidly, which they fuel with none sustainable resources (like coal, look at China). Earlier in history these countries were so underdeveloped that their global impact was negligible.
That's the greatest reason to why we have seen such an increase in fossil fuel emissions, and is why changes are happening as rapidly as they are at the moment. The people in the west have basically lived as they have done before. But EU and NA combined is only a small portion of the global population.
That is also why we see such rapid changes in sea levels etc, that won't mean the death of everything, but will affect animal life and stuff like that