Just seen in a comment: 

Fossil fuels are made from once living things and burning them releases their joy back into the world

Think about it. All that carbon locked up in fossil fuels is unavailable to photosynthesis and hence life's food chain. We're setting it free to be turned back into life. What's a few millennia and extinctions between friends?

Which raises the question. If the industrial and anthropogenic total use of fossil fuels and other resources wipes us out, how many millions of years would it take to lay down another fossil fuel supply and for another intelligent animal to appear to make use of it?