I was hearing the Fully Charged podcast recently, and a guest said something so simple and yet so optimistic. We don't have to be 100% renewable, we just have to 90% renewable and there is huuuuge difference between the two. The latter can be done even with today's technology. Keep the peaking plants online for emergencies and all. Just don't burn fossil fuels in them until its absolutely necessary.

Remember, almost half the emissions ohr civilization has made, have been absorbed by natural systems. We cannot push the Earth much further, but we can also expect to see significant changes in CO2 levels as the emissions go down At 90% reduction, across the board, we can expect to be on a permanent path to pre industrial CO2 levels.