Geo-engineering – direct intervention in the atmosphere to hold the temperature down while we work on getting emissions down – will probably be needed. Nobody really wants to do solar radiation management, but cutting the amount of sunlight reaching the planet’s surface by just a small amount is technically feasible. It could temporarily halt the warming and give us the extra time we are probably going to need.
We are getting into very deep water here, but we may have no other options. If we had started cutting our emissions 20 years ago, such drastic measures would not be necessary. But that’s not the human way, and so we’ll have to take the risks or pay the price.