Hundreds of years? Faster than that. If we just keep burning carbon we'll warm faster than IPCC predictions. Most forecasts assume we decrease. We'd probably l

Hundreds of years? Faster than that. If we just keep burning carbon we'll warm faster than IPCC predictions. Most forecasts assume we decrease. We'd probably lose Boston, New York, San Francisco and Miami this century, or at least chunks of them. It's not just where the waterline is either: what matters is where the water goes in storm surges. Most current coastal cities would be unliveable within a 100 years I think, if we keep on burning carbon and do "mitigation" only, as OP suggested.