The projected rate of warming [4oC+ CO2 600ppm+] for the 21st Century under business as usual is easily 60 times faster than the rate of the 4oC to at most 5oC global average warming during the 8,000 year emergence from the last ice age [or 160 times faster than the PETM 55.6m years ago]. That's a 1oC rise in global average temperatures every 26 years in the 21st Century. In the exit from the last ice age it was a gradual 1oC rate every 1,600 to 2,000 years, cumulating to a 4oC to 5oC from a 100ppm CO2 rise in 8,000 years, and 120 meter sea level adjustment over 11.000 years.
The warming since 1970 to 2010 has been 15 times faster, and the increase in atmospheric CO2 120 times faster than the exit from the last ice age. The 21st Century projected rate of CO2 increase is 300 times faster for business as usual, and 60 times faster under the 450ppm overshoot 2oC scenario. These abrupt changes mean accelerated change in the cryosphere, and sea levels. NASA Ice Viewer
Multi-meter sea level rise per century has often happened in paleoclimate for global average warmings 60 times slower than that forecast in the 21st Century. [Diagrams: Antarctic Ice sheet formation, Global surface temp 65m years, 35m year sea level record]