Past Global Warming

The last time, 3 million years ago, when CO₂ levels were 400 ppm (what they are now), average temperatures were 8.0°C (14.4°F) higher than today and the seas were 40 metres (43.74 yards) higher than today. We are on target for much higher 450 ppm by 2050. Because the oceans are so huge, like a giant heated swimming pool, they take centuries for them to warm up, so the drastic effects will not be immediately noticeable. On the other hand, if we eventually take corrective action, it will require centuries for that to take effect too.

~ Roedy (1948-02-04 age:69) source