Final answer:
The best-documented climate surprise related to the Atlantic Meridional Overturning Circulation in paleoclimatic archives is the Younger Dryas event, evidenced by Antarctic ice core data indicating temperature and CO2 levels.
Step-by-step explanation:
The best-documented climate surprise in the paleoclimatic archives associated with the Atlantic Meridional Overturning Circulation (MOC) is known as the Younger Dryas event. This event was a prolonged warm period whose cause is still debated, but theories involve changes in ocean circulation and reduced levels of atmospheric CO2 leading to the expansion of the Antarctic ice sheet and global cooling. Evidence for this and other climate changes over Earth's history is derived from various sources such as Antarctic ice cores, which contain trapped air bubbles providing temperature and carbon dioxide data going back over 400,000 years.