As we have seen in question 2, the conclusion that abrupt climate changes have occurred in the past is almost impossible to avoid. Their timing, however, is rather difficult to pin down, due to the inherent imprecision of geochemical dating methods (decay of radioactive elements such as carbon 14 or uranium series). Nonetheless, the analysis of annually banded records (ice cores, corals, tree-rings, or speleothems) has firmly established the rapid rate of these changes.

The ubiquitous character of certain events further confirms their importance: "the Younger Dryas and a large number of abrupt changes during the last ice age called Dansgaard/Oeschger events (23 abrupt changes into a climate of near-modern warmth and out again, during the last glacial period) have been corroborated in multiple ice cores from Greenland, Antarctica and tropical mountains, marine sediments from the North Atlantic Ocean, the tropical Atlantic, eastern Pacific, and Indian Oceans, and from various records on land.  Other, smaller abrupt changes have been linked to societal disruptions. Evidence for some of these events are more regional in nature, and points to far less dramatic changes. However, these events did occur so rapidly and unexpectedly that human or natural systems had difficulty adapting to them - the second definition of abrupt climate change." (source: NOAA Facts Sheet)

Thus, while we like to find evidence of large events in many distant locations, local changes can be instructive examples of abrupt climate change, if properly dated.