This quote describing a prediction by James Lovelock makes clear what the previous statement implies.
Recall that current climate models predict major effects from just a few degrees Celsius change. Are these purely hypotheses, or is there any evidence for abrupt climate changes?
The American Institute of Physics (AIP) provides an excellent summary of how data and the beliefs of earth scientists have evolved over time. The answer provided to the above question is a definite "yes."
Scientists became ever cleverer and more precise in interrogating the earth to determine historical records of temperature changes.
A shocking moment came when two groups extracted ice cores from deep within Greenland’s ice field. The cores were taken from locations 30km apart and, arriving at the same results, confirmed each other’s surprising results.
It was necessary to determine if these variations could be found in other locations in order to associate global change with the Greenland observations.
Once the data was in hand, scientists began to hypothesize about possible causes. They were able to identify a disturbingly large number of potential triggers. It was also recognized that existing climate models were not likely to be able to predict such rapid transitions. In the simplest words possible: small things can have big effects, and one thing can lead to another.
Hardly a day goes by that there isn’t some news release discussing the thinning arctic ice cap, surprisingly rapid melting of the ice fields of Greenland and Antarctica, changes in oceanic flows, massive icebergs breaking off and floating away—all potential signs of accelerated climate change. One might want to start paying close attention.
The purpose of this piece was to give the reader something else to worry about besides the sorry state of the world’s economy. Now—don’t you feel better?