Global Catastrophes by Bill McGuire

Author:Bill McGuire
Language: eng
Format: epub
ISBN: 9780198715931
Publisher: Oxford University Press
Published: 2014-07-07T16:00:00+00:00

By 12,000 years ago, sea level was rising far more rapidly than even the most pessimistic forecasts for the next century, possibly by as much as 10m or so in a couple of centuries, and all the time the climate was becoming warmer and warmer—well, almost all the time, that is. The journey from the depths of Ice Age to the current balmy interglacial was a rather bumpy one, and on more than one occasion the ice made a concerted attempt to reclaim centre stage. A little under 13,000 years ago, for example, the rapid retreat of the ice was stopped in its tracks as a new blast of cold initiated a 1300-year‑long freeze, known as the Younger Dryas (to distinguish it from an earlier and less severe cold phase called the Older Dryas). No one is certain what caused this sudden cold snap but one suggestion is that the culprit was a colossal discharge of fresh water from long-gone Lake Agassiz, one of the gigantic glacial meltwater lakes that had accumulated in North America. The catastrophic emptying of this lake into the St Lawrence River, and thence into the North Atlantic, may have disrupted currents carrying warmer waters into polar regions, allowing the climate at higher latitudes to cool and ice to form once again. The Younger Dryas and similar post‑Ice Age cold snaps teach us a couple of important lessons that we would do well to remember as our own world undergoes dramatic climate change. First, the switch from warm to cold and vice versa can occur extraordinarily rapidly, perhaps—according to the latest research—in just one or two years. Second, the disruption of ocean currents can have serious and far-reaching consequences for climate change. Some worrying implications of the latter I shall address in more detail later in this chapter.

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