For some time now, I have been fascinated by the growing evidence that the earth’s climate has undergone extremely rapid changes over relatively short periods of time. Although very rare over the past million years, events such those associated with the Bølling-Allerød and Younger Dryas periods (11k to 15k BP) have attracted growing interest, especially in what they can tell us about the sensitivity of the climate to small shifts in forcing factors. Steffensen et al (2008) have just published a fascinating and detailed study of these phenomena within the Greenland NGRIP ice core. In this paper in Science, they report on the rapid switches between glacial and mild conditions that occurred periods as short as 1-3 years! Knowing what we know today, these periods must have been associated with vast disruptions to our planet’s climate and biological systems. It is fascinating to think that this disruption immediately preceded the rise of human civilizations in many parts of the world (adversity spawning invention?). While we do not have any clear understanding of why these events occurred (or for that matter, their impact), they serve as reminders of the volatility of the earth’s climate. Further investigation of these rapid spikes in the earth’s climate will no doubt yield some interesting yet foreboding science.

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