ABOUT 12,000 years ago, as the world warmed after the last ice age, temperatures in the far north plummeted. This was probably caused by a huge injection of fresh water from melting ice sheets.
Could something similar happen over the next century? Most climate scientists would say no, because they expect it to take centuries for the great ice sheets to begin melting in earnest.
But renowned climate scientist James Hansen thinks that with the planet warming more rapidly than ever before, the ice sheets will melt faster, leading to rapid sea level rise. His work suggests that the average surface temperature of the entire planet will temporarily fall as a result, leading to even more climate chaos (see "Sea level rise could lead to cooler, stormier planet").
Is Hansen being alarmist about sea level rise? It will be decades before we know. But a recent study looking at how the climatic changes seen so far compare with predictions concluded that most scientists "err on the side of least drama" (Global Environmental Change, doi.org/jv9). So the next time you see a climate scientist being accused of alarmism, bear in mind that, so far, more extreme projections are tending to be more accurate.
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A climate of cautious prediction
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A climate of cautious prediction
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A climate of cautious prediction
