What do meltwater surges at the end of the last Ice Age tell us about the manmade climate change that is happening today?
"The crime under investigation happened more than 14,000 years ago — a cold case in more ways than one. It was a time when the great Laurentide ice sheets that covered vast stretches of North America had begun to melt, as the most recent Ice Age gave way to the current, relatively warm planet we now live on. At the glaciers’ greatest extent, maybe 4,000 years earlier, so much water was locked in the ice that sea level was more than 300 feet lower than it is now. As the glaciers retreated, the ocean rose at a mostly stately pace.
But then, abruptly, the sea started rising a lot faster, in an explosive episode of ice loss known as MWP-1A (for “meltwater pulse 1A”). Then, after less than a thousand years, it stopped.
The whole thing would have no more than historical, or prehistorical, interest, except for one thing: the sea is rising again, and nobody is quite sure how fast or how high it will go. Thanks to heat-trapping, human-generated greenhouse gases, oceans have already gone up an average of 8 inches over the past century or so worldwide. In the U.S. alone, that translates into a threat for millions of Americans. Sea level is bound to go higher, partly because water expands as it warms, but also because the ice that remains in Greenland and Antarctica is both melting and sliding into the ocean as it warms."
Michael D. Lemonick reports for Climate Central March 30, 2012.
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