IPCC report 5.5.2 for the two thousand years prior to the invention of writing, summer ice in the Arctic Ocean was *less* than it is even at reduced 21st century levels. Likewise, glaciers were shorter in those times than they are now, even at their reduced lengths after several decades. 8,000 years may seem long ago to most people, but to me it seems like just yesterday, and to geologists and biologists it is but a blink of an eye. At the time human civilization as we know it was starting up, there was less ice than today, and they not only coped but flourished! Summer sea ice cover between 8 ka and 6.5 ka was reduced compared to late 20th Century levels both in the Arctic Ocean and along East Greenland. There is medium confidence that the modern ice loss and increase of sea surface temperatures in the Arctic are anomalous in the perspective of at least the last two millennia. [5.5.2] The current near-global recession of glacier length is unusual in the context of the last 2 millennia [medium confidence] and consistent with reconstructed surface-temperature anomalies. Retreating glaciers are still larger now than in the early-to-mid Holocene in most regions (high confidence). [5.5.3]
Posted on: Fri, 27 Sep 2013 11:41:27 +0000
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