Tim Radford in Responding to Climate Change: The Arctic is now, and has been for the last 100 years, warmer than at any time in the last 44,000 years and perhaps for the last 120,000 years.Good news for Arctic mosses, if not for any other Arctic creatures: little tundra plants that have been buried under the Canadian ice can feel the sunlight for the first time in at least 44,000 years.
This means that the Arctic is warmer now than it was in what geologists call the early Holocene, the end of the last Ice Age – when the peak summer sunlight was roughly 9% greater than it is today, according to Gifford Miller of the University of Colorado Boulder, in the US.
“The key piece here is just how unprecedented the warming of Arctic Canada is. This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere,” said Miller. The mosses studied by Dr Miller, of course, could feel nothing: they were dead. But they could tell a story, all the same.
The Arctic ice cap has been in constant retreat for the last century, and glaciers almost everywhere have been melting: there are fears that the process has begun to accelerate as greenhouse gases concentrate in the atmosphere. But as the ice recedes, it exposes evidence of the past, preserved over the millennia in the natural deep freeze.
The researchers used a technique called radiocarbon dating to establish that the mosses had been screened from the elements for at least 44,000 to 51,000 years. Since radiocarbon dating is only accurate for about 50,000 years, the mosses could have been buried for perhaps 120,000 years, since the last “interglacial” when the polar regions experienced a natural thaw....
Arctic ice shot by Pink floyd88 a, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license
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