September 18, 2009
Is Global Warming a Con?
Is the world getting warmer or cooler. It’s getting cooler if you look back 1000 years – but not if you try a bit harder and go back to the time of Christ. Arctic temperatures are now higher than at any time in the last 2,000 years, research reveals.
Changes to the Earth’s orbit drove centuries of cooling, but temperatures rose fast in the last 100 years as human greenhouse gas emissions rose.
Scientists took evidence from ice cores, tree rings and lake sediments.
Writing in the journal Science, they say this confirms that the Arctic is very sensitive both to changes in solar heating and to greenhouse warming.
The 23 sites sampled were good enough to provide a decade-by-decade picture of temperatures across the region.
The result is a “hockey stick”-like curve in which the last decade - 1998-2008 - stands out as the warmest in the entire series.
“The most pervasive signal in the reconstruction, the most prominent trend, is the overall cooling that took place for the first 1,900 years [of the record],” said study leader Darrell Kaufman from Northern Arizona University in Flagstaff, US.
“The 20th Century stands out in strong contrast to the cooling that should have continued.
The last half-century was the warmest of the 2,000-year temperature record, and the last 10 years have been especially dramatic,” he told BBC News.
On average, the region cooled at a rate of 0.2C per millennium until about 1900. Since then, it has warmed by about 1.2C.
Much debate on climate change has centred on the Mediaeval Warm Period, or Mediaeval Climate Anomaly - a period about 1,000 years ago when, historical records suggest, Vikings colonised Greenland and may have grown grapes in Newfoundland.
The new analysis shows that temperatures were indeed warmer in this region 1,000 years ago than they were 100 years ago - but not as warm as they are now, or 1,000 years previously. But that is not the answer scientists want us to hear. So we go back further, ignore the fact that climate is cyclical and we are still emerging from the last ice age…. And press the panic button.
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