Temperatures in Greenland were about 1.5 C warmer 1000 years ago than now.
It was perhaps 2.5 C warmer 4000 years ago.
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The mere fact that the Vikings in their primitive cultures not only colonized but thrived in Greenland 800 ad- 1300 is a point the enviowhacko activist love to ignore, or will throw up tantrums, if you even bring it up.