C3: Findland's Treelines Establish Past Warmer Periods In High North: Researchers Confirm Current Temps Cooler

Treeline reconstructions are a superior means to determine overall long-term temperature changes versus tree-ring widths. Using treelines, researchers can determine past growth areas for tree species.

Finnish researchers using pollen samples and fossils were able to reconstruct the Scots Pine tree growth areas as far back as 6,000 years before the present. These trees prefer warmer temperatures than today's High North offers, but in the past their range extended much farther north indicating temperatures were at times some 2.0+ Celsius degrees higher.  [During any of these warm periods, did polar bears go extinct?]

Letters: Challenging times for climate science | Environment | The Guardian

You report (Cold snap does not undermine climate case – scientist, 12 January) that Professor Mojib Latif of Kiel University, a leading member of the Intergovernmental Panel on Climate Change, has attacked as "misleading" my article in the Mail on Sunday (10 January), stating that I wrongly claimed that his work "undermines the scientific case for manmade global warming".

At no point in my piece did I say that it does. I merely quoted him, accurately, saying that his team's work suggests that up to half the global warming observed in recent decades was due not to greenhouse gases but long-term ocean temperature cycles. These, he went on, have now entered a "cold" mode, and that as a result, we can expect more cold winters and a slight, though temporary, cooling. Prof Latif told me: "Global warming has paused," adding that the extreme glacial retreats and icecap melting seen recently would for the time being cease.

Such predictions, I wrote, "challenge some of global warming orthodoxy's most cherished beliefs", including the assertion that the north pole will be ice-free in summer by 2013. Latif told me that this is most unlikely to be realised. His work may not undermine the science of manmade warming, but it does challenge standard media representations of its imminent consequences.

David Rose

Climate sceptics distract us from the scientific realities of global warming | John Cook | Environment | guardian.co.uk

One might reasonably question whether the goal of surfacestations.org was to lead us into greater scientific truth or merely to sow doubt about the temperature record. Nevertheless, their efforts to rate each individual weather station enabled scientists to identify a cool bias in poor sites and isolate the cause. A net cooling bias was perhaps not the result the surfacestations.org volunteers were hoping for, but improving the quality of the surface temperature record is surely a result we should all appreciate.