Institute of Geography study: World has been cooling for 2,000 years

Professor Dr. Jan Esper's group at the Institute of Geography at JGU used tree-ring density measurements from sub-fossil pine trees originating from Finnish Lapland to produce a reconstruction reaching back to 138 BC.

In so doing, the researchers have been able for the first time to precisely demonstrate that the long-term trend over the past two millennia has been towards climatic cooling.

‘We found that previous estimates of historical temperatures during the Roman era and the Middle Ages were too low,’ says Esper. ‘Such findings are also significant with regard to climate policy, as they will influence the way today's climate changes are seen in context of historical warm periods.’

The annual growth rings in trees are the most important witnesses over the past 1,000 to 2,000 years as they indicate how warm and cool past climate conditions were.

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