A young Swiss scientist named Ulrich Joerin and his colleagues at Institute for Geological Science at the University of Bern have been making news in climate circles with an exciting new theory. (See the well-written article from Der Spiegel: highly recommended.)
Essentially, the idea is that during the last few thousand years, glaciers have come and gone from the Alps repeatedly. When Hannibal crossed the Alps, Joerin and his doctoral advisor believe, there were no glaciers. Only in a brief period (from roughly 1650-1850, known as the Little Ice Age) does Joerin believe these high mountains were fully cloaked in ice. He bases his theory on analysis of chunks of long-downed ancient trees found at the bases of contemporary glaciers. He believes these trees originally were found much higher in the mountains, before the Little Ice Age.
He calls this idea the Green Alps Theory.
Although glacier experts like Hanspeter Holzhauser have been collecting remains of plants in the vicinity of glaciers for years, they only began systematically analyzing the finds about 13 years ago.
At first, he and his students collected over a thousand little chunks of wood and shreds of turf on their excursions along the glaciers, from the Engadin in the east to the Unterwallis in the west, from the Forno and Stei Glacier to the du Mont Mine Glacier. Finds include the remains of birch trees, willows, Norway spruce, pines, larch and a lot of the resilient Swiss stone pine.
There is a simple deduction that lends support to the Green Alp theory: The bits of trees that have been washed out of the glaciers must come from further up the mountain. And if trees grew up there, then the mountains could not have been covered by glaciers.
Not everyone agrees with this theory; one expert cited in the piece points out that it doesn’t match three other evidence samples, from ice cores, pollen samples, and ocean sediments.
But it’s an intriguing idea, and artists already have begun depicting it. Still,before we put global warming in the category of "Why worry? It’s happened before" we might listen to a warning from the climatologist on the subject. Joerin points out:
"Our findings so far could also be seen as giving the exact opposite of a climatic all-clear. If we can prove that there were ancient forests where the glaciers are today, it means one thing in particular: that the climate can change more suddenly than we thought."
Kit Stolz 