Driftwood offers climate secrets

Last updated 14:14 04/02/2013

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Massive deposits of driftwood lining Arctic shores may be an untapped trove of clues about past climate and ocean currents.

Although no forests line the shoreline of the Arctic Ocean, plenty of wood ends up there after floating to sea via rivers that drain Eurasia and North America.

In recent field studies conducted at two sites in eastern Greenland and one in the Norwegian archipelago of Svalbard, researchers collected 1445 samples of driftwood that had originated in distant regions.

A little less than half of the samples came from cut logs, a sign that they had escaped from logging operations, but most of the rest - including parts of mature trees more than 50 years old - had wafted seaward after falling into rivers naturally by erosion due to strong storms or river flooding.

The wood that the team analysed came from trees of seven different genera, with conifers accounting for about 88 per cent of the samples.

About 40 per cent of the samples came from pine species found only in Siberia, the researchers report online and in a forthcoming issue of the Journal of Geophysical Research: Biogeosciences.

If the origin and age of driftwood samples can be ascertained, either by studies of tree rings or by carbon dating, then scientists might gain insights into long-term variations in river runoff and regional climate, as well as fluctuations in the strengths and paths of ocean currents.

Also, by analysing samples that had accumulated along ancient shorelines that now sit well above sea level, the scientists might be better able to estimate how quickly the landscape has risen in recent millennia after being relieved of the burden of ice sheets that melted at the end of the last ice age.


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