Cooper Island, Alaska, Aug. 9, 2009 — Driftwood lines in the middle of Cooper Island are important for nesting terns and waterfowl, but in any given year there typically has been little accumulation of wood on the island’s beaches. Until recently, the short duration and limited amount of ice-free water were not conducive to movement and deposition of driftwood. Hundreds of miles north of the tree line, driftwood on Cooper Island apparently comes primarily from the Mackenzie River. When the Beaufort Sea had limited open water, wood coming out of the Mackenzie would likely have had little chance to drift before it was frozen into the pack ice in the fall. Once frozen into the ice it might have stayed there for years given the minimal retreat of the pack ice in past decades.
This year’s unprecedented accumulation of driftwood on Cooper Island is one more sign of change in the Arctic. As the ice melted over the past month, pieces of wood that had been frozen in the ice are frequently seen floating offshore as they approach the island and now form a substantial line of driftwood along the entire north side of the island. It will take major fall storms to lift this wood higher on the island where it can provide nesting habitat. For now it provides some diversity during walks on the north beach.