Permafrost Destabilization and Thermokarst Following Snow Fence Installation, Barrow, Alaska, U.S.A

Abstract

ABSTRACTIn autumn 1997, a 2.2 km-long, 4 m-high snow fence was constructed east of the coastal village of Barrow, Alaska. A large drift develops each winter on the downwind side of the fence, and a smaller drift forms upwind. To monitor the thermal impact on ice-rich permafrost, nine monitoring sites were installed near the fence in 1999 to measure soil temperature at 5, 30, and 50 cm; an additional three sites were located in the undisturbed tundra as a control. Maximum thaw and snow depth were measured annually. The results of the 6-yr study indicates that soil temperatures beneath the drift are 2 to 14°C warmer than the control in winter due to the insulting effects of the snow. Since the drift persists 4 to 8 wk after snow has disappeared from the undisturbed tundra, soil thaw is delayed and soil temperatures in summer are 2 to 3°C cooler than the control. The mean soil temperature over the 6-yr period of record has warmed 2 to 5°C, and the upper permafrost has thawed. The ground surface has experienced 10 to 20 cm of thaw subsidence in many places, and widespread thermokarst is apparent where snow meltwater ponds. Both direct soil warming and the indirect effects of ponding contribute to local permafrost destabilization.