Thaw Subsidence in Undisturbed Tundra Landscapes, Barrow, Alaska, 1962–2015

In some regions underlain by ice-rich permafrost, a consistent, long-term increase in ALT under changing climatic conditions is not supported by observations. The apparent lack of ALT may be attributed to soil consolidation from thawing of the uppermost ice-rich permafrost and subsidence of the ground surface. Four plots established in 1962 at Barrow, Alaska, were re-instrumented in 2003 and surveyed annually using differential GPS technology, accompanied by active-layer probing. Elevation change from 1962 to 2003 was within the interannual variability of the 2003-15 period, indicating net stability in the area. Over the 2003-15 period, however, all four plots experienced subsidence trends of 0.4-1.0 cm/year, resulting in a net elevation change of 8-15 cm. Warmer winters and increased snow depth during this period decreased the potential for frost heave. Warmer summers resulted in thaw penetration into the ice-rich transient layer and ice wedges, leading to the net subsidence in recent years. Copyright (c) 2016 John Wiley & Sons, Ltd.