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 © 2016 John Wiley & Sons, Ltd.