Recent extreme near-surface permafrost temperatures on Svalbard in relation to future climate scenarios

[1] Here we report extreme near-surface permafrost warming resulting from a remarkable temperature anomaly during winter and spring 2005–2006 on Svalbard. We demonstrate that this atmospheric temperature anomaly fell well within the range of predicted warming scenarios for the late 21st Century. The mean December to May air temperature on Svalbard was as high as −4.8°C, some 8.2°C above the 1961–1990 average. The 2006 mean ground temperature at the permafrost table in a monitored borehole in bedrock was 1.8°C higher than the mean for the previous six years, and this corresponded to a 40% reduction in accumulated annual negative degree-days at that depth. The thermal response was detectable to a depth of at least 15 m. In future, a greater frequency of high-temperature anomalies such as this, superimposed on a warming trend, is likely to cause potentially hazardous irregular acceleration in near-surface permafrost thawing.