Surface mass balance of the Ward Hunt Ice Rise and Ward Hunt Ice Shelf, Ellesmere Island, Nunavut, Canada

The Ward Hunt Ice Rise and Ward Hunt Ice Shelf, located on Ellesmere Island, Canada, are two of the northernmost land ice masses on the North American continent. Surface mass balance measurements ( excluding calving and subice processes) began in 1959 on the ice rise and in 1966 on the ice shelf but were frequently interrupted, most recently between 1986 and 2002. The surface balance of the ice rise and ice shelf follows the temporal pattern seen on other measured High Arctic glaciers. The overall surface mass losses over the last 45 years have been comparatively low (1.68 m water equivalent (w eq) for the ice rise and 3.1 m w eq for the ice shelf), which reflects their proximity to the Arctic Ocean. Nevertheless, the ice shelf appears to have weakened sufficiently in recent years to raise concerns about its possible disintegration in the near future. The 2002/2003 balance year was the most negative year on record (-0.33 m w eq for the ice rise and -0.54 m w eq for the ice shelf). Dynamical stresses related to wind, wave, and tidal action may further accelerate this process, as open water conditions on the Arctic Ocean become more prevalent. The Ward Hunt Ice Rise has so far remained in a reasonably healthy state in terms of its overall surface mass balance, although its long-term survival is also threatened by current and predicted future climatic conditions.