Long-term glacier simulations, Kangerlussuaq Glacier, East Greenland: Centennial reconstructions and projections

Land ice is one of the main contributors to global sea level rise. Accurately predicting future sea-level rise requires understanding glacier dynamics on a centennial scale, as glacier flow happens on these time scales. There are few long-term reconstructions of glaciers, calibrated to observations, which bridge the period between the end of the Little Ice Age (around 1900) to the present day, limiting our understanding of present and future retreat and mass loss of glaciers and ice sheets. Here, we are particularly interested in the Kangerlussuaq Glacier, one of the significant contributors to the total ice mass loss, and hence sea-level rise, of the Greenland Ice Sheet over the last few decades.

We propose a framework for reconstructing Kangerlussuaq Glacier over the past century using modern modeling techniques together with historical observations. Our Kangerlussuaq Glacier reconstruction fits present-day data and provides a more conservative estimate of the centennial mass loss compared to other studies. Additionally, it reveals that ice dynamics played the most prominent role in the mass balance of Kangerlussuaq Glacier over the past century. The Kangerlussuaq Glacier reconstruction revealed a clear transition in glacier retreat patterns in the early 2000s, leading to the investigation of calving on a longer time scale.

Our second study shows that calving parameters, which are commonly assumed to be constant, are not. We explore the connection between the evolution of calving parameters and the change in ice mélange over the past forty years. We show that the standard causal relationship between the two does not persist long-term. Based on these simulations and insights, we project the Kangerlussuaq Glacier to 2100 with several calving parameter trajectories. In contrast to previous studies, we find that Kangerlussuaq Glacier is likely to reach a tipping point and retreat further inland within this century.