Accelerating glacier volume loss on Juneau Icefield driven by hypsometry and melt-accelerating feedbacks

Area of Science:

• Glaciology
• Climate Science
• Earth System Science

Background:

• Glaciers and icefields are major contributors to global sea level rise.
• Understanding regional ice loss dynamics is crucial for climate change projections.

Purpose of the Study:

• To analyze the acceleration of ice loss from the Juneau Icefield, Alaska.
• To investigate the mechanisms driving increased melt rates and thinning on the icefield plateau.

Main Methods:

• Analysis of historical and recent glacier volume and area change data.
• Assessment of thinning trends across the icefield plateau.
• Investigation of feedback mechanisms, including equilibrium line altitude and ablation rates.

Main Results:

• Ice loss from Juneau Icefield accelerated markedly after 2005.
• Area shrinkage rates increased fivefold between 1979-1990 and 2015-2019.
• Glacier volume loss more than doubled after 2010, reaching 5.91 ± 0.80 km³ a⁻¹ (2010-2020).
• Pervasive thinning and fragmentation of glaciers on the plateau were observed.
• Rising equilibrium line altitudes and increased ablation drive melt-accelerating feedbacks.

Conclusions:

• Accelerated mass loss is driven by melt-accelerating feedbacks on the icefield plateau.
• Continued thinning may inhibit future glacier regrowth, potentially leading to a dynamic tipping point.
• The findings highlight the sensitivity of plateau icefields to climate warming and their contribution to sea level rise.