Algae Darkening the Greenland Ice Sheet Increases Melting

Nature Communications, 16 June 2026

This study produced the first Greenland-wide model of glacier algae, showing that these microscopic organisms can grow around almost the entire edge of the ice sheet wherever melting exposes bare ice. Between 2000-2022, glacier algae expanded by nearly 3,700 square kilometers each year between 2000-2022, revealing a small but persistent increasing trend. As the algae grow, they darken the ice surface, causing it to absorb more sunlight instead of reflecting it back into space. This “dark ice” effect increases melting and creates a feedback loop in which more melting exposes more bare ice, allowing algae to spread further. During extreme melt years, such as 2019, algae covered larger areas, reached higher concentrations, and extended farther inland. The study also highlights northern Greenland as an emerging hotspot for future algal growth. Over the past three decades, the area of northern Greenland where summer melting exposes bare ice has expanded by 46%, creating more ice surfaces where algae can thrive. While important uncertainties remain, the findings suggest that continued warming will allow glacier algae to expand across larger areas of the ice sheet, further increasing Greenland’s ice loss and resulting global sea-level rise.

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