Greenland Ice Algae May Accelerate Melting More Than Expected

Each year, as spring arrives in the Arctic, the sun's warmth triggers a transformation on the Greenland ice sheet. Snow melts, and patches of brownish algae bloom on the ice surface. These microscopic organisms darken the ice, reducing its ability to reflect sunlight and accelerating melting. While this phenomenon has been observed for years, new research published in Nature Communications suggests that ice algae may be more resilient and capable of spreading than previously thought.

A study led by researchers from Aarhus University and GFZ Helmholtz Center for Geosciences reveals that these algae require only minimal nutrients to thrive. Their ability to store phosphorus – a key element for their metabolism – allows them to colonize larger areas of the ice sheet, raising concerns about their role in ice loss.

Ice algae and their impact on melting

Like plants, ice algae rely on photosynthesis, using sunlight, water and carbon dioxide to produce energy while releasing oxygen. They require trace amounts of nitrogen, carbon and phosphorus to grow. During spring and summer, they form extensive blooms that darken the ice surface. This reduces the ice’s reflectivity, known as albedo, which leads to faster melting.

Previously, scientists believed that limited nutrients on the ice sheet restricted the spread of these algae. However, new findings suggest that the algae’s ability to store phosphorus enables them to persist in nutrient-poor environments, potentially expanding their reach as climate change exposes more ice.

Investigating microbial life on the ice

For years, the Greenland ice sheet was thought to be a frozen desert with little biological activity. But since researchers from Aarhus University and GFZ Helmholtz Center began their investigations in 2020, they have uncovered a thriving microbial ecosystem. Alongside ice algae, bacteria, fungi and even viruses contribute to the complex web of life on the ice.

Despite these discoveries, studying the algae in isolation has been challenging. Traditional methods involved incubating entire microbial communities, making it difficult to determine the specific role of ice algae. Laura Halbach, a researcher at Aarhus University and now a postdoctoral scientist at the Max Planck Institute, developed a new approach to address this challenge.

Tracking nutrient uptake in single cells

To better understand how ice algae function, Halbach and her team used isotopically labeled nutrients to track how individual algae cells consumed and stored essential elements. By analyzing these samples with a technique called secondary ion mass spectrometry (SIMS), they found that the algae not only efficiently absorbed available nutrients but also stored phosphorus for later use.

This discovery suggests that ice algae can sustain themselves even when nutrient levels are low, allowing them to colonize more of the ice sheet than previously thought. With spring arriving earlier due to climate change, new areas of exposed ice could soon become suitable for algal growth, further darkening the ice and increasing melt rates.

A new factor in climate models

The ability of ice algae to expand their habitat raises important questions about their role in the global climate system. Current climate models largely exclude microbial life from ice sheet dynamics, but these new findings suggest that algae could have a significant impact on the pace of ice loss.

As more ice is exposed each year, algae may colonize and darken these surfaces, enhancing melt rates in a self-reinforcing cycle. Integrating microbial processes into climate models could improve predictions of Greenland’s ice loss and its contribution to rising sea levels.

Understanding the role of ice algae in Arctic melting is critical for refining climate projections and assessing how biological processes interact with physical changes in polar environments. As researchers continue to explore this emerging field, their findings will help shape more accurate predictions of the Greenland ice sheet’s future – and its impact on the planet.

Reference: Halbach L, Kitzinger K, Hansen M, et al. Single-cell imaging reveals efficient nutrient uptake and growth of microalgae darkening the Greenland Ice Sheet. Nat Comm. 2025;16(1):1521. doi: 10.1038/s41467-025-56664-6

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source. Our press release publishing policy can be accessed here.

This content includes text that has been generated with the assistance of AI. Technology Networks' AI policy can be found here.