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Above: Khan collecting data on the Greenland ice sheet.
Header Image: A channel of flowing water on the ice sheet.

Alia Khan is integrating field-based biogeochemical analysis with NASA’s next generation satellite sensors to quantify how biological algae blooms, mineral dust, and wildfire smoke are darkening the Greenland Ice Sheet and accelerating its melt.

Khan, an associate professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences and the Environmental Engineering Program at the University of Colorado Boulder, has been awarded a four-year, $857,000 NASA grant to develop tools to improve sea-level rise projections.

The work is focused on Greenland, home to massive amounts of frozen water in a large land-based glacier, also known as an ice sheet, that is nearly two miles thick in some places.

Increasing melt rate

“There are growing dark spots on the Greenland Ice Sheet,” Khan said. “While fresh snow is the most reflective surface on Earth, the ‘bare ice’ exposed during summer melt is naturally darker. When light-absorbing particles like algae and dust accumulate there, they further reduce reflectivity and cause the ice to melt even faster. Currently, this darkening isn't fully captured in most Earth system models, meaning we are likely underestimating future sea level rise.”

The enhanced darkening of the ice sheet is caused by the combined impact of soot, mineral dust, and seasonal ice algae blooms. These particles significantly increase heat absorption, creating a feedback loop that intensifies surface melting as the Arctic warms.��

“Wildfires are becoming more frequent and intense, sending plumes of soot to settle on the ice,” Khan said. “At the same time, retreating glaciers leave behind fine dust that the wind blows back onto the surface. These particles, along with algae fueled by increased meltwater nutrients, are transforming the ice sheet from a reflective shield into a heat-absorber.”��

New technology

To measure the impact, Khan is leveraging NASA’s . Launched in 2024, PACE provides high-resolution hyperspectral imagery—capturing a vast spectrum of light from ultraviolet to infrared—to reveal details of the Earth’s surface that were previously invisible to orbiting sensors.

“PACE’s hyperspectral technology allows us to tease apart the unique spectral signatures of mineral dust and living algae,” Khan said. “By mapping these specific characteristics, we can determine exactly how each one contributes to surface melt, allowing us to improve our predictions for the future of the Greenland Ice Sheet.”��

Khan will combine this data with planned in-person surveys of the Greenland ice sheet using drone flights and collection and analysis of surface samples of snow and ice.

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Sailboats amidst icefloes off the coast of Greenland.

“The samples will be used to validate the satellite imagery and to measure specific quantities of dust, black carbon, and algae. This includes analyzing a suite of photosynthetic and photoprotective pigments, as well as conducting DNA analysis,” she said.

Like nowhere else

Spending time on the ice sheets is a unique and rare opportunity. Accessible only via helicopter, they are places few humans have seen up close.

“There’s a pretty significant wind chill and survival gear is necessary, whether or not we plan to spend the night, but it’s such a privilege to work in a place almost completely untouched by humans,” Khan said.

The collected data and images will be used in the creation of complex new algorithms to more accurately map the dark zones throughout the melt season.

“It takes a lot of computing power, but there’s so much exciting new technology we can apply here to build models we haven’t had before,” Khan said.

As Greenland's ice loss remains a primary driver of global sea-level rise, by refining our understanding of Greenland’s melt rates, Khan’s work fills a critical gap in the climate models used by scientists and policymakers to improve future projections.

Additional investigators on the grant include Peng Xian at the U.S. Naval Research Laboratory and Heidi Dierssen at the University of Connecticut.