Greenland's ice loss is being silently accelerated by airborne dust.

The warmer air isn't the only reason why Greenland's ice is melting. By feeding dark algae blooms that absorb sunlight and accelerate ice loss, tiny particles carried by the wind can subtly alter surface conditions.

That begs the straightforward question, "Where do those blooms get the nutrients they need to grow on bare ice?"

According to recent studies, an essential component is immediately applied to the surface by mineral dust in the air. When it lands, the dust aids in the spread of algae, which darkens the ice.

This darkening eventually starts a series of events that cause Greenland to melt more quickly than it otherwise would.

Particles of dust that cause ice melt

Dark spots of algae grow across regions that would normally reflect sunlight as a direct result of this process on exposed ice surfaces.

Dr. Jenine McCutcheon and colleagues at the University of Waterloo (UWaterloo) revealed how windblown particles arriving from neighbouring land become buried in active melt zones by gathering dust and biological material on the ice itself.

Algal growth patterns that could support dense, pigmented communities throughout the melt season were consistently correlated with those deposits. The results lay the foundation for a closer examination of how that process operates by establishing a local, repeatable relationship between what falls from the air and how rapidly ice darkens.

On the naked ice, dark flowers

Where pigmented glacier algae accumulated on bare ice, dark streaks developed, and those areas absorbed significantly more sunlight than pure ice. Albedo decreased as the algae darkened the surface, which made it possible for the ice to hold onto more heat and melt more quickly.

Algae were subsequently able to access light and nutrients thanks to melt water spreading across the surface, which accelerated their growth and intensified the darkening effect. Only in areas where ice stayed exposed for an extended period of time did that feedback function; strong rain or late snowfalls could interfere.

Dust was the substance that was missing. The team discovered phosphorous, a crucial ingredient needed to create genetic material, inside the wind-blown particles.

According to their calculations, each square metre receives roughly 1.2 milligrams of phosphorus annually, which is sufficient to support dense algal colonies.

The researchers estimated that algae may reach about 8,600 cells per millilitre with that nutrition supply, a quantity that could hasten melt and quickly discolour ice.

The wind carries dust.

The dust grains' chemical traces indicated that they originated in neighbouring ice-free plains rather than far-off deserts.

Wind carried aerosols—tiny particles floating in the air—from nearby land and deposited them on snow or bare ice as glaciers receded and exposed more bare terrain.

Larger grains were typically dropped by snowstorms, but finer dust that might float for days was brought about by dry settling. Future melt seasons may start with even more raw material for algal development as the local ground gets drier.

The same air currents that carried this dust also carried algae, according to air samplers close to the field camp. When the snow starts to melt, some of the cells that had settled on it may divide and begin to colour the snow's surface.

According to Dr. McCutcheon, "the cells are probably carried over the ice by wind, providing a mechanism for these organisms to be dispersed and grow on new snow and ice surfaces further afield, helping new algal communities get started."

That shared airborne pathway makes bloom expansion difficult to contain, allowing wind to spread living starter populations across miles of ice.

Seas rise when ice melts.

Greenland's lost ice doesn't stay there, and the additional water is felt as rising seas in coastal cities. NASA records link the ice loss in Greenland since 1992 to an increase in sea level of roughly 0.4 inches. During one melt season, glacier algae increased flow from bare ice in the southwest by about 10 percent.

When dust feeds those blooms, models that ignore biology can miss where melt water will surge and when it will peak.

Soot makes ice melt worse.

Tiny soot particles also fell on the ice along with mineral dust, and they have the potential to further darken it. Black carbon and soot particles are among these particles; they absorb sunlight strongly, warming the surface and accelerating melting.

According to McCutcheon, her team also collected samples of soot that fell from the sky, and smoke from wildfires can increase that load. When dust and soot arrive at the same time, their combined darkening can push the ice over a threshold where melting occurs more quickly.

Forecasts overlook important elements

Although temperature and snowfall are already monitored by forecast teams, it now seems that microorganisms and nutrients are elements that these forecasts continue to overlook.

This new study followed that supply channel into the atmosphere, confirming previous field experiments that mineral phosphorus might trigger glacier-algae blooms.

McCutcheon may compare those findings with laboratory tests at UWaterloo that demonstrate the rate at which dust minerals release nutrients in melt water. Although they require more on-ice sampling during brief, hectic summers, improved inputs could aid agencies in planning for flooding.

What researchers still require

Because the study only looked at a single, rapidly melting region of Greenland, it was unable to fully capture the behaviour of dust and algae throughout the entire ice sheet.

This is significant because more comprehensive evaluations caution that Greenland may surpass size thresholds where reversing ice loss would be challenging for centuries.

NASA's satellites already monitor variations in ice colour and surface elevation, but they still require on-the-ground chemistry to explain why surfaces darken.

Long-term forecasts will be highly uncertain until scientists are able to monitor biological activity, dust, and soot all at once, particularly for upcoming decades.

The interdependence of these forces is becoming more evident. Soot can increase the absorption of sunlight, dust can transport nutrients, and wind can disperse microorganisms—all of which contribute to the same melt cycle.

More field sampling seasons, according to researchers, will be required to determine when this chain pauses or starts to accelerate.