The springtime darkening of the Greenland ice sheet since 2009 may be attributable to an increase in the amount of impurities-such as dust-in snow, according to a study published online in Nature Geoscience. Impurities, which increase the solar energy absorbed by snow, can lead to enhanced melting and thus contribute to the loss of Greenland’s ice.

Marie Dumont and colleagues analysed satellite observations to show that the observed darkening of Greenland’s ice in springtime months is consistent with a widespread increase in the amount of light-absorbing impurities. They propose that dust originating from other Arctic areas, which are losing their snow cover earlier in the spring as the climate warms, may be the source of the impurities.

Numerical snow models suggest that the darkening of springtime snow due to light-absorbing impurities has led to significant mass loss of the Greenland ice sheet in recent years.