Following the 2020 global reduction in shipping fuel sulphur, a natural experiment revealed significant changes in marine boundary layer (MBL) cloud properties over the Eastern North Atlantic. These new observations show a ~15% drop in cloud condensation nuclei, leading to fewer but larger cloud droplets. Normally, this would change how clouds reflect sunlight, but an increase in liquid water path (LWP) counteracted these effects. As a result, cloud optical depth and albedo changed very little. Simultaneous shifts in large-scale meteorology, including weaker inversion strength and increased dry air mixing, further complicated attribution of the observed cloud changes. The study suggests that overall, the cooling influence of marine boundary layer clouds seems to be weakening with implications for future climate feedbacks.

The article combines Ku–Ka–W observations from field campaigns spanning the tropics to Antarctica to show temperature-dependent signatures that separate aggregation from riming. As a first cross-latitude synthesis of triple-frequency snow microphysics, the article may serve as a future reference for cloud/precipitation remote sensing and model evaluation.

Atmospheric dust is changing in response to human impacts on climate and hydrology. This paper investigates airborne dust originating from sediments associated with a retreating glacier in Canada, and finds a composition enriched in various metals and metaloids. While the primary focus of this paper is on local health impacts, there may also be wider implications for aerosol-cloud interactions and biogeochemical cycles, should this phenomenon prove to be widespread in response to climate change.