Sulfur signals in the Antarctic snow have revealed the importance of overlooked atmospheric chemistry for understanding climate, past and future.
The element sulfur is everywhere and occurs in four stable forms, or isotopes, each with a slightly different mass. Ordinary reactions incorporate sulfur isotopes into molecules according to mass. But sometimes sulfur divvies up differently so that the relative ratios of the different isotopes is anomalous. The authors of a new paper measured the direction and degree of that anomaly for individual layers of snow representing a single season's snowfall.