Major excursions in sulfur isotopes linked to permafrost change in Eurasia during the last 50,000 years

We identify a major sulfur isotope excursion in Eurasian faunal bone collagen from the last 50,000 years, here termed the Late Pleniglacial Sulfur Excursion. Our analysis suggests this is linked to changing permafrost conditions, presenting the utility of faunal collagen δ(34)S as a proxy for permafrost dynamics, a critical component of the global carbon cycle. Our findings complicate the use of archaeological faunal sulfur isotopes for mobility and palaeodietary studies.