Sulfur-isotope anomalies recorded in Antarctic ice cores as a potential proxy for tracing past ozone layer depletion events

Journal article

Changes in the cosmic-ray background of the Earth can impact the ozone layer. High-energy cosmic events [e.g. supernova (SN)] or rapid changes in the Earth's magnetic field [e.g. geomagnetic Excursion (GE)] can lead to a cascade of cosmic rays. Ensuing chemical reactions can then cause thinning/destruction of the ozone layer-leading to enhanced penetration of harmful ultraviolet (UV) radiation toward the Earth's surface. However, observational evidence for such UV "windows" is still lacking. Here, we conduct a pilot study and investigate this notion during two well-known events: the multiple SN event (≈10 kBP) and the Laschamp GE event (≈41 kBP). We hypothesize that ice-core-Δ³³S records-originally used as volcanic fingerprints-can reveal UV-induced background-tropospheric-photochemical imprints during such events. Indeed, we find nonvolcanic S-isotopic anomalies (Δ³³S ≠ 0‰) in background Antarctic ice-core sulfate during GE/SN periods, thereby confirming our hypothesis. This suggests that ice-core-Δ³³S records can serve as a proxy for past ozone-layer-depletion events.

Authors: Dasari, S; Paris, G; Charreau, J; Savarino, J

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: PNAS Nexus
• Volume: 1
• Issue: 4
• Article number: pgac170
• Publication date: 2022-08-30
• Acceptance date: 2022-08-23
• DOI: 10.1093/pnasnexus/pgac170
• EISSN: 2752-6542
• Pmid: 36714879
• Language: English
• Keywords: Δ33S; cosmic-ray background; UV radiation; sulfur mass-independent fractionation (S-MIF)