Response to Comment on “Dying in the Sun: Direct evidence for elevated UV-B radiation at the end-Permian mass extinction”

Jardine, P.E.; Peng, H.; Marshall, J.E.A.; Lomax, B.H.; Bomfleur, B.; Kent, M.S.; Fraser, W.T.; Liu, F.

Abstract

Seddon and Zimmermann have raised questions about the evidence for increased UV-B flux across the end-Permian mass extinction (EPME) that was presented in our recent study, specifically regarding the measurement of UV-B–absorbing compound (UAC) levels in fossil pollen. We respond to these points, arguing that the com- parison of FTIR spectra of >250 million–year–old Permian fossil pollen with ~700-year-old subfossil pollen is not valid and that negligible nonrandom interference derived from water vapor fluctuations during data generation cannot coincidentally produce a substantial UAC peak during the EPME. Furthermore, we refute the suggestion that the measured aromatic peak at 1600 cm−1 could have been influenced by diagenetic products from other organic constituents of pollen. The most productive route forward will be to generate sporomorph geochemical data from additional Permian-Triassic boundary sections to test the results put forward in our study.