Tropospheric Ozone During the Last Interglacial

• Published in: Geophysical Research Letters
• Main Authors: Yan, Yuzhen, Banerjee, Asmita, Murray, Lee T., Tie, Xin, Yeung, Laurence Y.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Antarctic; Antarc*
• Online Access: https://hdl.handle.net/1911/114256; https://doi.org/10.1029/2022GL101113

The history of tropospheric O3, an important atmospheric oxidant, is poorly constrained because of uncertainties in its historical budget and a dearth of independent records. Here, we estimate the mean tropospheric O3 burden during the Last Interglacial period (LIG; 115 to 130 thousand years ago) using a record of the clumped isotopic composition of O2 (i.e., Δ36 values) preserved in Antarctic ice. The measured LIG Δ36 value is 0.03 ± 0.02‰ (95% CI) higher than the late pre-industrial Holocene (PI; 1,590–1,850 CE) value and corresponds to a modeled 9% reduction in LIG tropospheric O3 burden (95% CI: 3%–15%), caused in part by a substantial reduction in biomass burning emissions during the LIG relative to the PI. These results are consistent with the hypothesis that late-Pleistocene megafaunal extinctions caused woody and grassy fuels to accumulate on land, leading to enhanced biomass burning in the preindustrial Holocene.