Abstract
Ozone in Earth's atmosphere is known to have a radiative forcing effect on climate. Motivated by geochemical evidence for one or more nearby supernovae about 2.6 million years ago, we have investigated the question of whether a supernova at about 50 pc could cause a change in Earth's climate through its impact on atmospheric ozone concentrations. We used the "Planet Simulator" (PlaSim) intermediate-complexity climate model with prescribed ozone profiles taken from existing atmospheric chemistry modeling. We found that the effect on globally averaged surface temperature is small, but localized changes are larger and differences in atmospheric circulation and precipitation patterns could have regional impacts.
Highlights
Discovery of live 60Fe in ocean sediments at around 2.6 million years ago has established the relatively nearby explosion of one or more core-collapse supernovae (SNe) within a range of 50–100 pc [1,2,3,4,5,6,7]
Past work investigating the impact of astrophysical ionizing radiation events, including supernovae [9,12,13,33,34,35], gamma-ray bursts [10,11,36,37,38,39,40,41,42], and extreme solar storms [21,22,43], has primarily focused on depletion of stratospheric ozone and the effects of subsequent increase in solar UV irradiance on the ground and in the upper ocean
Some consideration has been given to other effects such as increased nitrate deposition [44,45], damaging ground-level ozone [46], increased lightning and wildfire [8], and the possibility of climate change following a drawdown of CO2 [47]
Summary
Discovery of live 60Fe in ocean sediments at around 2.6 million years ago (with a weaker signal about 8 million years ago) has established the relatively nearby explosion of one or more core-collapse supernovae (SNe) within a range of 50–100 pc [1,2,3,4,5,6,7]. At 50 pc, changes in UV irradiance and ground-level muon dose could be significant for some organisms [12,14] Another potential impact of changes in atmospheric O3 concentrations not previously explored is the effect on Earth’s climate. Previous radiative transfer modeling for the 50 pc case found small change in surface-level visible light irradiance due to changes in O3 [14], but that work was not able to evaluate the potential for changes in Earth’s climate. We investigate this possibility using a global climate model of intermediate complexity with O3 profiles from previous modeling [12]
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