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The end-Permian mass extinction is the most severe known from the fossil record. The most likely cause is massive volcanic activity associated with the formation of the Permo-Triassic Siberian flood basalts. A proposed mechanism for extinction due to this volcanic activity is depletion of stratospheric ozone, leading to increased penetration of biologically damaging Solar ultraviolet-B (UVB) radiation to Earths surface. Previous work has modeled the atmospheric chemistry effects of volcanic emission at the end-Permian. Here we use those results as input for detailed radiative transfer simulations to investigate changes in surface-level Solar irradiance in the ultraviolet-B, ultraviolet-A and photosynthetically available (visible light) wave bands. We then evaluate the potential biological effects using biological weighting functions. In addition to changes in ozone column density we also include gaseous sulfur dioxide (SO2) and sulfate aerosols. Ours is the first such study to include these factors and we find they have a significant impact on transmission of Solar radiation through the atmosphere. Inclusion of SO2 and aerosols greatly reduces the transmission of radiation across the ultraviolet and visible wavelengths, with subsequent reduction in biological impacts by UVB. We conclude that claims of a UVB mechanism for this extinction are likely overstated.
Based on cosmological rates, it is probable that at least once in the last Gy the Earth has been irradiated by a gamma-ray burst in our Galaxy from within 2 kpc. Using a two-dimensional atmospheric model we have performed the first computation of the
Social-distancing to combat the COVID-19 pandemic has led to widespread reductions in air pollutant emissions. Quantifying these changes requires a business as usual counterfactual that accounts for the synoptic and seasonal variability of air pollut
Tropospheric ozone (O3) is a greenhouse gas which can absorb heat and make the weather even hotter during extreme heatwaves. Besides, it is an influential ground-level air pollutant which can severely damage the environment. Thus evaluating the impor
Climate models are critical tools for developing strategies to manage the risks posed by sea-level rise to coastal communities. While these models are necessary for understanding climate risks, there is a level of uncertainty inherent in each paramet
In modern surgery, a multitude of minimally intrusive operational techniques are used which are based on the punctual heating of target zones of human tissue via laser or radio-frequency currents. Traditionally, these processes are modeled by the bio