Potential links between astrophysical sources, such as Gamma Ray Bursts (GRBs) and Super-novae (SN), and mass extinction events on Earth are of interest in the historical trajectory of life on our planet. There are strong arguments to suggest that these astrophysical sources can have several destructive effects, including depletion of atmospheric ozone and an increase in the radiation dose received by living organisms. Recent atmospheric simulations have shown that the fluence from a typical GRB at a distance of ∼2 kpc has the potential to deplete up to 38% of global atmospheric ozone, with as much as 74% localised depletion. In this work, it is hypothesised that the annihilation of Weakly Interacting Massive Particles (WIMPs) in the core of a clump of dark matter that passes through our solar system could be the source of a gamma ray fluence at the surface of the Earth that is of a similar magnitude to nearby GRBs. It was found that extremely dense clumps of dark matter, so-called Ultra-compact Minihalos, can produce a much larger fluence, potentially enhancing this effect. The implications of this would be a large flux of solar UV-B radiation able to penetrate the atmosphere, leading to widespread cancer formation and DNA damage, as well as significant changes to climate. These effects are compatible with extinction patterns found from the Late Ordovician extinction event that occurred ∼443 My ago.