Solar flares/CME dangers to life?
Abrevaya et al. (2020) in &quot;The UV surface habitability of Proxima b: first experiments revealing probable life survival to stellar flares&quot; (abstract, PDF) say:
&quot;Our results show the impact that a typical flare and a superflare would have on life: when microorganisms receive very high fluences of UVC, such as those expected to reach the surface of Proxima b after a typical flare or a superflare, a fraction of the population is able to survive. Our study suggests that life could cope with highly UV irradiated environments in exoplanets under conditions that cannot be found on Earth. &quot;
That suggests that total-extinction conditions aren't found on Earth, either.  The paper has a lot more detail of their assumptions and modeling, but that's my quick takeaway from the abstract.