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Extreme Solar Events: On the Probability of Another Carrington Event

Extreme space weather events, such as the Carrington event of 1859, are, by definition, rare. Because of this rarity, estimating their rates of occurrence, as well as the uncertainty associated with these estimates, is difficult. This is compounded by the fact that an event may be considered extreme with respect to one parameter, but not to another. In this talk, I review our best statistical estimates for the probability of another Carrington event (or worse) occurring within the next decade. This depends crucially on an assumption concerning how the events are distributed in severity. In particular, we consider: power-law (with/without cut-off), log-normal, and (stretched) exponential distributions. The results vary; however, we can be reasonably confident that the probability of another Carrington event occurring within the next 10 years is between 2-12%. This suggests that they are, at most, as likely to occur as other so-called “100-year” catastrophes. Unlike most other disasters, however, the societal consequences of another Carrington-like event will not likely be regional; they will be suffered globally.