Extreme Solar Flare as a Catastrophic Risk

Space weather, or the disturbances of the plasma environment driven by the magnetic activities in the Sun in geospace, has become a potential source of disaster for modern society, which is increasingly dependent on its space infrastructure and large-scale power grids. Recently, independent pieces of evidence have been found that support the possibility of extremely intense space weather driven by a "superflare," a solar phenomenon that modern society has never experienced. This paper reviews state-of-art studies of superflares and their potential impacts.