Geomagnetic storms are temporary disturbances of Earth's magnetosphere. They are caused by solar wind shock waves or clouds of magnetic field interacting with the Earth's magnetic field. A severe geomagnetic storm could potentially shut down power grids on a continental scale for months.[1]

Further reading

Roodman, David (2015a) Geomagnetic storms: using extreme value theory to gauge the risk, Open Philanthropy, July 13.

Roodman, David (2015b) Geomagnetic storms: an introduction to the risk, Open Philanthropy, June 29....

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