Extreme Space Weather: How Often Does It Occur? (Invited Presentation)

By many accounts 1859 was the year that society was first influenced by what is now called ‘space weather’. From the modern press viewpoint, the next extreme space weather event was reported as the 1989 Hydro-Quebec power outage. This apparent 130 year gap has led some to surmise that space weather events are extremely rare. In this presentation we will show strong evidence that extreme space weather is more frequent and has had stronger effects on society and engineered systems than is generally understood. Recent reports of a number of intervening, but less well-known events including those in 1872, 1921 and 1972 have surfaced that will add to our overall picture of the impacts of severe space weather. We will highlight several of these and discuss the surprising vulnerabilities to evolving technologies that these events have revealed. We believe additional investigations of historic non-English literature and trade journals in any language are a key to identifying other extreme events. These historical events need further analysis to create better benchmarks and scenario sets for for training and education space weather practitioners and for societal appreciation of severe space weather.