Rare events

One way of judging which events are extreme involves selecting events that exceed a certain threshold of intensity (or frequency, or impact, etc., not shown). This threshold might select events lying above a certain percentile or beyond a certain number of standard deviations above average. In the field of extreme event attribution, climate models then process the climate characteristics underlying the selected events for comparison to models of climates in which man-made climate drivers are excluded.

Rare or extreme events are events that occur with low frequency, and often refers to infrequent events that have a widespread effect and which might destabilize systems (for example, stock markets, ocean wave intensity or optical fibers or society). Rare events encompass natural phenomena (major earthquakes, tsunamis, hurricanes, floods, asteroid impacts, solar flares, etc.), anthropogenic hazards (warfare and related forms of violent conflict, acts of terrorism, industrial accidents, financial and commodity market crashes, etc.), as well as phenomena for which natural and anthropogenic factors interact in complex ways (epidemic disease spread, global warming-related changes in climate and weather, etc.).