b) magnitude of hazard events

Each hazard event type is measured on its respective magnitude scales – for example, earthquakes on the Ritcher magnitude scale and tropical cyclones on the Saffir-Simpson hurricane wind scale. However, these scales do not allow comparisons between the different types of climate hazard events. We thus adopt the description of magnitude via the probability of occurrence of hazard events, also known as return periods. To obtain return periods, statistical estimates are first calculated for a range of all possible hazard events based on all available historical observations of a hazard event. If a particular hazard event value has a 1 per cent frequency of occurrence, it has a one in a hundred probability of occurrence at any given year and is hence known as the 100-year return period (Lindsey, 2016). The same logic applies to 50-year and 30-year return periods, representing a 2 per cent and a 3.33 per cent probability of occurrence, respectively.

_{Lindsey, R. (2016, December 15). Extreme event attribution: The climate versus weather blame game. Climate.gov. https://www.climate.gov/news-features/understanding-climate/extreme-event-attribution-climate-versus-weather-blame-game}