On May 15, 2018, Holborn’s Dan Zitelli presented at the 2018 RMS Exceedance conference in Miami, Florida.
The theme of Dan’s discussion was “How do you Calibrate a Cat Model to a Changing Climate?” By taking on this topic, Mr. Zitelli challenged his fellow cat modelers to think of the implications of a changing environment when modeling risk.
Highlighting factors such as CO2 levels and the limitations of NOAA’s HURDAT data in modeling, the discussion examined various factors to consider when modeling exposure to hurricane. HURDAT’s record precedes the Civil War and, while it is not a perfect database, it is the foundation of all hurricane models. Scientists believe there is missing data, due to lack of technology or human observation in the early part of the record. Only 29% of the data is post-satellite imagery, as such there remains subjectivity in analyzing long-term trends.
Mr. Zitelli spent time discussing the role Earth’s ocean currents and aerosols may also play in the Atlantic Multi-Decadal Variation. Human made aerosols from industrial practices, as
well as natural pollutants, are transported around the globe from their sources by interacting with weather systems, scattering and absorbing solar and terrestrial radiation, and modifying cloud
properties. In general, aerosols have a cooling effect on our environment and lead to a higher number but smaller water droplets in clouds, which cause droughts and, consequently, larger catastrophic downpours.
As to whether climate change plays a direct role in the frequency and intensity of hurricanes is still up for discussion. The science is still being discovered and factors affecting hurricane development are varied – some we may not understand, and many are yet to be incorporated into our cat models.