Atmospheric & Climate Change

With its driving role for many hazards our atmospheric research, incorporating analysis of the impacts of climate change on extreme events, is a cornerstone of the WRN Core Research Programme.

The atmospheric programme is led by our WRN partners at Walker Institute, Reading, NCAR, Colorado, Exeter and SEA Australia and integrates with many of the wider Network membership.

At a macro-scale the programme is focused on the harnessing of the latest generation of higher resolution General Circulation Models (GCMs) of global climate, downscaled sufficiently to develop an understanding of current and future weather at local and regional scales.

The WRN believes that GCMs hold the key to gaining greater confidence in identifying future locations and levels of extreme events. The successful integration of GCM outputs into insurance-related catastrophe risk models offers the possibility of a major leap forward in catastrophe modelling capabilities.

The growing unification of climate modelling and weather forecasting communities around common models and approaches also offer two important areas of research for the WRN:

• Global Climate Teleconnections. Like "ENSO", understanding how climate events in one area may have correlated patterns elsewhere at different times is an important focus for the international insurance industry. Such work lies at the heart of effective diversification of global portfolios. Failure to understand these teleconnections can lead to unexpected concentrations of risk, even when portfolios are continents apart.
  
• Seasonal Forecasting. Developments in GCMs and weather forecasting are on the cusp of developing credible estimates for relative risk levels from 3 months to 18 months ahead. Even limited seasonal loadings of longer term statistical norms with moderate levels of confidence offer significant opportunities for insurers to heighten protection when necessary and allocate capital efficiently.

The atmospheric programme also examines key weather systems that drive extreme events. Research includes:

• The development of new tropical cyclone event sets for the Pacific and North Atlantic derived from GCMs rather than historical statistics. This include important work on cyclone genesis, tracks and storm intensities.
  
• Detailed understanding of the internal physics of cyclones to better understand wind speed and system strength and integrity.
  
• Estimating the hazard footprint of land-falling tropical cyclones including wind, storm surge and rainfall.

Beyond the tropics our work centres on cyclone systems especially in the North Atlantic and Europe:

• Storm Tracks. We combine statistical analysis and numerical modelling approaches to obtain greater confidence on the location, intensity and rainfall associated with jet streams and frontal systems in the North Atlantic. Small changes in prevailing tracks have significant influence on storm impacts at local and regional scales.
  
• Clustering of Storms. Loss events are not evenly spaced through time and research confirms that storms are not necessarily discrete weather events independent of one another. The annual nature of insurance and reinsurance contracts highlights the relevance of this area of work. Research focuses on understanding the extent of clustering and the probabilities of secondary and tertiary events.
  
• Hail Modelling. A significant concern, especially to agriculture and motor vehicles, hail is a challenging hazard to model due to its localised effects and infrequent occurrence. The WRN has undertaken hail modelling and analysis in Australia, South Africa, France and Germany.

Our atmospheric programme is closely integrated to our hydrological and flood modelling and provides a key input to these activities at regional and local scales.

Further information on the WRN Core Atmospheric Programme please contact Matthew Foote on matthew.foote@willis.com