Climate and Hurricane Risk

1. Climate and Hurricane Risk Dr. Dail Rowe Accurate Environmental Forecasting www.accufore.com

2. The Team • This presentation is based on the work of a team of scientists at Accurate Environmental Foresting, Inc. and Climatek, Inc: • AEF • Dr. Michael Dickinson • Dr. Dail Rowe • Climatek • Dr. James Elsner (Florida State University) • Dr. Thomas Jagger

3. Today’s Discussion • Climate changes hurricane risk. • Regional risk changes by more then 200% • Climate factors influencing hurricane activity: • El Niño – Southern Oscillation (ENSO) • North Atlantic Oscillation (NAO) • Atlantic Sea-surface Temperature (SST) • Scientists generally agree on overall Atlantic basin activity. • Recent innovations: • Regions at risk • Hurricane intensity • Translation from hazard to insured loss • Forecasting

4. El-Niño / Southern Oscillation (ENSO) El Niño(warm event) La Niño (cold event) Sea surface temperature patterns in the eastern tropical Pacific Ocean change global weather patterns.

5. http://hurricanes.noaa.gov ENSO Modulates Vertical Wind-shear Hurricanes derive their power by transporting water vapor from the ocean surface up a natural chimney to the upper atmosphere. Their strength relies on the existence of this chimney structure.

6. http://hurricanes.noaa.gov ENSO Modulates Vertical Wind-shear Weak wind-shear is conducive to hurricane development. La Niña = weak shear and more hurricanes

7. http://hurricanes.noaa.gov ENSO Modulates Vertical Wind-shear Strong wind-shear disrupts hurricane structure. El Niño = strong shear and fewer hurricanes

8. North Atlantic Oscillation (NAO) High NAO Low NAO Hurricanes that form in these conditions are more likely to travel westward towards the southern US. NAO determines the strength of the atmospheric circulation in the Atlantic basin and is calculated as the difference in sea level pressures between Reykjavik, Iceland and Gibraltar.

9. Atlantic Sea Surface Temperature Warmer ocean surface temperatures promote hurricane growth and development.

10. SST leads to decadal variability There is a clear multi-decadal signal in Atlantic Sea Surface Temperatures. Casual analysis of the hurricane record shows a clear link between SST and hurricane activity. Detrended May-June average SST anomalies

11. SST impact on hurricanes Cool Atlantic SST Warm Atlantic SST Major hurricanes tracks from 1951-1998 stratified by SST

12. Cold vs. Warm SST Regimes Major HurricanesU.S. LandfallsFlorida Landfalls Cold: 1900 - 1925:        32                           8                           2 Cold: 1970 - 1994:        38                           9                           2 1.4 / yr 1 / 3 yrs1 / 12.5 yrs Warm: 1926 - 1969:     115                        23                         12 2.6 / yrs                1 / 1.3 yrs             1 / 2.1 yrs Warm: 1995 - 2004:      38                           6                          4 3.8 / yrs                1 / 1.7 yrs             1 / 2.5 yrs

13. Probability in Climate of Interest Average Probability Index = Modeling of Climate Factors and Hurricane Activity • We employ a statistical modeling approach as in Elsner and Jagger (2004) andElsner and Bossak (2005) to relate climate factors and hurricane activity. • Based on 130 year climate and hurricane records • The Hurricane Climate Risk Index is a regional measure of the climate-conditioned annual hurricane probability relative to the averaged probability.

14. Consensus and Innovation • Most agree on projections of overall Atlantic Basin hurricane activity for the upcoming season. • Innovations are occurring • Regions at risk • Storm intensity • Forecasting • Translation from hazard to insured loss

15. Hurricane Index: 1938 Climate SSTNAOENSO  ENSO Trend Factors: 0.21    0.31      -0.65        -0.23 Category 1-5 Hurricanes Category 3-5 Hurricanes

16. Hurricane Index: 1989 Climate SSTNAOENSO  ENSO Trend Factors: 0.08    0.32      -0.73        0.36 Category 3-5 Hurricanes

17. Hurricane Index: 1994 Climate SSTNAOENSO  ENSO Trend Factors: -0.11    0.78      0.33        0.31 Category 3-5 Hurricanes

18. Hurricane Index: 2004 All hurricanes 2004 was moderately risky for hurricanes in general, but… SST: 0.31 NAO: -0.51 ENSO: 0.24 ENSO Trend: 0.58

19. Hurricane Index: 2004 All hurricanes 2004 was moderately risky for hurricanes in general, but… SST: 0.31 NAO: -0.51 ENSO: 0.24 ENSO Trend: 0.58 Cat 3.5-5 hurricanes Cat 4-5 hurricanes it was VERY risky for extreme events in the southeast US.

20. Climate Forecasts • ENSO and Atlantic SST forecasts have useful skill at lead times of at least 9 months. • Good Florida to Maine risk forecasts well in advance of the hurricane season. • Forecasts of summer NAO conditions are less skillful. • Forecasts of Gulf of Mexico activity improve just prior to the hurricane season.

21. Insured Loss and Climate • The climate induced changes in hurricane frequency and severity indicated by the Index can be used to modify the frequency and severity assumptions governing the creation of the synthetic events sets commonly used to probabilistically evaluate hurricane related insured risk. • AIR and AEF have recently integrated our Index technology with AIR’s hurricane catalog to produce forecasts of how climate variability will affect the probability of insured loss during the upcoming hurricane season.

22. Insured Loss and Climate Synthetic Hurricane Event Set Damage Assessment Insured Loss Estimation

23. Insured Loss and Climate Synthetic Hurricane Event Set Damage Assessment Insured Loss Estimation 18 39

24. Insured Loss and Climate Synthetic Hurricane Event Set Damage Assessment Insured Loss Estimation Climate induced changes in Loss Exceedance Curves 18 39

25. Conclusions • Climate variability modifies both the frequency and severity of hurricanes on a regional basis. • Regional changes of more then 200% • El Niño, the North Atlantic Oscillation, and Atlantic sea-surface temperature are all important factors • The AEF/AIR Climate Conditioned Hurricane Catalog permits users to evaluate the effect of climate variability on their hurricane related exposure.