The Heat Is Online

Lloyd's Research Arm Links Sea Surface Temperatures to Hurricane Activity

Insurance research paper confirms suspected hurricane activity link

Lloyd', Feb 13, 2008


According to new research by the Benfield UCL Hazard Research Centre (BUHRC), sea surface warming contributes significantly to increased Atlantic hurricane activity.

In the study  published in the scientific journal Nature  Professor Mark Saunders and Dr Adam Lea from BUHRC and based at the Department of Space and Climate Physics at University College London, reveal the current sensitivity of tropical Atlantic hurricane activity to sea surface warming is large, with a 0.5°C increase in sea surface temperature being associated with a 40% increase in activity and frequency.


They found that local sea surface warming was responsible for approximately 40% of the increase in Atlantic hurricane activity between 1996 and 2005, relative to the 1950-2000 average. Their research focuses on storms that account for 85-90% of the hurricanes that make landfall in the US.


The paper supports confirmation of the link between sea surface temperature and rising hurricane frequency, says Trevor Maynard, Manager of Emerging Risks in Lloyd's Exposure Management team.

This study is the latest in a long chain of research that quantifies the impact of sea temperatures on hurricane frequency, Maynard said.


BUHRC used a statistical model based on two environmental variables: local sea surface temperature; and an atmospheric wind field  which replicated 75-80% of the variance in tropical Atlantic hurricane activity between 1965 and 2005. By removing the influence of the winds from the model the team was able to assess the contribution of sea surface temperature.


Professor Saunders, who is also Head of Weather and Climate at BUHRC, said that the analysis does not attempt to identify whether greenhouse gas-induced warming contributed to the increase in water temperature. It is important that climate models are able to reproduce the observed relationship between hurricane activity and sea surface temperature, so improving their reliability to model how hurricane activity will be affected by climate change.


Other studies, particularly those of James B. Elsner at Florida State University, have demonstrated that man-made emissions have led to sea temperature warming.


Paul Budde, Executive Vice President and Head of the Product Development and Applied Research team at Benfield ReMetrics in the US, commented: Tropical cyclones are the most frequent cause of severe losses in the insurance industry. Research, such as that of Saunders and Lea, to quantify the relationship of specific environmental factors on hurricane activity, when combined with climate change models, will help the industry better understand what they might have to cope in the future.


Trevor Maynard says the findings are important because they give further weight to the argument that the level of hurricane risk has changed in the North Atlantic. It seems very likely to us that this background level of risk could translate into more land-falling storms, and pricing and capital calculations need to take into account insurers best estimates of the current level of risk.


In its 360 risk project, Lloyds stated that as climate change causes temperatures to rise further, insurers should be prepared for increased frequency of extreme storms not just in the Atlantic, but around the world. The industry may be on risk over a wider geographical area and the hurricane season may be longer according to the report.


BUHRC is predicting an active Atlantic hurricane season in 2008 with Atlantic basin and US land-falling tropical cyclone activity at 50% above the 1950-2007 norm. US risk modeller Risk Management Solutions (RMS) believes the average risk of land-falling hurricanes in the Atlantic Basin for the next five years is around the same level as has been predicted for the past two years, which is significantly above the risk averaged over the long term.