Comment: 'No clear evidence' that Cyclone Pam linked to climate change
Release Date 16 March 2015
Following the devastating tropical cyclone that hit the South Pacific island nation of Tuvalu, there have been claims that the severity of the storm - including some of the highest winds ever recorded in this part of the world - can be linked to climate change.
However, climate scientists at the University of Reading say that while climate change is likely to have an impact, there is currently 'no clear evidence' that this cyclone was caused by climate change.
Dr Nick Klingaman, climate scientist at the University of Reading, said:
"There is no clear evidence that climate change affected the formation or intensity of Cyclone Pam. The latest projections from climate models suggest that climate change will reduce the total number of tropical cyclones in the South Pacific, although the average intensity of the cyclones that do form may be stronger than at present.
"Coastal and island communities, such as those in Vanuatu, are also affected by sea-level rise, much of which is caused by global warming. Higher sea levels amplify the destructive storm surges that accompany tropical cyclones. In a warmer world, combination of rising sea levels and more-intense tropical cyclones may increase the damage caused by an individual cyclone, even if the overall number of cyclones decreases."
Dr Chris Holloway, a tropical storm expert at the University of Reading, said:
"Tropical Cyclone Pam had the strongest winds of any South Pacific tropical cyclone on record, and is tied for having the strongest winds of any Southern Hemisphere tropical cyclone on record. It has caused devastation across Vanuatu, largely because many buildings have been destroyed or severely damaged by the wind.
"The storm passed just to the east of the most populated island in Vanuatu, Efate, which contains the capital Port Vila: the winds felt on this western side of the storm were slightly weaker than the maximum storm winds because they were rotating in the opposite direction to the overall storm motion, and similarly storm surge was slightly lower on this side of the storm. Further south, the storm passed just to the west of the islands of Erromango and Tanna, which placed them in the most dangerous part of the storm with its highest winds and largest storm surge.
"It is impossible to say whether a specific extreme event like Pam was caused by climate change" - Dr Chris Holloway
"It is impossible to say whether a specific extreme event like Pam was caused by climate change, but we can estimate how the risk of some extreme events might have been increased or decreased by past climate change and how these risks might change in the future. In the case of South Pacific tropical cyclones, recent studies suggest that, although there may be slightly higher risks of the most intense cyclones, there are likely to be fewer cyclones overall, so that it is not clear whether the risks of a storm like Pam in this region have been changed or will be changed by climate change. On the other hand, globally it is most likely that the total number of tropical cyclones will decrease with climate change while the number of the most intense storms, like Pam, will increase.
"Climate change studies also predict that, for a given tropical cyclone, there will be more rainfall on average (leading to potentially more freshwater flooding). Furthermore, global sea levels are rising and will continue to rise, meaning that coastal regions facing a given tropical cyclone storm surge will be more vulnerable to coastal flooding."