Hurricane Melissa: impact of climate change

University of Reading climate experts comment on the impact climate change is having on Category 5 Hurricane Melissa, set to hit Jamaica.

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Professor Hannah Cloke said: “Climate change is having an impact on the strength of this storm. Hurricane Melissa is fuelled by warmer-than-usual ocean waters, bringing enormous volumes of rain. While the frequency of hurricanes may go down, we know these stronger storms will become more dominant and bring intense rainfall. Rising sea levels mean more coastal communities will be at risk from storm surges and must prepare for floods and landslides.

“Melissa has been a strange hurricane, hanging around in the Atlantic and getting stronger in bursts. These rapid intensifications will also become more common with climate change. This is not a hypothetical scenario to be imagined. This is a real and deadly storm.

“This is one of those worst-case scenarios that you prepare for but desperately hope never happens. The whole country will have a deep and permanent scar from this beast of a storm. It will be a long and exhausting recovery for those affected.”

Dr Helen Hooker said: “Melissa has become one of the most intense Category 5 hurricanes ever recorded, with wind speeds estimated at over 200 mph as it approaches landfall in Jamaica.

“The rapid strengthening of Melissa is fuelled by unusually warm sea temperatures, which are close to record highs for this late in the season. Climate change has contributed extra heat to the atmosphere, absorbed by the oceans, creating ideal conditions for hurricanes to carry more rainfall.

“Melissa is moving slowly across Jamaica, meaning extreme and prolonged rainfall will likely cause widespread impacts from flooding and landslides, affecting areas far from the main core or eye of the storm.”

Prof Chris Holloway, Professor in Convection, University of Reading, said: "The sea surface temperatures in the central Caribbean have been about 1-2 degrees Celsius warmer than average over the last month, so this is consistent with climate change contributing to the threats posed by Hurricane Melissa.  Climate change likely increases the probability of very intense storms like this one because of warmer ocean temperatures, and there is increasing evidence that it leads to more rapid intensification on average as well, which was seen for this storm.  Climate change also leads to more water vapour in the atmosphere, which increases the potential for severe rainfall in these storms.  Lastly, sea levels are rising and will continue to rise with climate change, meaning that storm surge (coastal flooding) will be increasingly damaging for any given coastal location."

Dr Akshay Deoras said: “Warm oceans are a key ingredient for strong hurricanes. The part of the Atlantic where Hurricane Melissa is churning is like a boiler that has been left on for too long. Ocean waters are around 30 °C, two to three degrees above normal, and the warmth runs deep. Climate change has warmed the oceans, giving them more energy to fuel storms like Melissa than they would have had a few decades ago. This means that if Melissa had occurred decades ago over cooler oceans, she would not have been able to intensify so rapidly or sustain her strength.

“Developing a hurricane is like teamwork between the atmosphere and the ocean, so ocean warmth alone is not enough. The atmosphere also needs to be in a conducive state for a cyclone to intensify. Hurricanes require good ventilation, allowing heat and moisture to rise freely. For Melissa, we have a perfect combination: a very warm ocean below and an atmosphere acting like a well-ventilated chimney, helping the storm strengthen.”