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Scientists comment on Hurricane Melissa in Jamaica.
Dr Emily Vosper, Senior Research Associate in Climate Extremes, University of Bristol, said:
“Hurricane Melissa represents one of the strongest hurricanes to hit Jamaica in living memory, the slow-moving nature of Melissa, known as a stalling, makes it particularly hazardous. Moving at around 5 km per hour, Jamaica will be exposed to high levels of rainfall for a prolonged period of time increasing the risk of severe flooding.
“In the Caribbean, severe rainfall hurricanes, such as Hurricane Maria which hit Puerto Rico in 2017, are twice as likely to occur1 in the 2oC warmer world compared to a 1.5oC world. This is driven by the increased water holding capacity of the atmosphere by a rate of 7% per 1oC of warming. This relation is known as the Clausius-Clapeyron effect and is observed in extreme rainfall2. Hurricanes such as Melissa will therefore carry more rainfall3 than pre-industrial times as a result of climate change.
“The impact of climate change on the frequency of stalling hurricanes is less likely to have an impact. This study4 also found that the proportion of stalling hurricanes have not been shown to increase under climate change.”
“Not only does the distribution of population play a part in the region’s vulnerability, but the post-hurricane recovery time can be slow and roughly coincides with the average hurricane return time of approximately 5-10 years5. The recovery period can be even longer in the case of agriculture. The island of Grenada, for example, was once the world’s second largest exporter of nutmeg after Indonesia. Before hurricane Ivan struck in 2004, over 27% of the island’s population relied on nutmeg as an income source but in Ivan’s aftermath national production declined by more than 60%6. Unlike bananas, which can fully mature in less than 12 months with prompt replanting, nutmeg takes several years to recover from severe wind damage and even in 2009 the total production of nutmeg was still only 12% of pre-Ivan levels7. In terms of property, Grenada took over five years to recover8 as the vast majority of housing, public schools and health infrastructure was severely damaged.”
References:
1,4 https://iopscience.iop.org/article/10.1088/1748-9326/ab9794
2 https://link.springer.com/article/10.1007/s00382-006-0180-2
6 https://www.jstor.org/stable/41917603
7 https://www.ceintelligence.com/files/documents/GRD_Nutmeg_Strategy_2010-15.pdf
8 https://documents.worldbank.org/en/publication/documents-reports/documentdetail/538951468030331426
Dr Mireia Ginesta, Research Associate in Climate Damages Analysis at the Oxford Smith School of Enterprise and the Environment, said:
“We know that a warmer climate makes storms wetter and can make them stronger. When the atmosphere heats up, it can hold about 7 % more moisture for every degree of warming. This means that tropical cyclones now tend to produce heavier rainfall—and the Intergovernmental Panel on Climate Change (IPCC) has high confidence that both average and maximum rain rates in tropical storms and related systems have increased. Warmer oceans also provide more energy to storms, which can lead to stronger winds. On top of that, rising sea levels mean that storm surges are now starting from a higher baseline, making coastal flooding more dangerous. There is more uncertainty about other storm characteristics: how often they form, where they travel, or how long they last. The IPCC finds it likely that the share of very intense hurricanes (Category 3–5) has increased and that rapid intensification events are becoming more frequent. However, there is low confidence in any global trend in the total number of tropical storms.”
“For Hurricane Melissa we cannot yet say exactly how much climate change made it worse compared to natural variability. Rapid attribution studies, such as those by Climameter and World Weather Attribution, can provide early estimates, but a full scientific assessment takes longer and requires high-resolution data and detailed analysis. What we do know is that today’s warmer oceans, moister atmosphere, and higher sea levels influence every single storm by increasing its potential for heavier rain, stronger winds, and higher storm surge.”
Dr Akshay Deoras, Research Scientist at the National Centre for Atmospheric Science, University of Reading, 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.”
Dr Helen Hooker, Research Scientist, University of Reading, 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.”
Dr Michael Byrne, Reader in Climate Science, University of St Andrews, said:
“Right now, we cannot say for certain whether the intensity of Hurricane Melissa has been boosted by climate change – that detailed analysis will take time. But what we know for sure is that sea surface temperatures in the tropical Atlantic – the main development region for hurricanes – are now considerably warmer than the long-term average. These warmer surface temperatures, driven by climate change, are fuelling more intense hurricanes with more rainfall. As climate continues to warm, the world urgently needs to prepare for more and more of this kind of devastating weather event.”
Prof Hannah Cloke, Professor of Hydrology, University of Reading, 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.”
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.”
Prof Ralf Toumi, Director of the Grantham Institute, Imperial College London, said:
Why is Hurricane Melissa in particular so dangerous?
“The hurricane is unusually strong (Category 5 are rare), the slow movement means there is sustained wind speed and rainfall accumulation which increase the damage.
Is Jamaica particularly vulnerable to the impacts of hurricanes?
“The Caribbean is a known area of hurricane activity. Vulnerability increases with lower income and wealth.
Why is Hurricane Melissa so powerful? Has climate change made it stronger?
“The Caribbean sea surface temperature is even higher than normal and we know that climate change has contributed to this. We also know that warmer oceans will sustain stronger storms so there is direct connection to climate change.
Will hurricanes on this scale become more common in the future?
“We expect the frequency of these strongest storms to increase until we can stop the warming by reducing greenhouse gas emissions.
What kind of damage should emergency services be prepared to face in Jamaica as the hurricane makes landfall?
“Jamaica has had plenty of time and experience to prepare for this. Saving lives is the priority. I suspect when we see the total damage we will see the limits of preparedness that a country like Jamaica can afford.
Dr Leanne Archer, Research Associate in Climate Extremes, University of Bristol, said:
“There has been a perfect storm of conditions leading to the colossal strength of Hurricane Melissa: a warm ocean which has fueled its rapid intensification over the last few days, but it is also moving slowly, meaning more rain can fall whilst it moves across land. Most of these conditions have been supercharged by the extra heat in our oceans and atmosphere due to climate change. A warmer ocean means more energy; more strength; and more moisture in the warmer atmosphere means more rain can fall with a higher intensity.
“Jamaica experienced a devastating hurricane in 1903, but analysis of this event undertaken by climate scientists1 have shown that this same hurricane would have been more intense if it occurred now due to climate change. This suggests Hurricane Melissa could be the most devastating hurricane to ever hit Jamaica, which will have been amplified by our heating planet.
“Climate scientists are clear that a heating planet is likely to fuel hurricanes that lead to larger storm surges (due to higher sea levels); more intense rainfall; higher intensities and a larger number of events that become the most catastrophic (Category 4-5 events). Hurricane Melissa has all these aspects.”
References:
1 https://climatelabbook.substack.com/p/a-damaging-hurricane-in-a-warmer
Comments on flooding specifically:
“Although hurricanes are usually typified by their wind speed (of which Melissa is the most extreme on the scale), there is also a significant hazard posed by the slow-moving but immense rainfall expected to impact both mountainous and low-lying areas of Jamaica. This means that the risk of flooding and landslides is high. Where heavy rainfall causes flooding in the low-lying areas, there is also a risk of this inland flooding coinciding with coastal flooding caused by the expected storm surge (>4m). This compounding may lead to an amplification of the depth and extent of flooding in low-lying areas. It is useful to remember that despite our focus on wind when it comes to hurricanes, the rainfall and resultant flooding can be more deadly.”
Comments on climate impacts on small islands such as Jamaica:
“Hurricanes have the potential to significantly impact small islands such as Jamaica, as most of their populations and infrastructure are located along low-lying areas of the coast. This means the impacts of flooding from storm surge and extreme rainfall have a higher risk of impacting a large percentage of the population.
“Hurricane Melissa is yet another stark reminder that islands such as Jamaica face the brunt of accelerating extremes amplified by climate change, despite being among those who are the least responsible for the problem.”
Declared interests
Dr Emily Vosper: No conflicts of interest
Dr Mireia Ginesta: No interests to declare
Dr Akshay Deoras: No COIs
Dr Helen Hooker: No COIs
Dr Michael Byrne: None
Prof Hannah Cloke: None
Prof Chris Holloway: None
Prof Ralf Toumi: No declarations
Dr Leanne Archer: I don’t have any conflicts of interest.