Earth Today | Extreme hurricanes forecast the future

FROM HURRICANES Irma and Maria in 2017 to Hurricane Dorian this year – all of which caused devastation in the Caribbean with their Category 5 strength – the future of a region marked by unprecedented climate is being foretold.

Dr Tannecia Stephenson, head of the Physics Department and the Climate Studies Research Group at the University of the West Indies (UWI), made this observation recently.

“Irma, Maria and Dorian hint at what the future hurricane will be like,” she said, speaking last Thursday at the UWI Science for Today public lecture series, held on the topic ‘Abandon ship? A science take on disaster risk reduction and small island resilience in light of Dorian’.

According to the physicist, the hurricanes’ behaviour line up with Intergovernmental Panel on Climate Change projections for future hurricanes, including increases in rainfall rates, increase in maximum wind speeds, rapid intensification and maintenance of strength.

Irma and Dorian, for example, had wind speeds of up to 185 miles per hour, tying as the second-strongest Atlantic hurricanes by wind speed, only after Hurricane Allen in 1980. Maria, for its part, packed maximum winds of 175 miles per hour.

AFTERMATH

All of them held horrendous consequences for sections of the region, including countries such as The Bahamas and Dominica that suffered death and hundreds of millions of dollars in loss and damage.

Stephenson went on to paint the picture of Hurricanes Irma and Maria that dumped inches of rainfall over Cuba and Puerto Rico, respectively; and with sustained wind speeds of 185 miles per hour for 37 hours in the case of Irma, making it the only tropical cyclone worldwide to have wind speeds for that long. Hurricane Maria had explosive strengthening with 70 miles per hour maximum wind intensification in 18 hours.

As for Dorian, it moved through The Bahamas for 27 hours at Category 5 strength, bringing a storm tide of 6.1 to 7.6 metres and dumping 0.91 metres of rain over the country. Dorian now has the reputation of having gone through not just one but two rapid intensifications, that is, a greater than 35 miles per hour increase in wind speed in less than 24 hours. It also broke the record for the strongest storm so far north in the Atlantic east of Florida.

Put into context, Stephenson said of the 36 recorded Category 5 hurricanes since 1924 in the Atlantic, Caribbean Sea and the Golf of Mexico, 14 or 39 per cent have occurred since 2000.

“Only seven seasons – 1932, 1933, 1961, 2005, 2007, 2017 and 2019 – have more than one Category 5. Only in 2007 and 2017 did more than one make landfall at Category 5 strength. 2016 to 2019 are the longest sequence of consecutive years which all featured at least one Category 5 hurricane,” she explained.

“A new normal? It may be too early to say, but the three hurricanes do provide further evidence of the emergence of an era marked by unfamiliarity; foretell a future marked by unprecedented climate, and notify us of the need for urgent action that ups the ante,” she added.