Hurricane Irma: why have there been so many destructive hurricanes and will there be more in the future? We asked the experts
telegraph.co.uk
excerpt:
What is causing these large hurricanes?
Julian Heming, the Met Office's tropical prediction scientist, told The Telegraph about the reasons Irma is such a large hurricane.
"Irma is a powerful hurricane because all the characteristics required to produce an intense hurricane in the Atlantic are coinciding:
- Sea surface temperatures under Irma are 1 to 1.5°C higher than the average for this time of year providing abundant moisture and warmth.
- The wind shear (change in wind with height) is low, meaning air can flow in up and out of the hurricane very efficiently, thus promoting intensification.
- There are no drying influences at present, such as pockets of Saharan dust which sometimes drift out over the Atlantic.
- Irma is moving fast enough to prevent cool water up-welled under the hurricane from having any impact on the continued feed of warm, moist air into the hurricane.
- Up until now there has been no interaction with large land masses that might disrupt intensification due to cutting off the moisture supply."
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Professor Myles Allen, Professor of Geosystem Science at the University of Oxford, said he believes this is almost definitely due to climate change.
He explained:“As yet another hurricane barrels into the Caribbean, with extreme precipitation and the impacts of storm surges both exacerbated by past greenhouse gas emissions, we must begin to ask ‘how long can we expect taxpayers and those in the path of the storms to foot the entire bill for the impacts of climate change?’
“In a paper published today in the journal Climatic Change, we show that nearly 30% of global sea level rise from 1880 to 2010 can be traced to products sold by just 90 large corporations. We need to start a conversation about whether it makes sense to exempt companies selling products that cause greenhouse gas emissions from all liability for the consequences of their use. As we found in 2008, giving companies unlimited license to make private profits while society underwrites the risk ends badly for everyone.”
Is it likely to happen more frequently in the future? The Met Office said it is uncertain whether this will happen more frequently, and that models give conflicting answers.
Mr Heming said: "There is much debate about the influence of climate change on hurricanes in the Atlantic. The latest research suggests that there may be an increase in tropical cyclone intensity in the future, under continued global warming. However, the models also indicate that tropical cyclone frequency will either remain unchanged or decrease."
Dr Allan predicted that warm coastal areas can expect more of these in the future, due to climate change.
He said: "There will be a continued threat to warm, tropical coasts from these events in the future. While there is not clear evidence to suggest an increase in the frequency of all tropical cyclones in the future, warming of the planet will generate more intense rainfall, stronger winds and more massive storm surges when intense tropical cyclones form and it is expected that there will be more super-charged tropical cyclones or Hurricanes as the planet continues to heat up."
Dr James Baldini, Reader in Earth Sciences at Durham University, said these hurricanes could give us a worrying glimpse into the future of weather.
He said: “Just like one blizzard does not discount the reality of global warming, one extremely powerful hurricane does not define a trend towards more powerful storms. However, Hurricane Irma and Hurricane Harvey fit within the long-term trend toward fewer but increasingly powerful hurricanes, a direct result of rising North Atlantic sea surface temperatures under global warming. It is worrying to consider that unless greenhouse gas emissions are actively curbed, these types of storms may represent the new ‘normal’ in the future.”
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