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Environment
26 April 2019
Cyclone Kenneth has hit MozambiqueNASA
By Michael Le PageMozambique has been hit by one of the strongest hurricanes to ever make landfall on mainland Africa. Storms in the region appear to be growing stronger as a result of climate change.
So far only a few deaths as a result of the storm have been reported but the worse could yet be to come. Cyclone Kenneth is forecast to slow to a crawl and dump nearly a metre of rain in northern Mozambique in the next few days, which could lead to serious flooding and landslides.
Kenneth has struck just six weeks after another very powerful storm, Cyclone Idai, carved a trail of destruction through Mozambique, Malawi and Zimbabwe, killing more than 1000 people and causing more than £1.5 billion worth of damage. Fortunately, Kenneth has struck a more sparsely populated region and so should cause less devastation.
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“It’s official: Cyclone Kenneth is now the strongest storm to make landfall in recorded history in Mozambique – and in the entire African continent,” meteorologist Eric Holthaus claimed on Twitter.
However, Jennifer Fitchett of the University of Witswatersrand in South Africa told New Scientist that Cyclone Kenneth is tied with Cyclone Eline in 2000 in terms of wind speed at landfall. Nevertheless, her work shows that tropical cyclones in this region are growing stronger as a result of global warming.
“We’re always very cautious not pin one particular storm to climate change, but in terms of the pattern of Idai and now Kenneth, there’s this regional intensification of storms that we’re seeing quite clearly,” Fitchett says.
Cyclone Kenneth is unprecedented in several ways. Firstly, it is only the second Category 4 storm ever to strike Mozambique and together with Eline the strongest ever to hit mainland Africa, though the islands of Madagascar and the Seychelles have been hit by even stronger Category 5 storms.
Secondly, it struck just six weeks after Idai. Mozambique has never been hit by two storms of Category 2 strength or higher in the same year since satellite records began.
Kenneth also intensified very rapidly, in less than 24 hours, making it even more dangerous. The day before Kenneth struck, people were still being told it would be just a Category 1 storm, says Fitchett. “People go to bed and wake up to disaster.”
Hurricanes worldwide appear to be intensifying more rapidly as the planet warms, like Hurricane Michael last year.
Kenneth is also unusual in that it hit the far north of Mozambique, near the equator. Tropical cyclones don’t usually form near the equator because the Coriolis force is too weak to impart the spin they need to form.
“The further north you move, the less impact you have from Coriolis,” says Fitchett. “So then the rotation is primarily driven by extreme uplift, which requires very warm sea surface temperatures to induce.” And sea surface temperatures are getting warmer because of climate change.
Despite all this, Julian Heming of the UK Met Office, who studies tropical cyclones, is cautious about linking Idai and Kenneth to global warming. There’s a lot of variability from year to year and region to region, he says. Globally, though, the frequency of strong storms is expected to increase as the planet warms.
Heming agrees with Fitchett that Cyclone Kenneth is tied with Eline in terms of intensity. In the absence of direct measurements, wind speeds have to be estimated based on satellite data and there’s always a margin of error, so it may not be possible to say for sure which was stronger at landfall.
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