Johannesburg - When it arrives it will announce itself with 200km/h winds, a wall of water four metres high and it will leave a trail of death.

This killer will be something South Africans have never seen before - a category five cyclone barrelling down the Mozambique Channel and making landfall as far south as Richards Bay in KwaZulu-Natal.

Not long ago the idea of such a powerful cyclone striking the coast of South Africa was thought to be impossible but now because of ocean warming brought on by climate change, modelling by a supercomputer has predicted that this could become a reality in the next couple of decades.

And the signs are already there. In a space of four years Mozambique has been hit by two powerful cyclones that killed upwards of 3 000 people. Thousands still remain missing. Cyclone Idai struck the Mozambican city of Beira at midnight on March 14, 2019.

No one is sure of the exact death toll, but as many as 1 500 died, making it one of the deadliest cyclones to hit Africa and the southern hemisphere. The residents of Beira faced a storm surge of water that witnesses said was between three and four metres high.

Cyclone Freddy this year made history when it became the longest lived cyclone lasting from February to March. In March the heavy rains caused by the cyclone caused landslides in Blantyre in Malawi, leaving at least 1 216 people dead in the landlocked country.

The problem is that science still has a lot to learn about cyclones in the south-eastern Indian Ocean, although recent climate modelling by the Lengau supercomputer at the Council for Scientific and Industrial Research in Cape Town has predicted the possibility that powerful cyclones are going to start heading south as far as Maputo.

Francois Engelbrecht, Professor of Climatology at the University of Witwatersrand and Director of the Global Change Institute, warned: “The risk is not limited to Maputo. It could also propagate westwards into the Limpopo River valley between South Africa and Zimbabwe. Such systems can even move further into Mpumalanga. Richards Bay is also an absolute possibility.”

In an effort to learn more about these cyclones and save lives in the future, an international project was recently launched that aims to limit the impact of these deadly weather systems in southern Africa and Madagascar. Called Resilience and Preparedness to Tropical Cyclones across Southern Africa (Represa), the project brings together universities and organisations from several countries and includes social and physical scientists, national and international hydrological and meteorological services.

The R110 million project will be co-led by Wits, the University of Bristol in the UK, and Eduardo Mondlane University in Mozambique.

“A key question that this project will be trying to ask is how will climate change change the attributes of the tropical cyclones that impact on the southern African region?” Engelbrecht said.

The researchers will also be harnessing the computing power of other supercomputers in Europe to help refine climate modelling.

Research will also go into developing early warning systems that will enable authorities to track cyclones and predict their pathways of the coming days.

This information will help in predicting which communities will need to be evacuated out of the path of these cyclones.

Through the study of hydrology the researchers also want to identify areas at risk from the flooding caused by the excessive rainfall these cyclones also bring. By understanding the damage these cyclones will cause, infrastructure can be designed and built to protect cities and towns in the future.

While this new project could provide the early warning systems that could save lives, the prospect of a category five cyclone striking along the northern KwaZulu-Natal coast remains frightening.

Such a disaster could kill thousands and leave hundreds of thousands of citizens displaced and homeless. It would also leave South Africa dealing with a mega disaster never seen before.

Marine geologist, Professor Andrew Green of the University of Kwazulu-Natal, said the country was definitely not capable of dealing with a disaster of such catastrophic proportions especially since Richards Bay and surrounding areas were built on reclaimed swamp land which was essentially one big coastal lake system, like a big lagoon.

“What the guys have done is that they’ve built closer and closer to the margins of the lagoon in areas that would naturally be wet and dry seasonally, so they've drained those and reclaimed it much like the Durban CBD.”

He said if there was suddenly a big tropical cyclone, it would not only result in a massive amount of rainfall but water would accumulate in low lying areas; add a storm surge to the mix and if there was a huge amount of increased sea surface elevation, coupled with the swells driven by the cyclone and "God forbid" a high tide, it could lead to a meteorological tsunami. He said this would be "incredibly aggressive and exceptionally destructive”.

“There’s no way that we would be currently prepared for it, not at all. We've built so much on low lying areas which should not have been built on. But we built on this in the sixties when people didn't really know and there were no proper environmental management schemes. So now there’s no going back and those are the areas that get exceptionally prone to major destruction.”

Green, who is not part of the project, said that while it's conceivable that it could recur in the Richards Bay area, the predicted timelines seem exceptionally rapid given that those category cyclones are not even striking southern Mozambique at the moment.

He said the latest information means that we would be faced with exceptionally rapid sea surface warming temperatures over the next two decades to get the kind of weather predicted by Wits.

The future prospects of a cyclone comes as KwaZulu Natal has been recently rocked by extreme weather that has been blamed on climate change. Over the past four years KwaZulu-Natal has been battered by a series of devastating floods, resulting in hundreds of deaths and billions of rands in infrastructure damage.

A week ago, a tornado followed by flooding resulted in devastating consequences for Durban residents who again lost their homes. At least seven people died and others are still missing.

Professor Tafadzwanashe Mabhaudhi, a lecturer in climate change at the University of KwaZulu-Natal, said as the weather patterns changed so too should our infrastructure development.

He said it was imperative to design climate resilient roads and buildings and homes should be built with the current conditions considered as factors.

While the South African Weather Service had excellent systems in place, and the government had disaster management plans, there were questions about whether citizens knew what to do in the case of an emergency. He said climate change literacy and numeracy were key to survival and the media and scientists played a critical role in getting the information to people. Indigenous knowledge also played a key role in determining which areas were safe and which were more vulnerable to climate change and its effects, he added.

A warming planet, scientists warn, is bringing change.

“We have had two cyclones in four years, we need to wake up and start preparing for tropical cyclones that are becoming more intense,” said Engelbrecht.

The Saturday Star