Coastal properties could be submerged

Several multimillion-rand holiday homes on the Kwa-Zulu-Natal coast are likely to be severely damaged or washed away in the coming decades unless expensive ocean defences are built to protect them from rising sea levels.

This is the warning from coastal planning expert Andrew Mather, who has drawn up dramatic visual illustrations of projected sea level rise on the North Coast.

The simulations of sea levels rising between 300mm and 1m by the turn of the century (2100) clearly show the vulnerability of numerous holiday flats in the Ballito area, and other large property blocks next to Willard Beach.

Some of these buildings also took a battering during the severe sea storm off the coast in March, 2007.

Mather, head of coastal policy projects for the eThekwini municipality, stressed that his simulations of sea level rise were based on preliminary modelling work. However, they illustrated that municipal planners and developers should be very cautious about building or authorising any further developments too close to the beachfront.

He was speaking at a climate change summit in Ballito last week organised by the Ilembe district municipality.

Mather said it was extremely difficult to estimate the extent of sea level rise over the coming decades because of scientific uncertainties about the exact rate of sea level changes caused by global warming and climate change.

The UN expert group, the Intergovernmental Panel on Climate Change (IPCC), had estimated a very high probability of a global rise in sea level of between 170mm and 590mm by the year 2100, although more recent work suggested that levels could rise by a further 700mm because of faster-than-expected melting of polar ice.

Mather said German planners were now assuming a 1m rise, while Dutch planners were assuming a 1.4m rise by the turn of the century.

He said the rise in sea level was unlikely to be uniform across the world, noting that measurements along South Africa's coastline over the past 33 years were significantly different.

For example, the average annual rise in sea level along the west coast was 1.87mm, compared with 1.48mm along the southern Cape coast and 2.74mm on the east coast.

Mather said an annual rise of 2.7mm seemed like a very small figure, but became much more significant on those sections of coast with very flat beach profiles.

As a result, he had drawn up preliminary simulations for KwaZulu-Natal's north coast ranging between 300mm and the more extreme calculation of 1m.

He told The Mercury that his "best guess" was that city planners in KwaZulu-Natal should work on a sea level rise of about 600mm by 2100.

He told delegates that previous modelling work for the Durban beachfront area indicated similar risks, including the likelihood of severe damage to the Durban Central Sewage Works at the base of the Bluff.

Faced with these threats, planners had the choice of relocating exposed infrastructure and buildings further inland, or to try to defend them by building expensive sea wall defences.

"But one thing is certain... We cannot defend the whole South African coast, because ultimately that would cost all of us a lot of money."

It was also understandable that no municipality or developer wished to spend money to prevent something which might never happen. This was why it was important to review the latest sea level rise projections every decade or two.

"But we also have to use the information we have, rather than leaving it on a shelf until the next disaster happens."

Professor Laurence Dube, of the SA Weather Services climate change section, told the summit that several low-lying and highly populated areas along the African coastline would become increasingly vulnerable to rising sea levels by the year 2100.

This was largely the result of the increasing level of greenhouse gases heating up the Earth's atmosphere, in much the same way as the inside of a car heated up rapidly on a hot summer day when the windows were kept closed.

The volume of carbon dioxide emitted from human activities had risen from about 29 giga tons in 1970 to about 49 giga tons in 2004.

Ilembe district mayor Sibusiso Mdabe said that because of the disappointing lack of global action from world leaders in Copenhagen last year, it was now up to indivi-dual governments, community groups and individuals to "make a difference" on their own.

"Each and every one of us must begin to ask ourselves a sensible question: What am I doing to save the Earth from climate change?"

  • This article was originally published on page 1 of The Mercury on August 09, 2010

Article by: Tony Carnie - www.themercury.co.za