Tuesday, August 5, 2008

Sea Flood - Parts of Cape in danger

Greenland and the West Antarctic may sound too far away to have any effect on the Western Cape, but new research shows that melting of ice shelves could put part of the Cape coastline under water within the next 25 years, with multibillion-rand repercussions.

The melting polar ice sheets could result in 95km2 of land around the Cape coastline - approximately 4 percent of the total land under the city's jurisdiction - ending up permanently under water.

At risk would be property, the tourism sector and infrastructure valued at more than R54-billion, the latest results in an ongoing city-commissioned study show.

Until recently this scenario was considered unlikely this century, but the new results say there is a 20 percent likelihood of it occurring in the next 25 years.

The risk of this scenario occurring is valued at R11-billion, a figure calculated by multiplying the probability of a hazard occurring by the cost of the damage caused.

The latest report containing the results of the third and fourth phases of an ongoing risk analysis assessment of sea-level rise was due to be discussed by the city's planning and environment portfolio committee today (Tuesday).

The city commissioned the study with the recognition that it must take a proactive approach to understanding the potential implications of climate change, as well as develop an adaptation strategy.

The latest research also quantified the potential economic impact to the city for two other likely scenarios, as a result of global climate change.

The first - the present day worst-case scenario - has a 95 percent chance of happening in the next 25 years with a potential economic impact of R5,2-billion.

The actual risk of this scenario occurring is valued at R4,9-billion.

With the increasing mean sea-level, and increasing intensity and frequency of storms, it is almost certain that the Cape Peninsula will be buffeted by at least one storm with this impact in the next 25 years.

During this time it is certain that the mean sea-level will be at least 35cm above the long-term mean, which could see 25.1km2 (1 percent of the city's total area) covered by the sea, albeit for a short time.

A second scenario, modelled on the first, assumes that this scenario would involve sea-level rise of 4.5m, which would see 60.9km2 (2 percent of the metro) covered by sea for a short period.

While researchers cannot be sure of exactly how the frequency with which these events will occur, it is assumed that this will be the prevailing scenario in 10 years' time, and has an 85 percent probability of occurring within the next 25 years.

It is estimated to have a potential economic impact to the city of R23,7-billion and carries actual risk valued at R20,2-billion.

But the third scenario in which there would be damage to property and infrastructure has a risk of actual occurrence of R11-billion. - Cape Argus

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