Tuesday, September 2, 2008

Rising sea could cause huge losses on Cape Town's coastline

Private property losses caused by rising sea levels induced by climate change are estimated to amount to between R3.2-billion to R44.5 billion around the 307 kilometres of Cape Town's coastline over the next 25 years.

This is according to a report commissioned by the City of Cape Town. The report, released in early August, is the latest in a four-phase study commissioned by the City to examine the implications of sea-level rise. Two previous reports were released in May and modelled the extent of sea-level rise, but the latest report backs this up with the hard costs that are expected to be incurred.

It notes that the Cape's renowned sea storms have not slowed development, with residential and commercial development doubling between 1985 and 2005 and much of this taking place along the coast.

Sea-level rise would show some of this to have been "imprudent and necessitate a review of both the location and the nature of the City of Cape Town's growth".

The third report draws on three scenarios developed in previous phases of the study.

Scenario one is the "present day worst case scenario". It would involve a 2.5 metre increase in sheltered environments, a 4.5 metre increase in exposed environments and a 6.5 metre increase in very exposed environments. It has a 95% chance of happening in the next 25 years and would see 25.1 square kilometres covered by the sea, but only for a short period.

Scenario two, the "likely prevailing scenario" in 10 years, would involve a 4.5 metre rise and lead to 60.9 square kilometres being covered, also for a short period.

The most catastrophic scenario is the third one, which would see a 6.5 metre sea-level rise linked to the melting of the Greenland and West Antarctic ice shelves. This would permanently inundate 95 square kilometres of land. The study assumes a 20% chance of this occurring in the next 25 years.

Dealing with property, the study forecasts that with sea-level rise the average value of real estate will come down and estimates private property loses at R3.2 billion, R19.5 billion and R44.5 billion respectively for the three scenarios.

The report says coastal locations such as Blaauwberg, Llandudno, Hout Bay, Kommetjie, Glencairn and Strand have been at the forefront of booming development, but not all of this has been in accordance with environmental legislation.

Further implications with regards to property were an increase in property insurance costs for residents, with some property no longer being insurable. "Outmigration" would also affect the rates base of the city. By Patrick Burnett

Click here to read the reports:
Phase 3 - A Sea-Level Rise Risk Assessment for the City of Cape Town - Anton Cartwright

Phase 4 - Sea-Level Rise Adaptation and Risk Mitigation Measures of The City of Cape Town