WHEN THE CAPE PENINSULA WAS AN ISLAND

LAST week’s article was about an aborted Dutch East India Company (VOC) plan to dig a canal between Table Bay and False Bay in the 1650s to prevent the Khoisan from “trespassing” on territory which the commercial powerhouse claimed for itself.

This wasn’t as bizarre as it sounds – the sandy flats between the Cape Peninsula and the rising ground on the horizon (which the Dutch called “the Mountains of Africa”) are proof that the area was once submerged.

According to geologists, sea levels around the coast were 25m higher about 5 million years ago, and scarcely changed during the next 3.5 million years. What is now the Cape Peninsula was then two mountainous islands separated by a channel which ran between Fish Hoek and Noordhoek.

Even more remarkable, sea levels during the last ice age, a mere 20 000 years ago, dropped an astonishing 125m, enabling our ancestors to walk across False Bay on dry land.

Now that sea levels are rising again, thanks to a cocktail of climatic variables which include thawing glaciers, melting ice caps, thinning sea ice and the thermal expansion of the oceans due to global warming, what can we expect?

Some of the best brains in climate science have done the calculations but no one is quite sure. Predictions range from a global average rise of 0.6m to 2.7m by the end of the century, innocent sounding figures that will spell disaster for hundreds of millions of people living in lowlying areas around the world.

At first, threatened communities will attempt to keep the encroaching sea at bay with sandbags, levees and dykes which may work well enough during calm periods, but the sea is seldom tranquil.

It pounds coastlines with waves, high tides, storm surges, hurricanes and cyclones, and its relentless scouring action erodes headlands, cliffs and man-made barriers.

Meanwhile, the climate change bus is moving and there is little chance of us jumping off. Temperatures and sea levels will continue to rise decade by decade, threatening the existence of life as we know it in the centuries to come.

For those who would like to see what the Peninsula looked like when the Cape Flats was last submerged 1.5 million years ago, there’s a fascinating interactive internet site at Flood Maps – Firetree.net

Scroll down to Cape Town, enlarge the map and choose a 20m flood setting and you will see dozens of submerged or waterlogged suburbs, ranging from Green Point, the Waterfront, Table View and Milnerton to Maitland, Langa, Gleemoor, Ottery, Grassy Park, Lavender Hill, and Marina Da Gama.

Bear in mind that a sea-level rise of such a magnitude wouldn’t occur in your lifetime.

However, it might be on the cards in the future.

Predictions range from a global average rise of 0.6m to 2.7m by the end of the century, innocent sounding figures that will spell disaster for hundreds of millions of people living in low-lying areas around the world