27 June 2005

Climate change in Africa gave rise to modern humans

Now experts fear that global warming linked to carbon emissions will have its worst impact on humanity's cradle. "Africa is the most vulnerable continent to climate change," said Jennifer Morgan, director of the Global Climate Change Programme at conservation group WWF.

"Most African livelihoods depend on rain-based agriculture so droughts and floods will have a serious impact on the workforce," she said, adding that the continent's extreme poverty reduced its ability to cope. Africa's plight will be high on the agenda of a Scottish summit of the Group of Eight industrialized nations next month which could herald increased aid flows to the region.

British Prime Minister Tony Blair has also made climate change a priority of Britain's year-long presidency of the G8.

Global warming is widely blamed on emissions of heat-trapping gases from cars, factories and power plants -- gases mostly spewed from the rich world.

"If leaders don't deal with climate change effectively they won't be doing all they can for Africa," said Morgan.

Climate change in Africa prodded mankind's distant ancestors along their evolutionary path as forests gave way to grasslands, forcing early humans into an open environment where it appears stone tools and long strides first developed.

But while most past changes in weather patterns were gradual -- giving our pre-historic ancestors a chance to adapt -- the pace of global warming today could overwhelm modern Africa.

The United Nations projects that temperatures may rise by 1.4-5.8 Celsius by the year 2100.

Desertification threatens to drive millions of Africans from their homes, said a recent international report drawing on the work of 1,360 scientists in 95 nations.

The problem is illustrated by gullies of eroded, barren earth scarring the shoreline of Lake Victoria, which borders Kenya, Uganda and Tanzania. The Kenya-based World Agroforestry Center says one of them, the Katuk-Odeyo gully, now extends to a remarkable 45 km (30 miles).

Global warming may already be a source of violence in central Nigeria, where nomadic cattle herders and peasant farmers have been locked in conflict over scarce land for decades as the desert creeps southwards.

Deforestation, dwindling water supplies and rising sea levels could spark mass migrations, provoking ethnic conflict.

"Regions that are already least secure in food production, like sub-Saharan Africa, stand to be worst affected by global warming as wet areas become wetter and dry areas become drier," says a recent global report on climate change.

Uganda's climate has become hotter and its rains more erratic in the last decade, researchers and the government say, posing a threat to its key coffee crop.

Rising sea temperatures are also among the threats seen to the coral reefs off Africa's lush east coast, the life-blood of poor coastal communities dependent upon fisheries and tourism.

And this tragedy of the weather is unfolding across the continent where climate change gave birth to modern humans.

The evidence for this is embedded in the Sterkfontein caves, 30 km (18 miles) northwest of Johannesburg, where hominid fossils dating back over 4 million years have been unearthed.

"There was a drying up of Africa around 2.5 million years ago ... There was a change from forest to grassland," said Dr. Ron Clarke, who heads excavations at Sterkfontein.

Intriguingly, it was in this period that the Sterkfontein fossil record reveals our ancestors first making stone tools.

"The change in climate may have forced us into an open environment with new challenges which meant we had to adapt by using tools. That of course is speculation," Clarke said.

Climate change would continue to steer humanity's path.

"About 130,000 ago, the climate switched ... briefly into a warmer, moister mode," write Chris Stringer and Robin McKie in their book "African Exodus: The Origins of Modern Humanity."

"The deserts began to retreat and the forests to expand again, a situation that probably led to prototype modern humans' first tentative steps out of Africa into the Middle East 120,000 years ago," they say.

The Sterkfontein Caves, surrounded by rolling farms, are again witness to environmental change -- this time man-made.

"The water table below the caves is dropping because it is being pumped out by local farmers," said Clarke. And water in the area will become more scarce if temperatures rise as fast as some fear.

Source: Reuters


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