African apocalypse: The continent burning into a desert

'I am 70 years old now, and the temperatures are getting hotter and hotter as the years go by," says Habiba Hassan, standing in a field of ruined crops near her village of Beniday in Somalia.

The winters where she lives, 200 miles north-west of Mogadishu, used to be "very hot during the day and cold at night", she adds. But now "we have to sleep outside at night, it is so hot".

Somalia's harvest, brought in last month, is almost 30 per cent lower than normal, the result of the worst drought in at least 40 years. The UN's Food and Agriculture Organisation says that the situation is "alarming", with a "severe food crisis", affecting 1.8 million people, persisting throughout the country for at least the rest of the year.

Around Habiba Hassan's home no one can remember a drought this severe. Children have been dying, and the land, in her words, is "turning to desert". She has no doubt about the cause: "It's global warming." How does she know? The people of her village had learnt about it from the BBC Somali service, heard on their £2.50 radios.

Hers is just one of the African voices in a searing report on the danger that the changing climate poses to the continent, published tomorrow by 22 British environment and development charities, pressure groups and academic institutes. It shows that the world's poorest continent - the continent least able to cope with the impact of climate change - is the most vulnerable to its effects.

The report comes the day before the unveiling of a top-level Treasury review into the effects and economics of global warming, which will herald a new government initiative on the issue, headed by the Chancellor and prime minister-in-waiting, Gordon Brown, And it is published only one week before the opening in Nairobi, Kenya, of the next, crucial round of international negotiations on what is to succeed the Kyoto Protocol.

The Stern review will tomorrow spell out the enormous consequences for the world of failing to control climate change and will take issue directly with President Bush's insistence - at times apparently backed by Tony Blair - that tackling it would be economically ruinous.

It will show, on the contrary, that refusing to take action would lead to the biggest worldwide economic crisis since the Great Depression of the 1930s, with "catastrophic consequences" around the globe, whereas tackling it would be relatively inexpensive, and could, indeed, stimulate the world economy.

The 700-page review will call for immediate action, criticise the United States, take a swipe at the conventional economics that have dominated thinking for the past quarter of a century, suggest measures to cut pollution at home, and call for increased aid to help poor countries - such as those in Africa - cope with the effects of global warming.

Tomorrow's report - by the Working Group on Climate Change and Development, an alliance of 22 bodies - makes clear how urgent and necessary that will be. It is an update of a previous report by the group, "Africa - Up in Smoke?" which helped to persuade Mr Brown of the importance of the issue.

Now Habiba Hassan is urging him, and the world, to act. And so are others from Africa's grassroots, or what is left of them. Paul Mayan Mariao, a chief in the drought-stricken Turkana area of north-eastern Kenya reports in "Africa - Up in Smoke 2": "The weather is changing. We used to get heavy rains when the winds came from the west. Now the wind comes from the east, so it brings little or no rain."

And Sesophio, a Masai herdsman from Ngorongoro, Tanzania, blames "this development, like cars, that is bringing stress to the land ... We think there is a lot of connection between that and what is happening now with the droughts."

The report bears out their fears with hard facts. "Africa is steadily warming," it concludes. "It is becoming clear that in many places dangerous climate change is already taking place." The six warmest years ever recorded in Africa have all been since 1987, it says, and in many parts of the continent temperatures are expected to rise twice as fast as in the world as a whole. The result will be to drive its climate ever more towards extremes. Traditionally arid areas such as the north-east and south of the continent, and the Sahel on the fringes of the Sahara in west Africa, are becoming drier - with increased droughts - while rainy areas, such as equatorial Africa, are getting wetter, with more floods.

Even worse, perhaps, the weather is becoming increasingly unpredictable, with confusing changes in the seasons, making it harder and harder for poor farmers to know when to invest their scarce time and resources into planting, tending and harvesting their crops.

The report predicts that "climate change will reduce crop yields by 10 per cent over the whole of Africa", a catastrophic development in a hungry continent which, even now, is struggling to increase its harvests enough to feed its rapidly growing population. But even this figure, as an average, disguises much greater, more local disasters.

Tanzania, for example, expects its maize harvests to fall by a third, and its millet yield to go down by three-quarters. Meanwhile the sorghum crop, another staple, is expected to drop by as much as four-fifths in Sudan.

In all, according to other predictions, 40 per cent of Africa's countries will suffer "major losses" in cereal production. Yet four out of every five of its people depend on agriculture for their livelihoods - and the number of the desperately poor has almost doubled, to more than 500 million, in the past 25 years.

Water is becoming scarcer as drought increases - and the rain that falls comes in ever heavier storms, running straight of the land rather than filtering down to replenish supplies.

The United Nations Environment Programme's (Unep) flagship report, "The Global Environmental Outlook", says that there is only one-third as much water for each African as there was in the 1970s. Two out of three people in its rural areas, and a quarter of its urban population, do not have access to safe drinking water.

Climate change and population growth will make this far worse. The Unep report adds: "Fourteen countries in Africa are subject to water stress or water scarcity, and a further 11 will join them in the next 25 years."