Between 2 and 3 bn people – more than a third of the global population – have no access to clean water on a daily basis. Now global warming is set to worsen the problem: a recent report by British aid groups on the effects of climate change on Africa said that the 14 African countries already subject to water stress or water scarcity will be joined by a further 11 nations in the next 25 years, as rainfall declines with climate change Nor will Europe be exempt. In developing countries, poverty and the climb out of poverty bring pollution. Poor people tend to rely on open fires in enclosed spaces for cooking and heating; the consequent indoor air pollution may contribute to about two million deaths a year. According to the World Health Organisation, more than 3m people are poisoned by such pesticides every year, and more than 220,000 are killed; meanwhile, Britain’s farmland bird population has dropped by 40 per cent in 30 years. Last year a major study reported that Arctic sea ice has thinned by nearly half in 30 years, and is now melting so extensively that by the end of the century it may have vanished completely. All over the planet, these great fields of ice are melting, in some cases more rapidly than they have ever done in recorded history.

Fires such as these, which burned across Portugal like an angry rash, may be a frightening vision of Europe’s future

MeltdownToday’s most alarming signs of global warming are paradoxically to be found in the world’s coldest places: in the polar ice sheets, in the glaciers of the great mountain chains, even in the snow-capped summit of Africa’s highest peak, Kilimanjaro in Tanzania. Only a massive effort by all countries to cut back emissions of greenhouse gases could offer any hope of avoiding this fate; yet Britain and other countries are struggling to meet their initial commitments to do so under the Kyoto protocol, and the US has withdrawn from the treaty. The steady accumulation in the atmosphere of carbon dioxide and other waste gases from industry and transport is retaining more and more of the sun’s heat, and global average temperatures are projected to rise by anything up to 6 deg C by 2100. Similar scenes are likely to be much more frequent over southern Europe in coming decades with summer droughts predicted to be fiercer and longer.

The big heat

Portuguese firefighters struggle to contain yet another conflagration this summer, as flames sweep across the nation during its worst ever drought. That’s why – contrary to the beliefs of some weirdly reactionary versions of environmentalism – people did not burn up the earth’s store of fossil fuels because they were “greedy” or “selfish”. They did it because they were hungry and cold and desperate to live a decent life. It’s easy to understand why they acted like this.But there were two problems that lay dormant within this planetary experiment with fossil fuels, and their shape has finally become clear in the past 20 years. Oil is simply solar energy trapped by plant life millions of years ago, stored and repackaged by nature underneath the earth’s surface.

By releasing all that solar energy in a sudden burst over the space of just two centuries, humans unwittingly changed the physics and chemistry of the planet we live on. Levels of greenhouse gases – which trap heat in the atmosphere – nearly doubled, causing rising temperatures; a planetary fever The results are now visible all over the world. All the hottest years on record have occurred in the past 15 years. The seasons are changing, with deadly results across the developing world. The peaks of Mount Kilimanajaro are now naked of snow for the first time in our own 10,000-year geological period.Oil, it turned out, was an unintentional weapon of mass destruction. Many climatologists now warn that it has triggered a global warming “positive feedback loop”. This is when a system begins to move in a certain direction, and then responds to this change in a way that makes the process faster and faster, like tossing more fuel into the engine of a runaway train It sounds complicated, but in fact it is startlingly simple Look at the world’s ice cover.