Your Planet: The state we're in

All over the planet, environmental alarm bells are ringing. Michael McCarthy faces up to some disturbing facts

The big heat

Portuguese firefighters struggle to contain yet another conflagration this summer, as flames sweep across the nation during its worst ever drought. 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 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. 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and other countries are struggling to meet their initial commitments to do so under the Kyoto protocol, and the US has withdrawn from the treaty. Fires such as these, which burned across Portugal like an angry rash, may be a frightening vision of Europe's future

Meltdown

Today'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. All over the planet, these great fields of ice are melting, in some cases more rapidly than they have ever done in recorded history. 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. Antarctic ice shelves (over the sea) and ice sheets (on land) are also melting and in some cases breaking up, while most of the world's glaciers are shrinking. One of the most famous, which forms the instantly recognisable snowy peak of Kilimanjaro, the 'shining mountain', has nearly gone and will vanish in the next 15 years

The high tide

It will not be sudden, like the Boxing Day tsunami; it will be slow and stealthy. But its effects will be even greater, wider and longer-lasting. Sea-levels are rising all around the world: not because of melting ice, but because, as water warms, it expands in volume. This 'thermal expansion' of the oceans is causing sea levels to move upwards at between 1mm and 2mm per year. But this rate is likely to increase sharply, and during the coming century global sea levels are expected to rise by anything up to 80cm, or 3ft. For countries with large areas of low lying land, such as Bangladesh, that may well be catastrophic. Closer to home, East Anglia and the Thames Estuary will be threatened. Later, as climate change progresses further, the melting of giant land-based ice sheets such as the one covering West Antarctica may come into play; that alone would raise sea levels by 16ft, and London would be under water

Acid oceans

Scientists have just begun to realise that the main greenhouse gas causing global warming, carbon dioxide, is also a potential menace to marine life on a huge scale, as it is starting to produce carbonic acid as it is dissolved in sea water. This process is altering the chemical composition of the sea from slightly alkaline, which it has been for millions of years, to acidic, and is producing an environment in which many vital organisms may not survive. Ocean acidification may wipe out much of the microscopic plankton at the base of the marine food web, and have a knock-on fatal effect up through shellfish, to major human food species such as cod. It is already having a serious impact on organisms such as coral, and putting a question mark against the future of coral reefs. Expect to hear much more about this potentially devastating problem

Lost forests

Stark as a shaven head, this recent picture from the state of Mato Grosso in Brazil makes plain the current reality of deforestation in the Amazon. Despite decades of protests, the obliteration of the world's largest rainforest - aeons old and fantastically species-rich - continues at a headlong rate . The survival of the Amazon forest, which sprawls over 4.1 million sq km (1.6 million sq miles) may be one of the keys to the survival of the planet. It is sometimes called the world's "lung" because its trees produce much of the world's oxygen; but nearly 20 per cent of it has already been destroyed by legal and illegal logging and clearance for cattle ranching. The rate of destruction in 2004 was the second-highest on record, with an area nearly the size of Belgium cut down. It is now being driven by the soy boom, the replacement of the forest with soya beans plantations to make cattle feed

Dying species

The fossil record shows us that there have been five great extinctions of living species in the history of the earth, when most life died out; the last was 65 million years ago. Now, many scientists believe, we are in the middle of a sixth great extinction - caused this time by human activities such as habitat destruction, overexploitation and pollution. About 11 per cent of all bird species are regarded as endangered, as are about 20 per cent of reptiles, 25 per cent of both amphibians and mammals, 33 per cent of all fish species - and perhaps 40 per cent of all plant species. The next two decades may see the disappearance of many species in the wild, including the tiger and the great apes. It is thought that only about 15,000 of our closest relatives of all, bonobos or pygmy chimpanzees (pictured), now survive in Africa's Congo basin

Empty seas

The UN's Food and Agriculture Organisation said this year that 52 per cent of the world's fish stocks are already fully exploited, and another quarter are on the way to be being destroyed. A recent review of marine fisheries concluded that 90 per cent of the world's large predatory fish, including tuna, swordfish, cod, halibut and flounder, have disappeared in the past 50 years. Marine life is being hammered by brutal technology: enormous trawlers which draw enormous nets that kill everything they touch, from unwanted fish species to dolphins and turtles; which pull lines of hooks miles long that threaten nearly all the world's albatrosses with extinction; and which destroy marine habitats by dragging massive trawls across the sea bed. The Royal Commission on Environmental Pollution has called the wrecking of the seas the world's gravest environmental problem after climate change

Super-storms

Mathematical models of the world's climate system agree that global warming will lead to an increase in 'extreme events' in the weather. Rainfall will be more torrential; violent storms more violent still. Such events will present dire threats to human settlements, as we have seen from such examples as Gautemala City, wrecked by the unusual force of Hurricane Mitch in October 1998; London, where storm drains could not cope with an unusually strong downpour in August 2004, causing huge volumes of raw sewage to be released into to the Thames; and, now, the wreck of New Orleans. Did climate change contribute to Hurricane Katrina's violence? No one can say for certain, but it is certainly consistent with predictions. In August, a leading US meteorological scientist, Kerry Emanuel, explicitly linked global warming to a significant increase in the power of hurricanes since the mid-1970s

Toxic toll

In developed countries, some of the worst of polluting heavy industry has been cleaned up; the industrialisation of farming remains problematic: it is estimated that more than 2.8 million tonnes of artificial chemical pesticides are sprayed worldwide each 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. 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. Meanwhile, countries such as China, dashing for growth and Western living standards, are having terrible industrial pollution problems

Water of life

Already, the issue of water is critical for much of the world. 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. Britain's Met Office has estimated that by the end of this century the kind of terrible drought experienced this summer in Portugal - which would have been a once-in-400-years event, before we started piling up CO ₂ in the atmosphere - would be 10 times more frequent. It would be rash to assume that such events will be confined to Portugal