The Club of Earth warned in 1986 that the destruction of biodiversity was a threat to civilization - second only to thermonuclear war - in its severity.

But what exactly is biodiversity?
Biological diversity is the variety and relationships between all living things in the world: from microbes to insects to plants to animals and people. It refers to the range of genetic, species and ecosystem diversity of the Earth's biosphere, which includes its atmosphere, water systems and crust.

Most scientists agree that there are about 13 million species in the world, but some guesstimate that there could be as many as 100 million. However, researchers have identified only about 1.75 million species so far. Only a fraction of 1 per cent of the world's species has been properly studied for its potential value to humanity - and that doesn't include its value to the world's ecosystem.

But the diversity of life is being lost at an unprecedented speed. Species are now becoming extinct at 1,000 times the natural rate - or much faster, according to some. And the pace is likely to quicken if we don't take measures to reverse the trend. Some scientists think that by 2050, half of all the species alive in 1992 could be lost forever.

We humans are the greatest threat to this diversity. We are destroying natural habitats so rapidly that we cannot even assess the extent of the damage. For example, foresters in the temperate rainforest in the northwestern United States had been burning a tree that they considered a weed. After years of clinical trials, it was determined in 1991 that the Pacific yew contained the most important anti-cancer drug in 15 years. But the harm to its habitat nearly destroyed all hope of using it to treat patients. This is only one example of the value nature possesses. Because we're degrading so many ecosystems so rapidly, we may never know what could have been.

Some of the most biologically diverse areas in the world are also the most threatened. Recent analyses identify 34 regions worldwide where 75 per cent of the most threatened mammals, birds and amphibians live. These 'hot spots', which also have numerous plant and insect species, cover only 2.3 per cent of the planet's surface. Therefore, many governments, groups and individuals have been focusing their energy on assuring these areas are protected from damage.

Does this mean we should focus our energy on just these areas? Many biologists say that this is the wrong approach. The bottom line is that we simply don't know how much the world holds, so converting or destroying lands haphazardly might have repercussions beyond our comprehension.

Fishing to the limit
Fish provide 16 per cent of all the protein we eat. The world's wild fish catch has increased from less than 20 million tonnes in 1950 to more than 93 million tonnes in 2002. We may have reached the limit: 75 per cent of the Earth's marine fish stocks are now fully exploited or overexploited. And to meet increasing demand, we are fishing further and further down the food chain, making it more difficult for individual species to recover.

State of marine fish stocks:

Source: FAO/UNEP/MEA