Michael McCarthy: Nature can delight us - even as we destroy it

It is indeed an exhilarating feeling that the natural world still has surprises in store for us, as the discovery of Tanzania's kipunji monkey shows. For most of the 20th century we thought we had found more or less everything, certainly in terms of the Earth's large mammals. The last big beast to turn up, the okapi - a shorter-necked version of the giraffe - was discovered as long ago as 1901.

Then in the 1990s, to the great delight of anyone interested in wildlife, a whole series of animals new to science started to come to light in a region that had been closed for decades because of war - south-east Asia, and in particular, Vietnam.

In the space of a few years a dozen or so new creatures turned up in the Vietnam-ese jungles, including the saola or Vu Quang ox, deer species, monkeys and even a rhino. And as the kipunji shows, there are animals to be found in other parts of the globe. Take, for example, the area of the Democratic Republic of the Congo, south of the Congo river: there you have an area of dense rainforest the size of western Europe. What might that conceal?

Unfortunately these discoveries, these proofs of nature's richness, cannot mitigate the terrible truth about the Earth's wildlife - that a steadily increasing amount of it is on the road to extinction. Only last week the World Conservation Union published the latest version of the Red List, the official catalogue of threatened species, which shows that extinction is now considered a threat for no fewer than 16,119 types of organism, including one in eight of the world's birds, one in four mammals and one in three amphibians.

If present trends continue, the coming decades may see many iconic species disappear, at least from the wild, including tigers, polar bears and our closest relatives, the great apes.

In truth, so far as wildlife is concerned, we are at the beginning of a terrible event: the sixth great extinction. Five times in the past half-billion years, the fossil record shows, living things have been wiped out over much of the Earth, probably because of catastrophic changes in climate or the impact of an asteroid. But the sixth great extinction will be a human achievement, as we continue our destruction of forests and other natural habitats, and add to it the climatic effects of two centuries of burning coal, gas and oil on an ever-increasing scale.

All over the world, wildlife has fewer and fewer places to live, and where it lives, it is persecuted. Let's rejoice in the Earth's continuing odd surprises; but let's remember the bigger picture.