The term was coined in 1985 – a contraction of “biological diversity” – but the huge global biodiversity losses now becoming apparent represent a crisis equalling – or quite possibly surpassing – climate change.
More formally, biodiversity is comprised of several levels, starting with genes, then individual species, then communities of creatures and finally entire ecosystems, such as forests or coral reefs, where life interplays with the physical environment. These myriad interactions have made Earth habitable for billions of years.
A more philosophical way of viewing biodiversity is this: it represents the knowledge learned by evolving species over millions of years about how to survive through the vastly varying environmental conditions Earth has experienced. Seen like that, experts warn, humanity is currently “burning the library of life”.
Mind-bogglingly diverse. The simplest aspect to consider is species. About 1.7 million species of animals, plants and fungi have been recorded, but there are likely to be 8-9 million and possibly up to 100 million. The heartland of biodiversity is the tropics, which teems with species. In 15 hectares (37 acres) of Borneo forest, for example, there are 700 species of tree – the same number as the whole of North America.
Recent work considering diversity at a genetic level has suggested that creatures thought to be a single species could in some cases actually be dozens. Then add in bacteria and viruses, and the number of distinct organisms may well be in the billions. A single spoonful of soil – which ultimately provides 90% of all food – contains 10,000 to 50,000 different types of bacteria.
Biodiversity is crucial for South Africa’s food security
The concern is that many species are being lost before we are even aware of them, or the role they play in the circle of life.
How bad is it?
Very. The best studied creatures are the ones like us – large mammals. Tiger numbers, for example, have plunged by 97% in the last century. In many places, bigger animals have already been wiped out by humans – think dodos or woolly mammoths.
The extinction rate of species is now thought to be about 1,000 times higher than before humans dominated the planet, which may be even faster than the losses after a giant meteorite wiped out the dinosaurs 65m years ago. The sixth mass extinction in geological history has already begun, according to some scientists.
Lack of data means the “red list”, produced by the International Union for Conservation of Nature, has only assessed 5% of known species. But for the best known groups it finds many are threatened: 25% of mammals, 41% of amphibians and 13% of birds.
Species extinction provides a clear but narrow window on the destruction of biodiversity – it is the disappearance of the last member of a group that is by definition rare. But new studies are examining the drop in the total number of animals, capturing the plight of the world’s most common creatures.
A global treaty, the Convention on Biological Diversity (CBD), has set many targets. Some are likely to be reached, for example protecting 17% of all land and 10% of the oceans by 2020. Others, such as making all fishing sustainable by the same date are not. The 196 nations that are members of the CBD next meet in Egypt in November.
In his 1985 text, Prof E O Wilson, concluded: “This being the only living world we are ever likely to know, let us join to make the most of it.” That call is more urgent than ever.
