BIODIVERSITY IN CRISIS The most obvious manifestation of biodiversity loss is the extinction of species.

This is a natural phenomenon: species have been going extinct since life began. Indeed, it is estimated that many more species have gone extinct than exist at present. What's worrying is the rate at which species are currently dying out: not since the demise of the dinosaurs (some ! million years ago" has earth witnessed an 'extinction event' of such catastrophic scale. #ince the total number of species on earth can only be estimated, the exact rate of current species loss is difficult to gauge. The figure probably stands at between !$ and %!$ extinctions per day. Wor&ing from the conservative estimate that earth is home to %$ million species in all, this means that between $.' and $. percent of species are being lost every year. This rate is at least %$,$$$ times greater than the (bac&ground) or natural rate of species extinction, as estimated using the fossil record. The World *onservation +nion (I+*," has estimated that over !,!$$ species of animals including birds, mammals, reptiles, amphibians, fishes and invertebrates - are currently threatened with extinction, together with ,.$$ species of higher plants. Those considered vulnerable, threatened, or critically endangered include: *lose to %,%$$ species of mammals (about '/ per cent of the total number". 0ver %,%$$ birds (around %' per cent of &nown species". 0ver .!$ species of fish (/12 per cent of total surveyed". 3round '1$ species of reptiles ( ' per cent of total number surveyed". 3n estimated %!. species of amphibians (41 per cent of the total number surveyed". Over 5,500 species of animals are threatened with extinction The annual extinction rate is set to rise still further. 5minent biologist 5dward 0. Wilson has estimated that if current trends continue, a fifth of all species will go extinct within the next 4$ years. The picture is no more encouraging from an ecosystem perspective: 6ore than !$ per cent of the world)s wetlands have been drained. #ince %1!$, some 4 billion hectares of forest cover - nearly half - has been lost. 5ach year, a further % million hectares of forest are destroyed. 7etween !$ and 8$ per cent of mangrove ecosystems have been destroyed. 9oughly one:third of the world)s coral reef systems have been destroyed or highly degraded.

0ne fourth of the planet)s topsoil has been lost. 1 per cent of the world)s ma;or fish stoc&s are either fully exploited, over:fished, depleted, or slowly recovering, and productivity has fallen in all but four of the %! most important fishing regions. ,early ' billion hectares of crop and gra<ing land are suffering from moderate to severe soil degradation.p

=enetic diversity within species is also being eroded. This trend is especially alarming from an agricultural perspective. #ince %1$$, some three:>uarters of the genetic diversity of cultivated crops has disappeared, together with nearly half of the gene pool of the wild relatives of domestic animals. The loss of genetic diversity matters because a large proportion of the world)s agricultural systems depend on the regular assimilation of wild genes to stay one step ahead of the threat posed by pests and diseases. The main causes of biodiversity loss are considered under the follo in! headin!s" #abitat destruction 5cologists estimate that an area of ten s>uare miles contains twice as many species, on average, as an area of one s>uare mile, suggesting that to reduce an area of ecosystem to a tenth of its original si<e will cause half its species to become extinct. 3nimals at the top of the food chain (lions, bears, etc." re>uire especially large habitats in order to maintain viable wild populations. Invasive s$ecies 5cosystems are fragile balancing acts, evolved over millions of years as an integrated whole. The sudden introduction to a given ecosystem of an alien species can severely disrupt its normal functioning - with disastrous conse>uences for native species. #uch introductions are usually the result of human activities. The accidental introduction to the 7lac& #ea of an 3tlantic comb ;ellyfish species is a well:&nown example. These invaders have out:competed native fauna, and now comprise some 1! per cent of the 7lac& #ea)s total biomass (a disaster for the local economy". In the +#, meanwhile, the introduction of exotic species has been implicated in close to .$ per cent of the past century)s freshwater fish extinctions. %ollution The chemical contamination of fresh water, seawater and soils can lead to the disappearance of populations and species. 3gricultural runoff, containing fertili<ers and pesticides, can seep into a>uifers and rivers eventually reaching the ocean. 0nce present in the food chain, contamination can have far reaching conse>uences such as in the case of the decreased barn owl population in the +nited ?ingdom that resulted from the introduction of new rodenticides. 3dditionally, atmospheric pollution has contributed to accelerated climatic change with expected conse>uences including the disruption of species distribution and even extinction. Over&harvestin! 6any species have been harvested or hunted to rarity and beyond. 5xamples of such directly wrought extinctions include those of the passenger pigeon and the *arolina para&eet in the early

part of the twentieth century. 6ore recently, the *entral 3frican (bushmeat) trade has placed mountain gorillas and chimpan<ees under direct threat. Climate chan!e 0ver the past century or so, global temperatures have risen by between $.4 and $. @* (the largest increase in at least %,$$$ years", due in large part to the increased presence in the atmosphere of 'greenhouse gases' from industrial processes. The effects of climate change have so far included a rise in sea levels of some %$:'! cm worldwide, a loss of glacier ice, changes in precipitation patterns, and an increased occurrence of extreme weather events. These fluctuations have disturbed seasonal cycles throughout the globe. It is feared that these changes are happening at too fast a rate for many species to adapt. Aespite that the growth of human societies is the prime mover behind every one of these five more immediate factors, biodiversity loss is not the inevitable result of social and economic growth and development. 5nvironmental sustainability is possible. 7ut there are a number of specific factors standing in the way of its widespread achievement. These factors originate in some of the most basic social, economic, political, cultural and historical features of society. They include: 'ar(et and economic $olicy failures such as inappropriate regulatory mechanisms, harmful subsidies and incentives, inade>uate economic valuation of biodiversity, the absence of local and global mar&ets for biodiversity goods and services and the lac& of clear environmental and development policies. Social) $olitical and institutional ea(nesses such as unsustainable production and consumption patterns, poverty, lac& of clear land use rights, uneven distribution of land ownership, poor governance, fragmented decision ma&ing, lac& of political will, political unrest and wars. *ac( of (no led!e of biodiversity+s im$ortance, particularly among hose directly involved in the management of biodiversity and among economic and developmental decision:ma&ers. With these factors in mind, it is clear that ;ust as humanity depends on biodiversity for its survival and development, the long:term survival of earth)s biodiversity will necessitate the achievement of sustainable human development.