The diversity of life forms, which is constantly re-evaluated, includes 1.75 million species identified and between 3.6 and 15 million species yet to be discovered. 12% of the 10,000 species of birds are threatened or in danger of immediate extinction, as are 23% of the 4,776 species of mammals, 46% of fish, a third of amphibians and 70% of plants. Among the mammals, the 240 primates other than the human species are in danger and almost half on the path to extinction.
In the last 40 years, half of wild animals have disappeared. This massive extinction of species is not a new phenomenon. The history of the Earth is littered with major extinctions. What is different is the speed of current developments.
The richness of biodiversity increases the chances of life on Earth to adapt to changes. Studying it raises numerous questions that as yet remain unanswered: what are the loss thresholds above which the balance of the ecosystems is under threat? What is the resistance of the ecosystems to human interference? How will biodiversity react to climate change?
The Convention on Biological Diversity (Rio de Janeiro 1992) defines biodiversity as “the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems”.
In every ecosystem, living creatures including humans interact with one another as well as with the air, water and land. Due to global warming – which leads to the displacement of species in both space and time (annual blooming seasons, for example) – and the disappearance of certain species, 60% of inter-species interaction has been eliminated (IUCN estimates 2006). The more species a functional group contains, the less vulnerable it is. A change in one of its components can affect the entire system. Conversely, saving one particular species can only succeed if the function of the entire ecosystem in which it lives is guaranteed.
Factors such as habitat fragmentation (by roads for example), heavy extraction in the environment, pollution and climate warming jointly contribute to today’s high rate of extinction, estimated to be between 1000 and 10,000 times higher than it has been over the last 60 million years. Humankind leaves its footprint on 83% of the Earth’s surface, a pressure that animals, plant species and microorganisms are less and less able to withstand.
A vast natural capital
From a utilitarian viewpoint, ecosystems provide humankind with numerous goods and services – for what we eat (farming and fishing require a rich ecosystem), what we make (wood, rubber, wool, wicker fibre, combustibles etc.) and for our health: over half of all pharmaceutical substances are plant-based (only 5,000 of the world’s 250,000 flowering plants have been studied for potential therapeutic properties), or mushroom-based (penicillin and other antibiotics for example). Pollination, the spreading of seeds, insect population control and nutrient recycling all occur as a result of interactions between living organisms. When species disappear and biodiversity is reduced, nature cannot provide these services. When humans burn down the Amazon jungle, they are burning one of the biggest reserves on Earth of genetic information that could be used for multiple purposes, nutritional and medical in particular.
The intrinsic value of many species – known and unknown – make the creation of a large-scale strategy to prevent their extinction essential. The annual contributions of biological diversity to humankind are estimated to be between $29 trillion and $380 trillion. In the world’s poorest countries, natural capital is said to represent on average 25% of an individual’s wealth. This figure falls to 1% in rich, urbanized countries.
Of 9,775 known bird species, 70% are endangered, including 1,212 facing immediate extinction. Habitat destruction is a frequent cause, as is the case in Singapore where 61 species became extinct with the destruction of the country’s tropical forests. In England over the last thirty years, between 50 and 80% of all willow warblers, song thrushes and spotted flycatchers have disappeared, likely due to the destruction of hedges and thickets and the use of pesticides. In India and Southern Asia, three types of vultures – the long-billed, slender-billed and oriental white-backed varieties – were placed on the IUCN’s red list of threatened species in 2004; since the 1990s, populations have dropped by 97% due to an anti-inflammatory drug given to cows that the birds eat.
The surface over which 173 emblematic mammal species have traditionally been distributed has been reduced by 50% over six continents. This stems from cutting down one third of the Earth’s forests since the first agrarian societies appeared. All primate species are endangered and half of them face extinction due to habitat destruction and poaching. Bonobo populations have fallen 97%, from around 100,000 animals in the 1980s to 3,000 today.
Fish and Coral
37% of freshwater fish in North America’s lakes and rivers are either extinct or face extinction; since 1995, 10 species have disappeared. In Europe, nearly 80% of the region’s 193 known freshwater fish species are endangered. Climate warming could lead to the disappearance by 2100 of all the world’s coral and the ecosystem it supports. Indeed, coral ecosystems are under serious threat from pollution, hurricanes and the overexploitation of fish stocks in addition to the adverse effects of global warming. Coral bleaching is the most obvious indicator of this deterioration.
34 Biodiversity Hotspots
Scientists have drawn up a list of 34 biodiversity hotspots. This concept of hotspots was developed by the NG) Conservation international (CI). These are regions that are particularly rich in biological terms, and which contain over 1,500 endemic varieties of vascular plants and have lost at least 70% of their original habitat. While they only cover 2.3% of the Earth’s surface, these areas are home to 50% of all vascular plant varieties and 42% of land invertebrates. Nearly 38% of hotspots are located in protected areas such as parks and reserves, while 68% are in non-protected areas. Notable hotspots include the Mediterranean basin, the Cerrado in South America (which holds at least 10,000 plant varieties, 4,000 of which are endemic), Madagascar, South-East Asia, the mountains of Central Asia, New Zealand and the islands of the Indian Ocean.
According to Lester R. Brown (2007), “we are witnessing the preliminary stages of a sixth wave of extinctions. Unlike the other five, which were caused by natural phenomena, this one is attributable to humans. For the first time in history, […] a species has evolved to a point where it is capable of eradicating other forms of life. […] The number of species with which we share the planet decreases as the human population increases”.