WED 2010: What is biodiversity?
Biodiversity (biological diversity) reflects the number, variety and variability of living organisms and how these change from one location to another and over time. Biodiversity includes diversity within species (genetic diversity), between species (species diversity), and between ecosystems (ecosystem diversity).
The species diversity in the planet is presumed to be between 5 and 50 million, although only around two million of these are actually known today. The most diverse group of organisms is insects, followed by plants. In addition, 90% of the species in the world may be found in tropical forests, which extend over only about 7% of the planet's surface.
Biodiversity is very important for humans and our survival. We depend upon biodiversity to satisfy basic needs like clean water, food and medicine, as well as to enrich our lives culturally or spiritually. Biodiversity is also responsible for environmental services (services provided by nature) such as the regulation of the gases in our atmosphere, protection of our coasts, maintenance of the water cycle, regulation of the climate, conservation of fertile soils for agriculture, recycling human waste and absorbing pollution, and many others.
Read key findings of the Millenium Ecosystem Assessment
Unfortunately, biodiversity is in decline worldwide, affecting the goods and services that depend on vital ecosystems and in turn affecting human well-being. The most important direct drivers of biodiversity loss are:
- habitat loss
- climate change
- invasive exotic species
- overexploitation
- pollution
Deforestation, for the purpose of clearing land for agriculture and cattle ranching, is a major contributor to habitat loss. Since 2000, the loss of forests has been estimated at 6 million hectares annually. Moreover, the global area of forests has been reduced by one half over the past three centuries and forests have effectively disappeared in 25 countries while another 29 coutries have lost more than 90% of their forest cover.
The extinction of species is one of the most important consequences of biodiversity loss. Although species' extinction is a natural process, human activity has managed to intensify it. Today, approximately 24% of the world's mammals and 12% of bird species are threatened with extinction. The rapid destruction of many of the richest ecosystems in the world has lead experts to conclude that one fourth of the total biological diversity in the planet could be under serious threat of extinction during the next 20 to 30 years.
Many of the planet's species have already been lost or condemned to extinction because we took so long to act. It is too late to preserve all the biodiversity our planet once had. But in order to achieve greater progress toward biodiversity conservation it is necessary to design and strengthen the conservation and sustainable use of the natural world.