Nobody knows how many species are being lost each year, nor the total number of species that exist.
What we have...
Biologists estimate there are between 5 and 15 million species of plants, animals, and micro-organisms existing on Earth today, of which only about 1.5 million have been described and named. The estimated total includes around 300,000 plant species, between 4 and 8 million insects, and about 50,000 vertebrate species (of which about 10,000 are birds and 4,000 are mammals).
...and what is being lost
Today, about 23% (1,130 species) of mammals and 12% (1,194 species) of birds are considered as threatened by IUCN.
Why are species disappearing?
Global biodiversity is being lost much faster than natural extinction due to changes in land use, unsustainable use of natural resources, invasive alien species, climate change and pollution among others.
Land conversion by humans, resulting in natural habitat loss, is most evident in tropical forests and is less intensive in temperate, boreal and arctic regions. Pollution from atmospheric nitrogen deposition is most severe in northern temperate areas close to urban centres; and the introduction of damaging alien species is usually brought about through patterns of human activity.
Species loss is also compounded by:
- the ongoing growth of human populations and unsustainable consumer lifestyles
- increasing production of waste and pollutants
- urban development
- international conflict.