Biodiversity

The Convention on Biological Diversity defines biological diversity broadly as variability among living organisms from land, marine and other aquatic environments, including diversity within species, between species and among ecosystems. These are often described as genetic, species and ecosystem diversity. They are connected: genetic variation exists within populations, species interact in communities, and those communities form part of ecosystems that include non-living conditions such as soil, water and climate. Biodiversity is therefore more than a tally of named species; its description depends on the scale and kinds of variation being considered.

Living things affect one another through feeding, competition, pollination, decomposition and many other relationships. These interactions help sustain ecological functions, while nature contributes food, fresh water, materials, medicines, pollination and climate regulation. The importance of particular species or habitats varies by place and context, and the benefits people receive depend on how ecosystems are managed. Changes in one level of biodiversity can also influence others, so a single measure—such as the number of species—cannot describe every dimension of ecological change.

Biodiversity is not fixed: populations change, species evolve and extinctions occur over geological time. The 2019 global assessment by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), however, found that human-driven losses were widespread and accelerating. It identified changes in land and sea use, direct exploitation of organisms, climate change, pollution and invasive alien species as the five direct drivers with the largest global impacts in its assessment. The report estimated that around one million animal and plant species were threatened with extinction; this is a finding from that 2019 assessment, not a current census of all species.

Conservation aims to maintain the variety of life and the ecological relationships that support it. Approaches include protecting and restoring habitats, managing fisheries, forests and farms sustainably, controlling pollution and invasive species, and conserving genetic resources both in natural settings and in collections. Decisions can involve trade-offs among food, livelihoods, infrastructure and habitat protection. The IPBES assessment emphasizes that responses need to address the pressures together and account for local conditions and knowledge; safeguarding biodiversity is not only a matter of setting aside protected areas.