Biodiversity loss has been most pronounced on islands and in specific locations around the tropics, where distinctive species often evolve in isolation from the rest of the world. The introduction of alien species along with hunting and the clearing of vegetation by humans on small, isolated islands account for around 80% of known extinctions. Wider problems such as climate change, pollution, over-exploitation, and land use change - often to make way for agriculture - are causing biodiversity to decline in other areas such as in the oceans and rainforests.
While much species loss has taken place in specific locations, it is often driven by global systems, with choices and actions taken in one place having effects far away.
One recent analysis found that approximately 60% of total global biodiversity loss for bird and mammal species has occurred in just seven countries between 1996 and 2008 – Indonesia, Malaysia, Papua New Guinea, China, India, Australia and the USA, where the majority has occurred on the islands of Hawaii.
Due to their relative isolation, islands tend to be home to wide varieties of unique species and habitats, often making them biodiversity hotspots. The limited habitats that species have on islands, however, makes them exceptionally vulnerable. Foreign species introduced to an island either accidentally or deliberately by humans can quickly out compete or directly destroy native populations. In Hawaii and most other tropical islands, for example, foreign species such as rats, feral cats, pigs, goats and non-native plants have decimated the local flora and fauna, which have not evolved to cope with the pressure from these introduced species.
Biodiversity loss also affects larger islands. On Madagascar, for example, deforestation, mining and climate change are causing significant habitat loss and threatening native species. Similarly, Australia lost 5-10% of its biodiversity between 1996 and 2008 while high levels of deforestation to make way for agricultural plantations have particularly affected the species rich rainforests of Indonesia.
In the past 20 years extinctions have also become common on continents. Most threatened species can be found in areas where large human populations are concentrated, such as southeast China and the Western Ghats of India. According to the World Wildlife Fund's Living Planet Report 2020, Latin America and the Caribbean have suffered notably high losses of amphibians, reptiles and fish due to a combination of threats including disease, habitat loss and over-exploitation.
Biodiversity loss, however, is not just confined to the land. Life in the oceans is being threatened by overfishing, habitat degradation, pollution, and acidification due to rising carbon dioxide levels in the sea water. Corals, for example, have undergone dramatic declines since the mid-1990s.
For more on this topic Past and future decline and extinction of species | Royal Society
At its simplest, biodiversity describes life on Earth – the different genes, species and ecosystems that comprise the biosphere and the varying habitats, landscapes and regions in which they exist. We've answered some of your most popular questions about biodiversity.introduction
Biodiversity is all the living things on our planet – from the smallest bacteria to the largest plants and animals. So far, we have identified around 1.6 million species but that is probably only a small fraction of the forms of life on Earth.Read the full answer
Biodiversity is essential for the processes that support all life on Earth, including humans. Without a wide range of animals, plants and microorganisms, we cannot have healthy ecosystems.Read the full answer
There is still much we do not know about the complexity of biodiversity on Earth. There are a number of ways that we measure it, with counting species the most common approach.Read the full answer
The list of known recent extinctions is still a small fraction of all species on the planet but it is far above prehuman levels and the evidence suggests it is rising fast.Read the full answer
Every year thousands of previously unknown species are discovered, described and named.Read the full answer
Biodiversity loss has been most pronounced on islands and in specific locations around the tropics.Read the full answer
Compared to the 1.6 million species known about on Earth, the number of recorded extinctions can seem very low.Read the full answer
The UK boasts more than 70,000 known species of animals, plants, fungi and microorganisms.Read the full answer
Humanity impacts the planet's biodiversity in multiple ways, both deliberate and accidental.Read the full answer
Since the middle of the 20th century, the human population has grown dramatically.Read the full answer
The environmental changes being driven by climate change are disturbing natural habitats and species in ways that are still only becoming clear.Read the full answer
Forests contain some of the richest concentrations of biodiversity on the planet. But between 1990 and 2020, around 420 million hectares of mainly tropical forest has been lost.Read the full answer
Loss of natural habitats has been taking place over thousands of years, but scientists are confident that we have ways to help biodiversity recover.Read the full answer
While large scale changes in behaviour, policies and measures will be essential, individuals have a vital part to play.Read the full answer
Biodiversity loss is a complex issue involving many overlapping processes. While nature can recover when left to do so, it requires dramatic changes in our behaviour for this to happen.Read the full answer
The value of the natural world can be interpreted in many ways, from their raw economic value to the inherent social, cultural and emotional benefits they provide.Read the full answer
Find the main authors and reviewers of the questions and answers on biodiversity.See more