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What is the scale of biodiversity loss?

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. A recent report indicated that one million species could be threatened with extinction. Since 1500, 1.6% of birds, 1.9% of mammals and 2.2% of amphibians have been recorded as extinct. Between 1990 and 2020, around 420 million hectares of forest (mainly tropical forest) has been lost and a further 10 million hectares, an area the size of Scotland and Wales combined, is being lost each year.

Extinctions have always occurred but the rate at which they are happening now far exceeds the rates at which species have naturally gone extinct over the course of the fossil record. The historical spread of humanity over the planet has been associated with waves of extinctions in other species. Key threats to date have been over-hunting and harvesting of species by people, habitat conversion and degradation, and the introduction of invasive species caused by human migration, settlement, trade, agriculture and resource extraction. These threats have been accelerating since 1500 alongside rapid growth in human populations and increasing growth in per capita consumption of resources. In addition, in the past few decades, climate change has become an increasingly important threat. Estimates suggest that extinction rates in the recent past have been running tens to hundreds of times faster than in pre-human times and that the pace is accelerating.

In those groups of plants and animals that have been systematically assessed under International Union for Conservation of Nature Red List criteria, about 25% are classified as threatened with extinction (that is, Critically Endangered, Endangered, or Vulnerable). Five groups (mammals, birds, amphibians, corals, and cycads) have been comprehensively assessed two or more times since 1980. In all cases the reassessments show an increasing trend in the proportion of species that are threatened.

Comparing the results of surveys of insects from the 1970s and 1980s to what we have now is helping to create a picture of changes in biodiversity. However, there is a lot more work required to understand these changes and their consequences. 

For more on this topic visit Past and future decline and extinction of species | Royal Society and Consumption patterns and biodiversity

Find answers to 16 key questions about biodiversity

  • Introduction

    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.

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  • What is biodiversity?

    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.

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  • Why is biodiversity important?

    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.

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  • How do we measure biodiversity?

    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.

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  • What is the scale of biodiversity loss?

    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.

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  • We regularly hear of new species being discovered - does that not offset the loss of existing species?

    Every year thousands of previously unknown species are discovered, described and named.

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  • Where is most biodiversity loss happening and why?

    Biodiversity loss has been most pronounced on islands and in specific locations around the tropics.

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  • Is the rate of biodiversity loss increasing or decreasing?

    Compared to the 1.6 million species known about on Earth, the number of recorded extinctions can seem very low.

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  • What is the state of biodiversity in the UK?

    The UK boasts more than 70,000 known species of animals, plants, fungi and microorganisms.

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  • How do humans affect biodiversity?

    Humanity impacts the planet's biodiversity in multiple ways, both deliberate and accidental.

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  • How does the growing global population and increasing consumption affect biodiversity?

    Since the middle of the 20th century, the human population has grown dramatically.

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  • How does climate change affect biodiversity?

    The environmental changes being driven by climate change are disturbing natural habitats and species in ways that are still only becoming clear.

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  • How does deforestation affect biodiversity?

    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.

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  • What can we do to protect biodiversity?

    Loss of natural habitats has been taking place over thousands of years, but scientists are confident that we have ways to help biodiversity recover.

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  • What can I do as an individual to protect biodiversity?

    While large scale changes in behaviour, policies and measures will be essential, individuals have a vital part to play.

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  • Can we allow nature to regenerate without intervention?

    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.

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  • How do we decide what is worth saving or putting our efforts into protecting?

    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.

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