A few facts
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Conditions on planet Earth change naturally over time. Life can adapt to new circumstances over many generations through a process called evolution. But species that can't adapt fast enough go extinct. If conditions change rapidly, life has no time to adapt, for example when a large meteorite strikes Earth, a large volcanic eruption occurs, or the climate changes suddenly.
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Fossil records tell us there is a natural background extinction rate of about one or two species per year. Scientists estimate extinction rates are now 1,000 times the background rate.
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Abundant, widespread species tend to survive between one and ten million years, according to fossil records.
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We know there have been five mass extinctions in the past. The last, 65 million years ago, wiped out the dinosaurs.
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Mass extinctions are dramatic, but they only account for about 4% of all species extinctions in the Earth's history.
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There is a big difference between the current loss of biodiversity and previous extinctions. Physical events caused mass extinctions in the past. One life-form is overwhelmingly responsible for present-day extinctions - humans - you and me.
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Biodiversity is not evenly spread across the planet. Some habitats, such as coral reefs, are astonishingly rich in the number and type of species they support, whereas others are relatively species-poor.
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We know more about the biodiversity on land than in any other environment. But there is still much to be discovered. Scientists working in New Guinea are finding a lost world of unknown and rare species. The rainforests here are second only in size to the Amazon and many parts are uninhabited and inaccessible. Mammals once thought extinct are thriving in the remote mist-covered Foja mountains. New species of birds, frogs, butterflies and plants are revealing themselves to the scientists.
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