Despite humanity’s many technological advances, we can only manage a well-informed guess at the true extent of life on Earth: 8.7 million species, according to the most commonly cited figure, with other estimates ranging between 5.3 million and one trillion.
There is greater certainty about the decline of biodiversity that human behaviour is driving, with species dying off as much as 1,000 times more frequently than before the arrival of humans 60m years ago, as one study suggests.
