Why should we care?

Humans are greeting this “bio-armageddon” with little more than a “yawn and shrug”, says National Geographic’s Simon Worrall. “One fewer bat species? I’ve got my mortgage to pay.”

But the loss of a species has profound effects on the ecosystems on which human life depends, argues Dr Nisha Owen, from the Zoological Society of London.

These systems “provide us with clean air, clean water and the food that we eat”, she says. Losing even a single plant or animal species could also affect us in ways we can’t predict.

“You have one tree in Borneo with a thousand species of insects. What do those insects do for us? We don’t know,” said filmmaker and explorer Benedict Allen during a debate hosted by Nat Geo WILD and The Week. (To see the debate visit Theweek.co.uk/inthewild) “That,” said Allen, “is the most terrifying thing.”

Joel Sartore was forced to confront similar questions while filming Photo Ark in Madagascar, where deforestation is a serious problem. “The forests get cut because people need to eat,” he says – but once they’ve cut down trees to plant crops or make charcoal, “the rains come and it washes everything away. It totally erodes the surface of the earth.”

The resulting habitat loss has a dramatic effect on forest-dwelling species and the ecosystems they support. “You can’t cut all these trees down and have a stable environment,” Sartore says. “The world’s ending, a little bit at a time.”