$33 trillion according to one study. But is it possible to put a price on nature? Is it immoral to even try? What would be the point of trying to put a cash number against 'services' nature provides? Would such an approach devalue nature, or provide a powerful tool to defend it?
For many people, birds contribute hugely to their quality of life: simple birdsong uplifts people. We see or hear them every day, unlike tigers or elephants that we contribute millions of pounds to charities to protect even though most of us will never see them. So how much value do birds add to our lives?