“They report today in the US journal Science that the wilderness converted to human use each year actually costs economies $250bn a year, every year.
Put another way, it would cost the world $45bn to extend and effectively protect threatened areas of temperate and tropical forest, mangrove swamps, coral reefs and so on. But in return, these global reserves would supply humans with at least $4,400bn in "goods and services". This is a benefit-cost ratio of around 100-1. And that, they say, is a low estimate of the likely benefits of better and more sustained conservation.”