"Humanity depends on healthy ecosystems: they support or improve our quality of life, and without them, the Earth would be uninhabitable. However, over the past 50 years, fast-growing demands for food, , water and other s have led to an unprecedented degradation of many ecosystem services so that their ability to sustain future generations can no longer be taken for granted. Therefore, reversing ecosystem degradation is one of the great challenges of sustainable development. This is by no means a trivial task as it requires action by all actors in society, including governments, industry and individuals. One of the difficulties is that, even if there was a universal commitment to sustainable development, it is still unclear what goods, services and activities are sustainable and how they could be identified."