It is understood to contain both a quantitative dimension (e.g. the quantity of output produced with a given input of natural resources) and a qualitative dimension (e.g. the environmental impacts per unit of output produced with a given natural resource input). However, unless such improvements outweigh economic growth, there is a risk that the associated negative environmental impacts might increase. Protecting and managing the natural resource base cannot, therefore, rely on improvements in resource productivity alone, it will also be necessary to de-link economic growth from environmental pressures (Box 3.2).