The ecological processes of natural ecosystems provide humanity with a large and important range of free services on which we depend. These include: maintaining the quality of the atmosphere (which helps regulate the climate); improving water quality, controlling water cycles, including reducing the likelihood of serious flooding and droughts; protecting coastal areas for the conservation and generation of coral reef and dune systems; generating and conserving fertile soils; controlling crop pests and disease vectors; facilitating the pollination of many crops; directly providing food from aquatic and terrestrial environments and the maintenance of a vast "genetic library" from which man has extracted the foundations of civilization in the form of crops, domesticated animals, medicines and industrial products.

For hundreds of years mankind did not pay much heed to the generation of these services, which were assumed to be inexhaustible. Now it is clear that the continued provision of these services requires us to maintain ecosystems in peak condition.