While scientists and
environmentalists have discussed ecosystem services implicitly for decades, the
Millennium Ecosystem Assessment (MA) in the early 2000s popularized this concept.
[1] There, ecosystem services are grouped into four broad categories: provisioning, such as the production of food and water; regulating, such as the control of climate and disease; supporting, such as
nutrient cycles and
oxygen production; and cultural, such as spiritual and recreational benefits. To help inform
decision-makers, many ecosystem services are being assigned economic values.