Ecosystem services represent the myriad of benefits that society receives from nature. Nature provides products such as clean air and water, food, fiber, fuel, and soils; in less tangible ways nature provides recreational, educational, spiritual, and aesthetic resources; and, nature regulates systems that can then be relied upon by people including nutrient cycling, climate regulation, carbon storage, flood control, wildlife and game habitat, pollination, and photosynthesis, among many others. These resources are described as natural capital and are considered as fundamental to the economy as financial, produced, social, and human capital.
(CC Image (right) by Betsyfailey (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons).
Ecological economists make the case that natural capital should be calculated in GDP accounting; where it is diminished, it reduces GDP; where it is protected, it contributes positively to GDP. Noted expert in natural capital, Paul Hawken stated at a commencement speech in 2009 that "At present, we are stealing the future, selling it in the present, and calling it Gross Domestic Product," which implies that future residents will find depleted stocks of natural capital and fewer of the benefits that we receive from them today.