"Natural capital is another term for the stock of renewable and non-renewable natural resources on earth (e.g., plants, animals, air, water, soils, minerals) that combine to yield a flow of benefits or 'services' to people." - The Capitals Coalition
"Natural capital accounting (NCA), which is part of broader wealth accounting, integrates natural resources, economic valuation and analysis, providing a better understanding of development progress and its impacts on society and environment than standard measures such as Gross Domestic Product (GDP)." - The World Bank
"Natural capital accounting is a tool to measure the changes in the stock and condition of natural capital (ecosystems) at a variety of scales and to integrate the flow and value of ecosystem services into accounting and reporting systems in a standard way." - The European Commission