owners of infrastructural capital which yields more goods, such as a factory that produces automobiles just as an apple tree produces apples. Ecologists are teaming up with economists to measure and express values of the wealth of ecosystems as a way of finding solutions to the biodiversity crisis. Some researchers have attempted to place a dollar figure on ecosystem services such as the value that the Canadian boreal forest's contribution to global ecosystem services. If ecologically intact, the boreal forest has an estimated value of US$3.7 trillion. The boreal forest ecosystem is one of the planet's great atmospheric regulators and it stores more carbon than any other biome on the planet. The annual value for ecological services of the Boreal Forest is estimated at US$93.2 billion, or 2.5 greater than the annual value of resource extraction. The economic value of 17 ecosystem services for the entire biosphere (calculated in 1997) has an estimated average value of US$33 trillion per year. These ecological economic values are not currently included in calculations of national income accounts, the GDP and they have no price attributes because they exist mostly outside of the global markets. The loss of natural capital continues to accelerate and goes undetected or ignored by mainstream monetary analysis. Within the international community the basic principle is not controversial, although much uncertainty exists over how best to value different aspects of ecological health, natural capital and ecosystem services. Full-cost accounting, triple bottom line, measuring well-being and other proposals for accounting reform often include suggestions to measure an "ecological deficit" or "natural deficit" alongside a social and financial deficit. It is difficult to measure such a deficit without some agreement on methods of valuation and auditing of at least the global forms of natural capital (e.g. value of air, water, soil). All uses of the term currently differentiate natural from man-made or infrastructural capital in some way. Indicators adopted by United Nations Environment Programme's World Conservation Monitoring Centre and the Organisation for Economic Co-operation and Development (OECD) to measure natural biodiversity use the term in a slightly more specific way. According to the OECD, natural capital is “natural assets in their role of providing natural resource inputs and environmental services for economic production” and is “generally considered to comprise three principal categories: natural resources stocks, land, and ecosystems.” The concept of "natural capital" has also been used by the Biosphere 2 project,