Ecosystem valuation is an economic process which assigns a value (either monetary, biophysical, or other) to an ecosystem and/or its ecosystem services. By quantifying, for example, the human welfare benefits of a forest to reduce flooding and erosion while sequestering carbon, providing habitat for endangered species, and absorbing harmful chemicals, such monetization ideally provides a tool for policy-makers and conservationists to evaluate management impacts and compare a cost-benefit analysis of potential policies. However, such valuations are estimates, and involve the inherent quantitative uncertainty and philosophical debate of evaluating a range non-market costs and benefits. History and Economic Model History Cost-benefit analyses and the generation of market value have existed within the economic literature for centuries. However, in 1997, Robert Costanza, Distinguished University Professor of sustainability at Portland State University, Oregon, was the first to estimate the worldwide worth of ecosystem services—bringing new attention to the field of ecosystem valuation. He and his colleagues calculated that such services were worth $33 trillion annually ($44 trillion present dollars). Despite Costanza's fanfare, the World Bank, three decades later, that "the benefits provided by natural ecosystems are both widely recognized and poorly understood.” Citing the importance of such knowledge to informed policy-making, in 2007, Environmental Ministers from the G8 + 5 nations agreed to both publicly call for and begin to undertake the calculation of global ecosystem benefits, conservation costs, and the opportunity costs of developing such ecosystems. The resulting watershed initiative and ongoing project is The Economics of Ecosystems and Biodiversity (TEEB). In the United States, the President's Council on Science and Technology suggested in 2011 that the “U.S. government should institute and fund a Quadrennial Ecosystems Services Trends (QuEST) Assessment” that studying trends in ecosystem performance, quality, and value. Economic Models: Values, Costs, and Value Methodology Ecosystem valuation attempts to capture the range of benefits and costs contained within a complicated natural web with a range of economic methodologies. Ecological systems provide four general categories of services: provisioning (e.g. fish to eat, timber to sell), regulatory, supporting, and cultural (e.g. ecosystems supporting indigenous gathering techniques, or supplies for traditional clothing). See Figure 1. for a mangrove-specific example of this complex subject. These four types of services can then provide two basic categories of value: the use and non-use categories. Environmental economists have further separated categorizes for which individuals are willing to pay: Direct-use value. The simplest form of ecosystem valuation for orthodox