Glossary of Terms and Concepts
adaptability refers to the degree to which adjustments are possible in practices, processes or structures of systems, to projected or actual changes in climate. Adaptation can be spontaneous or planned and can be carried out in response to or in anticipation of environmental changes.
adaptation is the adjustment to a new or altered situation. See also adaptation option.
adaptation options are policy options which adjust the physical environment or our ways of using it to reduce the consequences of an environmental risk, as opposed to preventive options.
aerosols are tiny particles in the atmosphere. Aerosols may be either natural or anthropogenic. Aerosols influence the energy balance of the earth system directly by reflecting radiation and indirectly by acting as cloud condensation nuclei, thereby affecting the reflectivity and other optical properties of clouds.
aggregation is the joining of more or less equivalent elements that exhibit mutual interaction. Aggregation can take place across different scale-dimensions, leading to different resolutions on these scales. The most relevant scale dimensions in Integrated Assessment Models are: temporal scale (e.g. diurnal; seasonal; annual), spatial scale (e.g. local; regional; continental; global), systemic scales (e.g. individual plants; ecosystems; terrestrial biosphere), and conditional scales (e.g. ecosystem internal variability; inter-ecosystem variability; global variability).
anthropogenic means man made; caused by human activity.
assessment is a process that connects knowledge and action regarding a problem. Assessment comprises the analysis and review of information derived from research for the purpose of helping someone in a position of responsibility to evaluate possible actions or think about a problem. Assessment usually does not mean doing new research. Assessment means assembling, summarizing, organizing, interpreting, and possibly reconciling pieces of existing knowledge, and communicating them so that they are relevant and helpful to an intelligent but inexpert policy-maker or other actor involved in the problem at hand.
biodiversity or "biological diversity" means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.
biogeophysical processes include all (relevant) biological, geological and physical processes and their coupled interactions in the Earth system or in a subsystem of the Earth system.
biome A complex of biotic community consisting of all of the plants and animals and their respective communities, including all of their successional phases, in a large geographic area.
biosphere The part of the Earth and the ocean and the atmosphere in which organisms live.
carbon dioxide is a gas of chemical formula CO2. It is created by animal life and by the oxidation of carbon compounds such as fossil fuels. Carbon dioxide is the most important anthropogenic greenhouse gas.
causal chain The causal chain of an environmental problem describes the cause-effect relationships between human activity and environmental change. In general, the causal chain of an environmental problem starts with socioeconomic drivers leading to economic activity and other practices, leading to emissions and other pressure on the environment leading to environmental changes, leading to physical impacts on societies and ecosystems, leading to socioeconomic impacts, eventually returning to cause changes in the socioeconomic drivers.
causal structure The total set of cause-effect relationships and feedback mechanisms in between, underlying a given problem. Usually the causal structure can be represented by a causal chain.
cellular automata A technique used in computer simulation modelling. Cellular automata (CA) were originally conceived by Ulam and von Neumann in the 1940s to provide a formal framework for investigating the behavior of complex, extended systems. CAs are dynamical systems in which space and time are discrete. A cellular automaton consists of a regular grid of cells, each of which can be in one of a finite number of k possible states, updated synchronously in discrete time steps according to a local, identical interaction rule. The state of a cell is determined by the previous states of a surrounding neighborhood of cells.
citizen panel Participatory technique in which a group of citizens meet more than once to discus an issue.
co2 carbon dioxide.
CO2-calculator A interactive computer program which produces an estimate of ones personal CO2 emission on the basis of ones lifestyle and behavior as measured by means of a interactive questionnaire. A CO2 calculator also provides insight into how one can change ones CO2 emission by changing ones life style and behavior. See for an example the Personal CO2 calculator at the website of the Climate and Environment in Alpine regions (CLEAR) project.
complexity Applied to systems which are not "simple", that is which behave like organisms or organisations, possessing some elements of structure, function, self-direction, etc. to a lesser or greater degree.
constructivism Social theories which postulate that problems are socially constructed (as opposed to realism, which states that problems exist independently of the perceptions humans have on them).
Cost-Benefit analysis is an economic technique applied to public decisionmaking that attempts to quantify in dollar terms the advantages (benefits) and disadvantages (costs) associated with a particular policy.
Cost-Benefit models are computational models that apply cost-benefit analysis for ex ante evaluation of environmental policy options.
cultural theory also known as "group grid theory". An explanatory scheme created by Mary Douglas and applied by herself and colleagues as Michael Thompson. It assumes two axes for describing social formations, "group" and "grid"; when these are at "high" and "low", they yield types described as "hierarchist", "egalitarian", " fatalist" and "individualist". Michael Thompson has added a fifth type, residing in the middle, called "hermit". In recent applications the "fatalist" has been eliminated from the scheme.
determinism A school of thought in which it is assumed that all physical events are caused by the sum total of past physical events. Determinism suggests that if there were a complete set of physical laws L and if one were to know the state of the entire universe at a given moment S0 then any future state could be derived at any future time Sn through S0 & L. Within this paradigm the practical applicability of the notion of determinism for forecasting is limited by chaotic behavior of complex systems and the practical impossibility to measure an initial state of the system under consideration.
deterministic In deterministic models (as opposed to stochastic models) all relationships are fixed and all parameters and variables of the model are single fixed numbers at any given time. Consequently, the model behavior, performance or operation due to a given input is uniquely determined.
discipline Specialized branch of science. Examples of disciplines are sociology, physics, economy, biology, anthropology, climatology, geography.
distributed models In a distributed model (as opposed to a lumped model) one or more independent variables denoting spatial position are involved, and the dependent variables and other model relationships depend on spatial position.
dynamic simulation model A simulation model whose behavior or performance is time dependent.
Earth System Model (ESM). Term used to refer to (bio)geophysical models used in global change research, such as GCM models, carbon cycle models etc. As opposed to Integrated Assessment Models, ESMs only represent the natural system and do not include representations of economic and social systems.
ecosystem means a dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit.
emission Pollution discharged into the atmosphere from smokestacks, other vents, and surface areas of commercial or industrial facilities; from residential chimneys; and from motor vehicle, locomotive, or aircraft exhausts.
endogenize To endogenize a given phenomenon (for instance technological change) in a model means to include that phenomenon in the model by including equations that govern it.
endogenous variables in a model are those variables that are considered inside a defined system boundary of a modelled system, as opposed to exogenous variables. For endogenous variables the time dependent behavior is part of the output of the model calculations. For exogenous variables the time dependent behavior is assumed (usually as one or more scenario's) and used as fixed input for the model calculations.
epistemology The theory of knowledge.
ESM Earth System Model.
exogenous Factors outside a defined system boundary (of a system under investigation) which influence the system behavior or performance are said to be exogenous.
extended facts the sorts of technical information that is legitimate in Post-Normal Science, including citizens' surveys, anecdotal information, and the results of investigative journalism.
extended peer communities participants in the quality assurance processes in Post-Normal Science, including all stakeholders seriously engaged in the management of the problem at hand.
extrapolation The inference of unknown data from know data, for instance future data from past data by analyzing trends and making assumptions.
facilitator A person who has the role to facilitate a structured group process (for instance participatory integrated assessment) in such a way that the aim of that group process will be met.
feedback A feedback process is a process whose input depends on its output, in other words, the output feeds back into the process as input. A feedback is said to be negative if it dampens the response of the system in which it is incorporated and positive if it amplifies the response of the system.
feedforward A feedforward process is a process whose output depends only on its input, and no feedback exists.
focus group Well established research technique applied since the 40's on the social sciences, marketing fields, evaluation and decision research. Generally, a group of 5 to 12 person is interviewed by a moderator on a specific focused subject. With the focus group technique the researcher can obtain at the same time information on various individuals together with the interactions amongst them. To a certain extend such artificial settings simulate real situations where people communicate among each other.
gaming is a simulation technique in which participants seek to achieve some agreed-upon objective within an established set of rules. For example, a management game, a policy game. Note: The objective may not be to compete, but to evaluate the participants, increase their knowledge concerning the simulated scenario, or achieve other goals.
GCM General Circulation Model.
General Circulation Model A computational model or representation of the earth's climate, used to forecast changes in climate or weather. Most GCMs concentrate on the circulation of the ocean or atmosphere ( the latter are often called "atmospheric general circulation models"). Atmospheric GCMs consist of equations that describe the atmosphere's basic dynamics, and include descriptions of its physical processes. Functions represent the conservation of energy, momentum, and mass, and calculate the distributions of wind, temperature, precipitation, and other indicators of climate as a result of emissions from human and natural sources. More elaborate climate models couple the atmospheric equations to others which describe the structure and dynamics of the ocean, and to other components of the climate system (land surface and ice). The most advanced models, three-dimensional GCMs with coupled representation of atmospheric and oceanic processes, can be run on only the largest and fastest supercomputers. Typically, GCMs are used to determine and describe potential climate changes that would result from a particular set of prescribed boundary conditions, after equilibrium is reached. It is more difficult to analyze dynamic results with these types of models, in which the boundary conditions are (more realistically) changing over time.
geophysical processes include all (relevant) geological and physical processes and their coupled interactions in the Earth system or in a subsystem of the Earth system.
GHG Greenhouse Gas.
global change refers to changes in the global environment that may alter the capacity of the Earth to sustain life. The environments include:
These environments interact in very complex ways so that it is difficult to define what is cause and what is effect, or to predict future changes. However, when there is change, it is certain that many things will change together. For example, if the climate becomes warmer glaciers become smaller, the ocean could rise and warm, and precipitation patterns may shift. Changes in local environments will cause changes in plant and animal life.
global warming An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases.
Global Warming Potential (GWP) The estimated warming effect over a period of time, resulting from a hypothetical instantaneous release of one kilogram of a given greenhouse gas in today's atmosphere. Each gas (CH4 , CFC-11, etc.) has a different GWP. The GWP is indexed against the warming effect of 1 kg of carbon dioxide (CO2). The GWP allows climate modellers to compare the relative radiative heating of various gases, taking into account the differing times that gases remain in the atmosphere and the degree to which they absorb infra red radiation.
greenhouse effect A popular term used to describe the roles of water vapor, carbon dioxide, and other trace gases in keeping the Earth's surface warmer than it would be otherwise. These "radiatively active" gases are relatively transparent to incoming short-wave radiation from the sun, but are relatively opaque to the long-wave (infrared) radiation emitted by the earth surface. The latter radiation, which would otherwise escape to space, is trapped by these gases within the lower levels of the atmosphere. The subsequent reradiation of some of the energy back to the surface maintains surface temperatures higher than they would be if the gases were absent. There is concern that increasing concentrations of greenhouse gases may enhance the greenhouse effect and cause global warming.
greenhouse gas are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and re-emit infrared radiation. When the atmospheric concentration of greenhouse gases increases, the heat-radiation balance of the atmosphere changes, which leads to an increase of the temperature at the earth surface. This effect is known as the enhanced greenhouse effect. The major man-made greenhouse gases are carbon dioxide (CO2), methane (CH4), (NO2), chloro-fluoro carbons (CFCs), Halocarbons (HFCs), perfluorocabons PFCs and sulfur hexafluoride (SF6).
group grid theory see cultural theory.
group moderator A group moderator has the role to guide a focus group discussion.
GWP Global Warming Potential.
habitat means the place or type of site where an organism or population naturally occurs.
hedging is a quantitative technique for the iterative handling of uncertainties. It is used, for instance, to deal with risks in finance and in corporate R&D decisions. For example, a given future scenario may be considered so probable that all decisions which are made assume that the forecast is correct. However, if these assumptions are wrong, there may be no flexibility to meet other outcomes. Thus, rather than solely developing a course of action for one particular future scenario, business strategic planners prefer to tailor a hedging strategy that will allow adaptation to a number of possible outcomes. Applied to climate change, it could for example be used by stakeholders from industry to reduce the risks of investing in energy technology, pending governmental measures on ecotax. Anticipating a range of measures from government to reduce greenhouse gases emissions, a branch of industry or a company could estimate the cost-effectiveness of investing or delaying investments in more advanced energy technology.
HTML Hyper Text Markup Language, a computer programming language used to write and publish pages on the World Wide Web. This glossary is written in HTML.
hyperspace. The parameter hyperspace of a model is the theoretical multidimensional space spanned up by all the parameters (imagine one axis for each parameter) of a model and the corresponding numeral domains in which the value of each parameter can lie.
IA Integrated Assessment.
IA focus group An IA focus group consists of a mixed group of citizens, who are provided with basic information, have access to one or several state of the art computer models during their deliberations and reach a collective conclusion, say a policy recommendation for the issue under consideration.
IAM Integrated Assessment Model
ICT Information and Communication Technology.
IEA Integrated Environmental Assessment
impact assessment is the systematic assessment of (potential) impacts of environmental changes on societies and ecosystems.
implementation is action to realize a strategy or fulfill a purpose. It is concerned with giving faithful effect to declarations, putting decisions into motion, selecting and carrying through a course of action intended to achieve identified (not necessarily announced) objectives.
inderterminacy is a category of uncertainty put forward by Brian Wynne. Indeterminacy refers to the open-endedness (both social and scientific) in the processes of environmental damage caused by human intervention. Indeterminacy introduces the idea that contingent social behavior also has to be included in the analytical and prescriptive framework. It also acknowledges the fact that many of the intellectual commitments which constitute our knowledge are not fully determined by empirical observations. The latter implies that scientific knowledge depends not only on its degree of fit with nature, but also on its correspondence with the social world and on its success in building and negotiating trust and credibility for the science.
Integrated Assessment (IA) can be defined as an interdisciplinary process of combining, interpreting and communicating knowledge from diverse scientific disciplines in such a way that the whole cause-effect chain of a problem can be evaluated from a synoptic perspective with two characteristics: (i) it should have added value compared to single disciplinary assessment; and (ii) it should provide useful information to decision makers.
Integrated Assessment Model (IAM) a computer simulation program representing a coupled natural system and a socio-economic system, modelling one or more cause-effect chains including feedback loops, and explicitly designed to serve as a tool to analyse policies in order to guide and inform the policy process, mostly by means of scenario analysis. This explicit policy purpose defines the difference between IAMs and Earth System Models (ESMs) such as Atmosphere Ocean General Circulation Models (GCMs) and geochemical models, which are designed primarily for scientific purposes. It should however be noted that ESMs such as GCMs could also be used (and in fact they are) to look at policy questions.
Integrated Environmental Assessment (IEA) is the subset of IAs concerned with environmental issues.
lumped models (as opposed to distributed models) are zero-dimensional. Their variables and modelling relationships do not depend on spatial position.
methane (CH4) is an important anthropogenic greenhouse gas. It is also the main component of natural gas. Methane is called "swamp gas" because it is produced by bacteria when organic matter decomposes under anoxic (oxygen-free) conditions, as in swampy land. Methane-producing bacteria are sensitive to oxygen, but they exist in habits such as animal digestive tracts, sanitary landfills, swamps, sludge, and other decaying organic matter, where the oxygen has already been removed by other bacteria. Methane is the only major greenhouse gas produced in greater amounts by developing countries than industrialized countries. Methane has a GWP of 21 (time horizon 100 years), which means that each ton methane emitted brings about an enhancement of the greenhouse effect comparable to the emission of 21 ton of CO2.
model a mathematical, physical or mental representation of a system - such as a global geochemical system, the climate system, an economic system , an agricultural operation, a petroleum refinery, or a temperate forest ecosystem - to explore its potential characteristics and behavior Many models (or system representations) are programmed as computer simulations of causes and effects within the system. These models are often used to test the effects of a change in system components on the overall performance of the system. For example, models of global or regional climate may be used to attempt to simulate the effects on temperature of a future change in the atmospheric concentration of greenhouse gases.
model moderator A model moderator has the role to present one or more computer models in an IA focus group in such a way that it is supportive for the IA participatory debate. The model moderator also guides the specific discussions during the computer interaction period. All other discussions are guided by the group moderator.
monetary valuation, also known as contingent valuation method is a survey-based economic method that is often used to quantify non-market values in dollar terms in order to quantify the benefits (or costs) of an environmental policy. It therefore directly asks people what they are willing to pay for a benefit an/or willing to receive in compensation for tolerating a cost through a survey or questionnaire. Personal valuations for increases or decreases in the quantity of some good are obtained contingent upon a hypothetical market. The aim is to elicit valuations or bids which are close to what would be revealed if an actual market existed.
monitoring Periodic or continuous surveillance or testing to determine (A) pollutant levels in various media or in humans, animals, and other living things and/or (B) the level of compliance with statutory requirements.
Monte Carlo is a statistical technique for stochastic model-calculations. It's purpose is to trace out the structure of the distributions of model output. In it's simplest form this distribution is mapped by calculating the deterministic results (realizations) for a large number of random draws from the individual distribution functions of input data and parameters of the model. To reduce the required number of model runs needed to get sufficient information about the distribution in the outcome (mainly to save computation time), advanced sampling methods have been designed. Latin Hyper Cube sampling is the most efficient method currently available. It makes use of stratification in the sampling of individual parameters and pre-existing information about correlations between input variables.
multi-criteria decision analysis a method of formalising issues for decision, using both "hard" and "soft" indicators, not intended to yield an optimum solution but rather clarifying positions and coalitions.
nonlinear system A nonlinear system is a system whose time evolution equations are nonlinear; that is, the dynamical variables describing the properties of the system (for example, position, velocity, acceleration, pressure, etc.) appear in the equations in nonlinear form.
no-regrets policy Policy based on the idea that the problem of global climate change is linked to other critically important problems of environment and development. The combined risks are serious enough, and the eventual benefits of action great enough, to require urgent and bold initiatives, even if they impose a substantial immediate cost. Advocates of this policy argue that strong action will lead to a "no regrets" outcome, even if climate change turns out to be an exaggerated fear. The benefits will include experimentation, foresight, and cost-effective prevention. Moreover, say the proponents, early actions offer the prospective extra benefit of learning through experience: of gaining better information about the benefits and costs of action through our first steps.
optimization models. Class of Integrated Assessment Models which are designed to determine the optimal level of greenhouse gas emissions reductions from abatement cost and damage functions.
ozone A molecule made up of three atoms of oxygen. In the stratosphere, it occurs naturally and it provides a protective layer shielding the Earth from ultraviolet radiation and subsequent harmful health effects on humans and the environment. In the troposphere, it is a chemical oxidant and major component of photochemical smog.
parameter A quantity related to one or more variables in such a way that it remains constant for any specified set of values of the variable or variables.
parameterize Parametrization is the method of incorporating a process by representation as a simplified function of some other fully resolved variables, without explicitly considering the details of the process.
PIA Participatory Integrated Assessment.
portability is the extent to which computer software can be run on different computer platforms or under different operating systems.
post-normal science is the methodology that is appropriate when "facts are uncertain, values in dispute, stakes high and decisions urgent". It is appropriate when either "systems uncertainties" or "decision stakes" are high. Click here for a brief introduction to post-normal science.
preventive options are policy options directed at the causes of a environmental problem rather than at the mitigation of the consequences as adaptation options do.
probabilistic. Based on the notion of probabilities.
problem structuring an approach to analysis and decision making which assumes that participants do not have clarity on their ends and means, and provides appropriate conceptual structures. It is a part of "soft systems methodology".
process-detail is the extent to which equations that govern variables in a model reflect the actual detailed mechanisms of the processes in the real world which they represent. The opposite of high process detail is formed by highly aggregated parameterized representations.
reflexivity applied by social theorists (Giddens, Beck) to refer EITHER to the enhanced self-awareness of people in advanced modern society, and hence of institutions to be more self-conscious in their work; OR to the tendency of modern industry to produce unexpected, unwanted effects in Nature which reflect back on society. ALSO used in "reflexive complex systems", those where sub-systems ("holons") have purposes and awareness of their own.
relativism school of thought in which all knowledge is seen as socially produced and therefore distorted by social interests. Since all knowledge is thus distorted, there are no independent standards of truth.
reservoir means a component or components of the climate system where a greenhouse gas or a precursor of a greenhouse gas is stored.
scenario A plausible description of how the future may develop, based on a coherent and internally consistent set of assumptions about key relationships and driving forces (e.g., rate of technology changes, prices). Note that scenarios are neither predictions nor forecasts. The results of scenarios (unlike forecasts) depend on the boundary conditions of the scenario.
simulation (l) A model that behaves or operates like a given system when provided a set of controlled inputs. A model that represents some aspect of the simuland's behavior. (2) The process of developing or using a model as in (1). (3) An implementation of a special kind of model that represents at least some key internal elements of a system and describes how those elements interact over time.
sink means any process, activity or mechanism which removes a pollutant (for instance a greenhouse gas, an aerosol or a precursor of a greenhouse gas) from a reservoir (for instance the atmosphere, or the ocean). A carbon sink, for example, might be the ocean (which absorbs and holds carbon from other reservoirs of the carbon cycle) or photosynthesis (which converts atmospheric carbon into plant material). Sinks are a fundamental factor in the ongoing balance which determines the concentration of every greenhouse gas in the atmosphere. If the sink is greater than the sources of a gas, its concentration in the atmosphere will decrease; if the source is greater than the sink, the concentration will increase.
source means any process or activity which releases a pollutant (for instance a greenhouse gas, an aerosol or a precursor of a greenhouse gas) into a reservoir (for instance the atmosphere or the ocean. See also sink.
stakeholders are those actors who are directly or indirectly affected by a issue and who could affect the outcome of a decision making process regarding that issue or are affected by it.
steady A system is said to be in steady state if it's state is constant and does not vary with time. A model is said to be static or steady state if it's behavior is constant and does not vary with time, as opposed to dynamic or unsteady models.
stochastic In stochastic models (as opposed to deterministic models), the parameters and variables are represented by probability distribution functions. Consequently, the model behavior, performance, or operation is probabilistic.
stratosphere That layer of the atmosphere extending from the tropopause (8 to 15 km altitude) to about 50 km. The ozone layer which shields the Earth from ultraviolet radiation is located in the stratosphere.
sustainability A term used in, for example agriculture and forestry, to designate management methods designed to ensure that the productive yield of an ecosystem is maintained undiminished for the benefit of future generations.
sustainable development According to the WCED, this is "development that meets the needs of the present without compromising the ability of future generations to meet their own needs." Sustainable development implies economic growth together with the protection of environmental quality, each reinforcing the other. The essence of this form of development is a stable relationship between human activities and the natural world, which does not diminish the prospects for future generations to enjoy a quality of life at least as good as our own. Many observers believe that participatory democracy, undominated by vested interests, is a prerequisite for achieving sustainable development.
systems analyses an approach to problem-solving, developed in WW-II, which looks at the aggregate behavior and selects strategically significantly problems to solve, rather than attempting complete scientific knowledge of all elements.
tacit knowledge a sort of knowing, elaborated by Michael Polanyi, which involves only a peripheral awareness, and relates to the implicit framework in which knowing and acting takes place.
transparency is the degree to which a model is transparent.
transparent A model is said to be transparent if all key assumptions that underlie it are accessible and understandable for the user.
troposphere The inner layer of the atmosphere below about 15 km, within which there is normally a steady decrease of temperature with increasing altitude. Nearly all clouds form and weather conditions manifest themselves within this region, and its thermal structure is caused primarily by the heating of the Earth's surface by solar radiation, followed by heat transfer by turbulent mixing and convection.
uncertainty-based models are models that explicitly take into account uncertainty, usually by representing all parameters of the model by probability density functions.
unsteady A model is said to be unsteady or dynamic if its behavior varies with time, as opposed to steady of static models.
validation Comparing a model's predictions with observations of the real system, in order to test the reliability and accuracy of the model. The most obvious way to test a model is to use it to analyze past events, and then see whether its simulated prediction "came true," or how close it was to being correct.
Value Of a Statistical Life the Willingness to Pay (WTP) for a small change in the risk of death divided by the magnitude of that risk change.
variability When used in reference to climate, variability refers to the tendency of conditions to vary around some reference point (such as the tendency of the temperature to deviate from some average)
vulnarability defines the extent to which climate change may damage or harm a system. It depends not only on a system's sensitivity, but also on its ability to adapt to new climatic conditions. For instance, the consequences of sea-level rise or changes in the distribution of malaria vectors or other climate-zone related diseases are highly determined by the sensitivity, adaptability, and vulnerability of the local systems. These are in turn affected by parameters such as welfare of a local society or fitness of a local population. An industrialized country that has enough money for a good coastal defense system will have less exposure to future sea level rise than a developing country that has no money for adequate coastal defense.
Willingness to Pay (WTP) A measure used to express non-market values in monetary units (dollars). The WTP is measured by directly asking people what they are willing to pay for a benefit an/or willing to receive in compensation for tolerating a cost through a survey or questionnaire. Personal valuations for increases or decreases in the quantity of some good are obtained contingent upon a hypothetical market. The aim is to elicit valuations or bids which are close to what would be revealed if an actual market existed.
This page was last updated at: 30 July 1999