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Authors: Michael Watts

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entropy
A measure of the amount of uncer tainty in a probability distribution or a system subject to constraints. The term originated in thermodynamics, but has been used in a wide variety of contexts, notably in informa tion theory and as the basis for entropy maximizing models of spatial interaction. (NEW PARAGRAPH) The concepts of macrostate and microstate are central to entropy analysis. Consider the distribution of 100 people into 10 regions: individual B to region six, individual K to region four and so on. A macrostate is an aggre gate frequency distribution of people across regions. Several different microstates may cor respond to or give rise to the same macrostate: different individuals go to different regions, but the frequency distributions are the same. Entropy measures the relationship between a macrostate and the possible microstates that correspond to it. At one extreme, one macro state (all 100 people in one region) has only one associated microstate, whereas the macro state with 10 people in each region corres ponds to a large number of different microstates. The number of microstates corre sponding to a macrostate is denoted here by W and finding the entropy measure is a com binatorial calculation, given by (NEW PARAGRAPH) W = N1/JI m!, i (NEW PARAGRAPH) the factorial of the total number of individuals N, divided by the product of the factorials for each ni (the number in each region). An alter native, but equivalent, measure is that used in information theory. Lwh (NEW PARAGRAPH) Sugges
entropy-maximizing models
Statistical mo deLs for identifying the ?most likely? spatial allocation pattern in a system subject to con straints. The approach was introduced into geo graphical modelling by A.G. Wilson (1967) as the basis for a more rigorous interpretation ofthe gravity modeL, and has been extensively used since for spatiaL interaction modelling in urban regions and for modelling inter regional flows of traffic and commodities. It is based on the concept of eNtropy, a measure of the uncer tainty or ?likelihood? in a probability distribu tion. A journey to work model illustrates the method. For a city divided into k zones, we wish to calculate the best estimate ofinterzonal com muting flows Tij, without knowing the detailed information of each individual movement. Assume that there are N total commuters. Any specific trip distribution pattern Tij, known as a ?macrostate? (see eNtropy), can arise from many different sets of individual commuting move ments, or ?microstates?, and entropy measures the number of different microstates that can give rise to a particular macrostate. In the absence of detailed microstate data, we assume that each microstate is equally probable, and that the macrostate with the maximum entropy value is the most probable or most likely overall pat tern. Additional information is also normally available, notably the number of commuters ori ginatingfrom each zone, the total number of jobs available in each zone, and estimates ofthe aver age or total travel expenditure for the city, C (usually based on survey data). The entropy maximizing method then consists of maximizing the entropy measure subject to these constraints. (NEW PARAGRAPH) This maximization is a non linear optimization problem, and must be solved by iterative search methods. These models not only fit empirical trip distributions well, but also facilitate easy calculation of the effects of new housing or jobs (by altering the constraints), and so have been widely used in more general urban models. Wilson and his Leeds colleagues have extended the model in many ways, making it dynamic, linking it to industrial and urban Location the ory, and including several types of disaggrega tion (e.g. by mode of travel). lwh (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Gould (1972); Thomas and Huggett (1980); Wilson (1970). (NEW PARAGRAPH)
environmental audit
Environmental audit ing originated in the 1970s as a management tool to evaluate how well a corporation was complying with the complex array of environ mental legislation that was emerging as a result of the eNviroNmeNtAL movement. It is an important part of environmental manage ment systems (EMS). (NEW PARAGRAPH) Environmental audits are an ?official exam ination and verification ofaccounts and records to assess how close the situation comes to meet ing a set requirement? (Thomas, 2005, p. 236). They are a one off collection of data, and there fore differ from ongoing monitoring activities. Environmental audits may be internal to a cor poration, produced externally, undertaken vol untarily or to fulfil legal requirements, and may check compliance with regulations or focus on a company?s systems to achieve and maintain compliance (de Moor and de Beelde, 2005). Environmental audits may be undertaken for governments, aid agencies, financial institu tions and community groups. Internal environ mental auditing helps companies meet regulations and their own environmental goals in a cost effective manner. Mandatory, external auditing verifies and encourages compliance with environmental regulations. Who under takes the environmental audit and who has access to the resulting document are questions about the regulation of industry and commerce. Environmental auditing is situated within larger debates about how to achieve and main tain high environmental quality. pm (NEW PARAGRAPH)
environmental determinism
A type of reasoning that holds that the character and form of a society, cuLture or body can be explained by the physical conditions within which it has developed. Determinism is a form of explanation that finds no place for other factors, outside forces or random features. All creativity and productivity is assigned to first causes, in this case to environmental condi tions. Social and human diversity is explain able, this doctrine would hold, solely in terms of the environments within which they develop. In this sense there is a strong assump tion that nature and cuLture exist as a dual ism, and that cultures are shaped by Nature. While it is accepted that cultures interact with environments, and may alter them, it is never theless argued that the conditions for doing so are shaped by the larger environment. There are two major forms of critique of environ mental determinism. The first is a form of humanism, arguing that far from being reduced to their physical conditions, human beings can transcend those conditions through, variously, ingenuity, spirit, technol ogy and social organization. However, such arguments tend to reproduce rather than over come the Nature/Culture dualism, and can result in forms of voluntarism and ideaLism. The second is a more materiaList argument, suggesting that people and environments con tinuously evolve in relation to one another, and in doing so necessarily co produce one another. In these versions, determinism is debunked not because of any transcendent human capacity, or any mysterious element, but through the sheer randomness of matters in relation. (NEW PARAGRAPH) Environmental determinism has a long and varied history, from the ancient Greeks (notably Aristotle?s climatic zones), the Renaissance (notably Montesquieu?s Heaven and Earth), to post Darwinian writers (Glacken, 1967). From the late nineteenth to the mid twentieth century, it is often argued that geography was complicit, through its environmental determinism, with a north European supremacism that linked human ?achievement? and deveLopment to environ mental conditions (Livingstone, 1992). Friedrich Ratzel in Germany and Ellen C. Semple in the United States perhaps best captured this geographical tradition. Yet even here, and certainly in later writings of other environmental determinists, the arguments were rarely as clear cut as might be supposed. O Tuathail (1992) demonstrates Halford Mackinder?s partial fouNDationaLism, where in he ceded to humans the power to transcend formative environmental conditions. Twentieth century schools sought to blur the lines of explanation, giving rise to such terms as possibiLism and probabiLism. The latter terms are most often associated with the French (NEW PARAGRAPH) school of geography, most famously Paul Vidal de la Blache. Yet, rather like the berKeLey schooL and later forms of Marxist and Russian geography, the notion that nature conditioned subsequent actions remained. Despite this recurrent naturaLism and its essentialist and foundationaL tones, many of these works repay close scrutiny in a discip line that has been all too keen to leave non human matters aside. The task is now to avoid any lurch to the cultural in an attempt to leave environmental determinism behind once and for all, and instead to return to the indeter minate question of how it is that human and non human histories and geographies are intertwined. Finally, how to account for the longevity of this form of explanation is itself a complex question, one that would require attention to processes as varied as scientific authority and forms of reasoning (see science), coLoniaLism and academic discip line building. sjh (NEW PARAGRAPH) Suggested reading (NEW PARAGRAPH) Livingstone (1992). (NEW PARAGRAPH)
environmental economics
A branch of market based economics that advocates applying economic instruments to solve envir onmental problems. Although environmental economics can be traced to earlier work in the 1920s, it emerged at the same time as the environmentaL movement in the 1960s. At that time most academic, government and corporate economists were insensitive to the environmental impacts of economic growth. Environmental economists claim that the eco nomic system, when the wrong price signals are given, is a major cause of environmental problems. The main solution pursued by environmental economists is to send the right price signals via market mechanisms. This approach is now among the most dominant approaches to diagnosing and managing envir onmental problems in developed countries. It is increasingly popular given the pro market orientation of neo LiberaLism that exists glob ally and dominates in particular countries. (NEW PARAGRAPH) Environmental economics is closely associ ated with neo cLassicaL economics and resource management. It expands the reach of the market to factor in what environmental economists label an ?externaLity?, thereby changing the pricing signals for existing mar ket transactions or creating new commodities and markets. water trading, carbon credits (see gLobaL warming) and pollution credits are all examples of environmental economics applied to environmental issues. Bosetti and Pearce (2003) demonstrate the application of environmental economics to conflicts between fishing and seal conservation interests in south west England. (NEW PARAGRAPH) Geographers have been concerned about the pricing of the environment, and particu larly about how monetary values are attached to environmental ?goods? and ?services? through contingent valuation. Pricing approaches include willingness to pay (WTP) and willingness to accept compensation (either WTA or WAC). Clark, Burgess and Harrison (2000) highlight the weaknesses in contingent valuation, particularly a lack of understanding by many respondents of what they were valuing and how this information would be used. This is crucial because envir onmental economists rely on approaches that translate ?human preferences? into monetary values in order to create pricing signals and operate a market (see Thampapillai, 2002). (NEW PARAGRAPH) Environmental economics has been subject to considerable criticism. Some critics believe that pollution taxes are licences to pollute, and do not relate to the absorptive capacities of the environment or ethical questions about per petuating pollution. It is seen as reformist, or tinkering, with markets. At best, it reduces the worst excesses of market forces, but it also justifies some environmental damage and it perpetuates market expansion through the commodification process. It does not call for an economic overhaul, as in the tradition of the more radical ecological economics approach, and it does not treat the environ ment as having existence in its own right. However, the approach is increasingly influen tial, and so it cannot be ignored. pm (NEW PARAGRAPH)
environmental hazard
Sometimes known as a ?natural hazard?, or popularly as a ?natural disaster?, this item generally refers to geophys ical events such as earthquakes, tsunamis, vol canoes, bushfires, drought, flooding, lightning and high winds that can potentially cause major economic damage and physical injury or death. Such events, for example earth quakes, will have differing impacts depending on their magnitude and the character of the affected area (e.g. a heavily populated area versus a sparsely settled area). Given the long term involvement of humans as part of nature, a detailed analysis of so called ?envir onmental hazards? often reveals significant human input (see hazard). The characteristics of an environmental hazard are that it was not directly caused by humans, it directly affects humans (unlike an extreme natural event in nature that does not directly affect humans) and it is often accompanied by a violent release of energy. The United Nations declared the 1990s the ?International Decade for Natural Disaster Reduction? (Mauro, 1995). The use of the terminology ?natural? perpetuates the false perception that humans play no part in these disasters. Geographical research in the 1990s increasingly stressed ?disaster? rather than ?hazard?, thereby empha sizing the social and cultural issues and the humanitarian response needed when disaster occurs (White, Kates and Burton, 2001). (NEW PARAGRAPH) The distinction between environmental hazard and a human made hazard has blurred. It can only be maintained if humans are seen as being separate from nature, rather than a species that has been part of nature for thou sands of years. Today we experience physical events, the impacts of which are influenced by the actions of humans and other species, which in turn influence the character of future physical events. (NEW PARAGRAPH) Work in the United States on hazards and disasters emerged in the context of the nuclear threat and the cold war. Geographical research found that despite heavy spending on dams, losses due to floods were increasing. This environmental hazard research was cri tiqued from Marxist geography. Smith and O?Keefe (1980) claimed that geographers in the tradition of positivism displayed three major ways of dealing with nature, and dem onstrated this through ?natural hazards? research. The three major approaches are nature being seen as separate from human activity; where nature is seen as neutral but becomes hazardous when it intersects with human activity; or where humans are dis solved into nature. The first approach focuses attention on ?natural causes? of disasters, rather than human vulnerability. The second approach is seen as a technocratic agenda to control nature. The third approach is seen as Malthusian (see Malthusian model), because it blames the victims. (NEW PARAGRAPH) Today, many geographers question a ?nat ural hazard? and highlight the difference between a natural event (e.g. drought, which may be partly caused by human activity) and the consequences (famine). These differences are usually attributed to the structure and per formance of social systems. Recent Deleuzian inspired work by Nigel Clark (2005b) expands the notion of systems by considering the Earth as an open system when exploring conceptions of nature, risk society, and the construction (NEW PARAGRAPH) of catastrophic events and their counterpoint, the notion of order in nature. pm (NEW PARAGRAPH)
BOOK: The Dictionary of Human Geography
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