The basis for this study relies on theories related to three important development trends. First, there are theories related to environmental and energy transitions. We apply urban environmental transition theory to energy transitions. Second, we briefly explore the drivers of transitions. We argue that transitions are affected by a number of different factors, both directly and indirectly. Third, we focus on how these drivers have changed over the past century and most intensely over the past few decades. We claim that changes in drivers have time- and space-related effects. These effects shift human/natural interactions and therefore have significant impacts on environmental and energy transitions. We describe the effects and various time/space concepts that provide ways in which to understand the unique circumstances experienced by developing economies today.
What are the environmental challenges that cities undergo as they develop? Urban environmental transition theory provides a powerful tool for addressing this question (see, for example, McGranahan et al. 2001; McGranahan and Songsore 1994). Rather than the simple notion described by the environmental Kuznet's curve (EKC) of an 'inverted U'-shaped function relating environmental degradation to rising incomes (see, for example, Grossman and Krueger 1995), the urban environmental transition identifies layers of changes in the relationship between affluence and urban environmental burdens. The claims are based upon an empirical tendency for urban environmental burdens to be more dispersed and delayed in higher income cities than in lower income cities. In summary, the theory suggests that in poor cities, environmental challenges are localized, immediate and health threatening. In middle-income, rapidly developing cities, environmental burdens are citywide or regional, somewhat more delayed in their impacts and a threat to both health and ecological sustainability. In affluent or high income cities, environmental burdens are global, intergenerational and primarily a threat to sustainability.
The theory includes the addition of geographic and temporal scale to notions of urban sustainability and as such questions whether urban sustainability has been achieved by any city in the world. Essentially, by including the differences in environmental burdens and the scale at which the impacts are felt, the theory predicts that at different levels of income different problems dominate, but that no city has addressed all issues.
Historical urban research that associates urban growth and environmental impacts suggests that in the past, urban environmental burdens were addressed by simply dispersing the associated harms to greater scales. Urban environmental historians in the USA have also noticed the change in environmental burdens over time. Melosi (2000) identifies how environmental challenges associated with water supply, sanitation and solid waste management have undergone a series of changes over time and have increasingly spread to wider geographical spaces. Tarr (1996) suggests that urban environmental history can be fundamentally characterized as the search for larger and larger sinks we used to unload waste streams. Both these historians have identified changes in type and geographic and temporal aspects of environmental burdens that are comparable to urban environmental transition theory.
Those working in the area of energy have also identified historical transitions at both the macro-level for developed countries (Elias and Victor 2005; Gruebler 1998; Gruebler 2004; Marchetti 1988; Nakicenovic 1988; Smil 1994) and for developing countries at the household level (Elias and Victor 2005; Smith 1987; Victor and Victor 2002). The first transition was associated with the Neolithic revolution and energy technologies that are associated with the shift from hunting and gathering to agriculture (Diamond 1997). It was not until the industrial revolution that societies turned from biomass and animate power supplemented with wind and water power as supplies to fossil fuels (Gruebler 1998). The industrial revolution that signed the start of a trend of sequential changes in primary energy supplies with increasingly higher energy densities; from coal to petroleum to natural gas and nuclear power. With each change in energy source came a reorganization of economic activity and new environmental consequences.
Urban environmental transition theory has been applied to different contexts, including economies in rapidly developing Asia (Bai and Imura 2000; Webster 1995). These applications have either simply described differences between cities of different income levels or included changes in the speed of transitions. Bai and Imura (2000), for example, insist that environmental transitions can be observed within Asian cities and that they have occurred in sequence, from traditional to industrial, to modern environmental challenges, albeit in a faster manner than previously experienced. These previous studies have missed important aspects of the current development context. That is, how environmental challenges within rapidly developing countries are emerging at lower levels of income and in a more overlapping or simultaneous fashion (Marcotullio 2005b; Marcotullio and Lee 2003). At the household level, recent studies identify few societies experiencing a regular and consistent path from traditional fuel consumption to the use of electricity and other modern fuels (Barnes et al. 2005).
What might be the influences affecting transitions and why would they change over time? Many emphasize the importance of income in influencing transitions (Leach 1992; Pachauri 2004). The authors of the urban environmental transition theory argue that affluence is only one of many factors explaining these shifts.3 Elias and Victor (2005) suggest that climate, resource endowments, and distance to markets are non-income related aspects that force energy transitions. We argue that there are many more influences on transitions at the macro-level, as will be described in the next section. Unfortunately, as many of these influences were overshadowed by a focus on economic growth, their affects have been largely ignored.
3.2.2 Drivers of urban environmental transition change
There are potentially many drivers of change that help to produce the patterns identified in urban environmental transition theory. 'Drivers' can include any natural or human-induced
3McGranahan et al. (2001) stress that transitions do not reflect human preferences at different levels of economic development. Rather, they suggest that transitions reflect social inequities and the failure to accommodate human preferences, preferences that are not easily represented and negotiated within current socio-economic and political systems.
factors that cause a change in the environment. Given the large number of factors in urban environmental change, a useful distinction between different types include those that have 'direct' (where the impact between the drivers and the impact can be measured) and those that have 'indirect' (where the impact between the drivers and the change cannot be measured) influence.
We can see the effect of these different drivers on transitions within cities in the developed world in urban environmental history. For example, the rapid population, economic and physical expansion of New York City after the completion of the Erie Canal, low levels of technology adoption in water supply, miasma disease theory, health and fires crises, public interest in wresting control of water supply from the private sector and elite interest in making the city one of the leading cities within the then growing USA combined to promote development of the Croton Water Supply system cities in the nation. Given the intensity of these drivers, New York City was one of the first, located several miles outside the city, around the 1830s-1840s to implement a comprehensive water supply system (and even went out of the city to get water) (Burrows and Wallace 1999). The centralization of water and the importance of large infrastructure projects associated with water supply became a 'path dependent' outcome of development in this arena for many US cities (Melosi 2000). Other cities in the nation soon followed suit, but to their later dismay made decisions to extract water from nearby surface water bodies (see, for example, Philadelphia and Chicago).
This important transition ushered in a new era of environmental change and facilitated the growth of cities in the USA. It was the beginning of the industrial revolution in the country, and rapid economic, social and political changes occurred. The rapid increases in water use, the failure of the contemporary drainage system, the threat of disease within an increasingly concentrated population, the ability of the political machine to use public works for rent seeking purposes, among other factors, prompted the development of the sanitation system in New York City around the 1870s-1880s. Importantly, the 'unintended consequences' of developing a water supply system were an important force in the development of a sewage system. That is, once large amounts of water were brought into the city, a new crisis arose as to how to get the increasingly larger volume of used water out of the city. Hence, across the USA, cities' sanitation systems were developed after water supply systems (Tarr 1999).
It was not until the turn of the century (a full 50 years after water supply systems were successfully implemented), however, and in adoption of chlorine powder to urban water supplies around the country, that the link between density and disease was broken (Melosi 2000). At that point, urban typhoid fever levels plunged dramatically. That is, the development of water supply and sanitation systems along with advances in germ theory and water treatment technologies helped cities in the country largely overcome traditional health burdens (Melosi 2000).
Overcoming health burdens allowed cities to further increase in density, which also created massive markets for products. Commercial districts separated from residential areas within cities and the beginnings of a mass market developed, particularly within the metropolitan areas of the country. Industrial production on a large scale developed within a national economy and with this came the beginnings of chemical pollution.
At about this time, another transition was occurring within cities of the developed world. Changes from horse and other animate powered modes of transportation to motor vehicles depended upon the development and the mass production of the technology, increases in average incomes, shifts in housing arrangements and the structure of cities, improvements in street paving, the rise in importance of engineers in city planning, the health impacts of horses and changes in the perceived use of streets, among other influences.
Interestingly, health advocates at that time promoted the automobile as an answer to horse pollution and hence as an environmental solution (McShane 1994).4
In this perspective, development proceeded through waves that followed linked changes in the economy. This relationship between these drivers and development patterns (whether contingently or structurally linked), created sequential shifts in many transitions (urbanization, demographic, health, nutrition, environmental, energy, etc.) in the Western experience. The long waves of economic growth (Kondratieff 1979) focused on economic and technical change, but included a number of other shifts over a 50-60-year period (Berry 1997). Work associating these shifts to patterns of historic growth in European and North American societies concluded that waves of development did exist, but too much emphasis was placed on the potential structural linkages with the economy (Maddison 1991).
We argue that the strength of the structural linkages is as important to current policy thinking as how conditions were addressed. Historically, in the USA addressing urban environmental issues took on a first-things-first) methodology (Warner 1955), which had (and continues to have) a strong (and inappropriate) presence in development thinking today. We argue that even if long waves of development did exist and were related to economic structural adjustments, they are very different if not absent today. Indeed, the emergence, timing and speed of environmental conditions have altered. These changes have been due to a shift in the drivers of the past, which together have changed time/space dynamics.
3.2.3 Time- and space-related effects and changes in the drivers of change
There has been a large body of literature that suggests the contemporary development context is significantly different from previous eras (see, for example, Held et al. 1999) . Importantly, globalization, defined by the stretching of a number of human relationships over space, is altering the way human activities and perceptions unfold. Globalization and domestic influences, over the past 30-40 years, have had particularly strong time- and space- related effects on the human-environment relation.
Time-related effects are changes in development patterns as a result of changing speed and efficiency of human socio-economic activities. Time-related effects draw places closer together and create urban dynamics across the globe forcing convergence among urban areas. That is, they create similar conditions across cities of different social, cultural and political histories and economic levels. Space-related effects concentrate increasingly diverse phenomena unevenly in spatial nodes (i.e. within and among cities) and create urban dynamics across the globe forcing divergence among urban areas. Space-related effects increase differences among cities, concentrating what was once unique across an
4 The horse, in the late nineteenth century city, rivalled humans in creating waste. In the USA, at the turn of the century, there were 3 million to 3.5 million horses in use. Engineers estimated that a city horse produced more than 20 pounds of manure and several gallons of urine daily, most of which ended up in the streets. Cumulative totals of manure produced by urban horses were staggering. For example, 26 000 horses used in Brooklyn and 12 500 horses in Milwaukee yielded about 200 and 133 tons of manure daily, respectively. In the mid-1880s, the discharges of 100 000 horses and mules, pulling 18 000 horse cars over 3500 miles of track nationwide, cluttered the nation's streets, corroded the metal streetcar tracks and also threatened the health of city dwellers. Moreover, since the life expectancy of a city horse was only about two years, carcasses were plentiful and difficult to move. New York City scavengers removed 15 000 dead horses in 1880. Often dead horses lay in the streets for days before they were carted away. It is not surprising therefore that the automobile was received as an environmental benefit (Melosi 2001; Tarr 1993).
entire nation, into its cities. Massey (1996), for example, has pointed out how different and diverse phenomena are increasingly concentrated in cities.
There is a significant history of studies of time/space effects. Within the literature, there are three interlinked ways of thinking about how these effects relate including: time/space convergence, time/space distanciation and time/space compression. Time/space convergence refers to the decrease in the friction of distance between places. It refers to the apparent convergence of settlements linked by transport technology. As transport evolved, travel time would be reduced between them, giving the sensation that they had moved closer together. The velocity at which settlements are moving together may be called the time/space convergence rate (Janelle 1968, 1969). This notion is often expressed as the 'world is an increasingly smaller place'.
Time/space distanciation refers to the stretching of social systems and relationships across space and time. The argument is that people interact in two ways: face to face, and remotely through transport and communications technologies. The first way of interaction occurs more often between people living in different nations, more frequently due to air travel. The second modality has become increasingly important with globalization, 'dis-tanciating' social relationships. Together, during the contemporary period, it is not necessary for people to be physically present at a particular location to be important social actors, as these relationships have been stretched over space (Giddens 1990).
Time/space compression refers to ' the annihilation of space through time' that lies at the core of the capitalist dynamic (Harvey 1989). While the concepts of time/space convergence and time/space distanciation do not offer an explanation for why social relations and development patterns have been stretched across space and subsequently dramatically changed the development context, time/space compression does. The argument is that this is one of the central processes of capitalist development. As 'time is money' the tendency for relations under this mode of production is to find ways to speed up the ' circuits of capital' so as to reduce the 'turnover time of capital' (i.e. the amount of time it takes to convert investment into a profit). As a result, technologies and policies to facilitate these processes facilitate time/space compression. The effect of time/space compression is disorienting and disruptive on both the balance of class power and social and cultural life.
This concept encompasses the descriptive accounts of time/space convergence and distanciation, making them a result of time/space compression. Ultimately the argument places an economic rationale at the core of change and not surprisingly this has been criticized by cultural scholars (Murray 2006).
To these three concepts of time- and space-related effects, we add a fourth, time/space telescoping. Time/space telescoping is also a descriptive narrative similar to t ime/space convergence and time/space distanciation. It is evident in the shifting patterns associated with development, such as environmental transitions, such that contemporary conditions and transitions occur sooner (at lower levels of income) change f aster (over time) and emerge more simultaneously (as sets of challenges) than had previously been experienced by the now developed world (Marcotullio 2005b' . Moreover, there are a number of different direct and indirect influences, including global economic, demographic and institutional shifts as well as local land use and policy influences that have helped to create these trends (Marcotullio 2005a), so it is theoretically different from time/space compression.
The notion of time/space telescoping stresses that the result of these changes in drivers is more than the speeding up development. China, for example, is not simply undergoing a quicker version of what the UK or the USA had experienced during the late nineteenth and early twentieth centuries. Rather, while speed is important, the addition of conditions and challenges appearing at lower levels of income and the layering of previous sequential development patterns, make the current context much more complex and bewildering.
Surprisingly, despite the diversity, complexity and rapidity of change, some of the conditions in the now developing world (i.e. those related to energy consumption) are more efficient or less environmentally harmful than those experienced by the developed world, as measured in a number of ways (i.e. supply and consumption of energy per capita).5 That is not to say that these conditions are good or good enough, but rather they are indeed significantly better than experienced in the past. Moreover, when examining the environmental impact of urban activities, at least in terms of energy consumption and related CO2 emissions, for many developing countries, the rapidly developing world is growing in a much less environmentally harmful manner. These are the notions that this study examines.
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