New Orleans in the wake of Hurricane Katrina. Photo by Jocelyn Augustino for FEMA.
“In wretched outcomes, the devil is in the details.”
— Jane Jacobs
Arguably no problem facing the human species today is more daunting — and at the same time, more pressing — than the reduction of greenhouse gas emissions to mitigate the increasingly grave threat of climate change. While the science is still unclear about the range of alternative pathways to mitigation and adaptation, there is now an unequivocal consensus within atmospheric science and related disciplines that the phenomenon is occurring, and that it is already beginning to bring — and without remedy is likely to bring with increasing severity — a series of human catastrophes.
Yet it is also surely true that greenhouse gas emissions are only one aspect of an even wider human problem of unsustainable resource depletion and degradation. Both topics raise deeper issues still about the ability of humans to respond effectively in the face of inherently uncertain scientific knowledge about critical future events, and the often-associated (and increasingly problematic) consequences of political controversy and inaction.
It is encouraging to observe, however, that we humans have acted effectively on occasion to manage just such future events, under just such conditions. Perhaps the most relevant example is the so-called Montreal Protocol in 1987, an international treaty to control emissions of substances that deplete the planet’s critical ozone layer. The treaty, together with a series of follow-on actions, has been widely hailed as a positive example of global environmental management (UNEP, 2014).
However, when it comes to the reduction of emissions of greenhouse gases (hereafter termed GHGs) the problem appears much more daunting. First, it is evident that there are many more economic and political disincentives against taking strong action, shared by many more interests — notably including developing countries, who often see such action as a serious threat to their own pressing economic and human development goals.
More deeply, there is a high degree of uncertainty arising from the sheer complexity of the systems that shape consumption and emissions — most notably, the urban systems in which we move, consume, waste, and otherwise generate most of the ultimate demand for resources and emissions. It is safe to say that the dynamics of these systems — that is, the systems that comprise cities, suburbs and towns, together with their hinterlands — are among the most complex of any we know. They include myriad variables, many of them obscure, together with their myriad interactions. The situation is even more complex because urban systems are affected by perhaps the most notoriously difficult variables of all, those of human behavior.
Yet precisely because urban systems act as concentrated sources of GHG emissions, they present an especially attractive target for management. The wide variations in per-capita emissions between cities with different forms — for example, the high GHG emissions associated with sprawling suburban forms, relative to more compact urban forms — does suggest this is an important area for investigation and development.
Furthermore, precisely because urban systems are complex, progress in understanding their dynamics in the formation of GHG emissions may well produce other insights about the dynamics of urban systems and related phenomena, with potential applications beyond the specific problem of GHG emissions mitigation. In this sense, the problem of urban dynamics and GHG emissions may well be a kind of “lens” issue, whose examination may help to bring into focus other so far intractable challenges in our time.
My own involvement in research on urban form and greenhouse gas emissions (the subject of my doctoral dissertation completed in 2015) was motivated by my own recognition of a significant lacuna in the research on emissions from urban systems. In 2009 I was invited to participate in the IARU Scientific Conference on Climate Change in Copenhagen, a lead-up to the unsuccessful climate treaty negotiations of that year. I was asked (by a colleague and session organizer who was a member of the Intergovernmental Panel on Climate Change) to present some survey research on the role of urban form that I had previously conducted. My recognition of the immature status of the research at the conference, and the failure of the subsequent treaty negotiations, convinced me that important research work remained to be done to support and to inform policy and practice in the future. Only with a more solid evidence-based foundation could we make progress in an otherwise lethargic world of policy and practice.
Specifically, I found that there is a relatively mature body of research on building systems, their emissions sources, and potentially effective strategies for management. At another, larger scale, there is also a relatively mature body of research on the emissions generated by transportation systems, notably automobiles and other vehicles. These two components do account for a significant percentage of urban-generated emissions, and indeed all emissions generated from consumption activities — perhaps as much as half, depending on the methodology used to measure emissions generation.
However, I found that an important part of the picture is incomplete. It was readily apparent that these two components do not cover the full set of urban factors that affect emissions, and there is a range of significant if smaller urban factors between them that are much less well understood. They include infrastructure systems (including streets) and their patterns of scale and connectivity, infrastructure operating energies and transmission losses, patterns of sun and wind, patterns of distribution of uses and activities, and patterns of consumption, among others — in short, the many factors that constitute and are shaped by urban form beyond the individual building scale, but short of the scale of transportation systems per se. Crucially, this intermediate zone also connects building systems to the systems of transportation, and helps to explain how they are interrelated through urban form. Thus, it is a key part of a complete picture of the role of urban form.
The urban factors in this intermediate zone — the factors of urban morphology — are also the factors that were of such interest to Jane Jacobs and Christopher Alexander throughout their careers. It soon became apparent to me that a contribution of research to address this lacuna could be useful to my own work, and to the further investigation of their ideas.
There was a second crucial piece of that agenda. I recognized that to be useful in practice, my research project must do more than identify a set of findings, which were likely to remain abstract. It must provide tools to actually guide design in practice — or at least, provide the basis for them, allowing further development and improvement by others — in the form of decision support and scenario-modelling tools. I will not describe here the prototypical “scenario-modeling” tool that I developed — it is beyond the scope of this book, and covered in another book — other than to say that one can readily see the influence of both Christopher Alexander and Jane Jacobs in the result. I can also add that this is just an early version of the kind of tool that is needed, and as I concluded, more work on this and other tools is urgently needed.
This topic is particularly urgent because, as my earlier research suggested, alternative models of practice and supporting policy could achieve significant emissions reductions from current baselines. By contrast, “business as usual” development models are likely to result in dramatic increases of rates of emissions. This is because these inefficient models are now guiding development in many emerging economies around the world — a condition that is likely to further accelerate dangerous levels of emissions in the decades ahead.
Yet as noted previously, progress in reversing these trends has been stymied by geopolitical problems, inherent scientific uncertainties, and incentives against action — as the 2009 Copenhagen treaty negotiations demonstrated. In North America, which has become a model emulated by other regions, there is relatively poor comprehensive guidance for policy and design, and a low level of action in response. Project methodologies abound (for example, ratings systems like LEED-ND) but, as I discussed in my dissertation, they have been criticized for their lack of basis in evidence
This means that there is an urgent need for concrete advancements in effective mitigation science, translated into effective practice and policy. Specifically, there is a need for effective modelling of the dynamics of emissions from urban form, and the results of specific urban design and policy choices available. Only then can actions be tied to outcomes, including new incentives and new drivers of effective changes to policy and practice. This research must be inter-disciplinary in nature, combining climate science, urban morphology, urban design, behavioral economics, software engineering technology and other disciplines. That was the broad context of my own specific research, and the research framework on which it was developed.
While I was deeply concerned by what I learned initially about the magnitude of the problem, I was also equally impressed by preliminary evidence I found for the magnitude of the potential opportunity. My initial research showed a striking correlation between urban form and rates of emissions per capita in cities around the world — correlations that were not readily accounted for by other evident factors, such as climate, demographics, cultural norms or other expected variables. Of course, correlation is not cause, and the work remained to tease out the factors and show how they are causative, as part of a coherent explanatory model.
Figure IV.4.1. Comparison of country (gray) and city (red) GHG emissions per capita. Data is from 2005-2007 national inventories gathered under UNFCC standards. Source: World Bank (2011)
The initial evidence I found played a major role in motivating, and later formulating, my core research hypothesis. Figure IV.4.1 is a typical example. It shows a striking divergence in emissions per capita between five cities and the countries in which those cities are located (using data from national inventories in 2007-2009). The emissions for those countries as a whole include other cities, of course, as well as suburban and rural populations. As can be readily seen, there is a major delta — on the order of 200% to 300% — between dense, mixed, multi-modal cities like New York, London, Tokyo, Stockholm and Barcelona, and the United States, the UK, Japan, Sweden and Spain as a whole.
The comparison between countries is even more revealing. For example, the per-capita emissions for the United States as a whole are on the order of 300% higher than those of Sweden. This delta cannot easily be explained away by obvious factors such as economic prosperity, since Sweden has a higher per-capita income than the USA. Nor is climate an obvious factor, since Sweden’s winter climate is harsher on average. There are indeed other factors that might account for some of the delta, such as contributions of non-emitting energy sources and the like. But it became apparent to me that none of these factors could readily account for the magnitude of the delta. The one consistent variable was a great divergence of urban form, from dense, mixed, multi-modal cities to much lower density, dispersed, mode-dependent settlements.
Perhaps the most sobering delta of all was that between the USA as a whole and the city of Stockholm — an astonishing 600% increase in per-capita emissions. I pondered the meaning of this divergence. Was the average citizen of the USA six times more prosperous, healthy or happy in their life choices? There was certainly no available evidence to suggest that. Or, as seemed much more likely, were US citizens simply squandering over 80% of their GHG-emitting energy resources, without receiving any real benefits? Was part of this profligate waste coming from the influence of urban forms? If so, how could this be documented, and what could be done to reverse it — particularly in view of the rapid urbanization now taking place in many parts of the world?
I drew three key conclusions from this research. First, the effect of urban form on greenhouse gas emissions is far higher than currently acknowledged. Especially important, sprawling, disordered, and especially car-dependent places, offering “drive-through” lifestyles, have very high rates of per-capita emissions in comparison to more compact, walkable, transit-served places.
Second, the baseline of “business as usual” development continues to generate high-emissions forms of urbanism around the world. The implications for continued increases in greenhouse gas emissions, and increasingly catastrophic effects of climate change, are profound. They call for urgent global action, as a matter of priority.
Figure IV.4.2. Typical car-dependent development around new McDonald’s sites, built in the last ten years, in (clockwise from upper left) China, India, Romania and Brazil. In spite of the UN’s “New Urban Agenda” and similar reforms, this high-resource consumption pattern is still “business as usual” for urban development around the world today. Images: Flickr.
Third, the issues of greenhouse gas emissions are inseparable from those of resource depletion, ecological impacts, and environmental contamination (including pollution and invasive species). All of them are inseparably linked to the kinds of cities and towns we build. When we build more integrated, compact, mixed-use cities with healthy public space systems, of just the kind called for in the New Urban Agenda, all of these joined-up problems are mitigated. When we build sprawling, disordered, high-consumption cities, with disordered or diminished public space systems, all of these problems are exacerbated.
It seems we have a fundamental choice. We cannot leave these problems to fix themselves — they surely will not — but neither can we treat them in isolation from one another, and from the larger “kind of problem a city is.” To do so would be to play “Whack-a-Mole” with our problems, and to see the proliferation of more unintended consequences. We can only treat cities, and the other matters under our care, as “joined-up problems,” requiring joined-up responses.
This is indeed what Jacobs and Alexander urged us to do.