Blacktop to green grounds

Citizen engagement and the un-paving, permeabilizing, and cultivating of routine public spaces

Prepared 14 April 2008 for Prof. Shauna Brail (INI306Y1Y, University of Toronto).

————— —— —————

In this paper:
Executive summary
Introduction
Literature review
Urban comparisons
Description and discussion
Paths of possibility: recommendations
Endnotes
Conclusion
Appendices
    Appendix A
    Appendix B
    Appendix C
    Appendix D
    Appendix E
    Appendix F
    Appendix G
    Appendix H


Executive summary

As we collectively understand the extent of how much we and our predecessors have altered the morphology and meteorology of this planet, we are increasingly more concerned with how we might be able to undo some of our impact. We forgo plastic bags for reusable bags. We rely more on waste diversion using green bins. For those able to, we compost in and for our back yard. And perhaps here and there, more attention is being given to bicycling as a mode choice, just as buying locally has become a familiar refrain.

Underneath this, there’s also a sense that maybe, just maybe, we’re not doing enough. Some of the most neglected places — ones ripe for ecological restoration (note that this doesn’t equate to natural, which is a contestable concept subject to a myriad of interpretations) — are literally right under our feet. The city, regardless of the season, hints at it, too: in winter, it’s where snow is piled high; it’s where detritus collects after spring thaw and autumn’s falling; in summer, it’s the nether zones between sidewalk (actually being used) and scorching street — a sidewalk extension as hot as the street, but less likely to be shaded the way the main strip might. These areas also help polluted rainwater redirect quickly to street drainage, placing stress on an already-ancient sewer system.

By introducing a symbiosis between excessive summer heat found in the city (the urban heat island), and heat-storing concrete and asphalt, why couldn’t these spaces function just as well if they had plants instead? Why are we more interested in green roofs and less so with green grounds?

This report is not necessarily a call-to-action, but it gives Evergreen another way to optimize its knowledge capital in both ecological restoration and community involvement in a new way — a way that invites individual as well as community participation in the most ordinary public spaces.


Introduction

Imagine walking barefoot through a nearby park on a hot summer day. Each footstep over grass feels refreshingly mild, especially wherever trees provide shade. But the next step onto a sunny, treeless sidewalk feels like venturing onto a frying pan. That’s because it is: on the sunniest, hottest days, concrete and asphalt can reach 70°C — hot enough to cook eggs (Hasebe, et al. 2006, 697; Milesi 2004, 8). Impervious surfaces like this store heat energy and — in addition to an atmospheric inversion layer created by air pollutants from combusted fossil fuels — trap solar radiation near the surface like a blanket (Ahrens 1988, 512; Appendix A). Likewise, dark rooftops with low albedo (reflectivity) absorb radiation, increasing the hydro required to cool building interiors.

There are two separate, but very interrelated challenges here.

First, the extent to which impervious surfaces like concrete and asphalt exist affects how much heat energy is absorbed for release both before and after sundown: a small-town urban heat island, or UHI, is lower than in a city like Toronto, which is covered by thousands of square metres of impervious surface area coverage, or ISAC — such as roadways and parking lots — and surrounded by other Greater Golden Horseshoe communities that co-contribute to create a massive, unified UHI footprint (Appendix B). Foliage is a natural air conditioner because it uses solar energy to evaporate moisture, cooling the air around it. Anthropogenic, or human-generated, pollution and water vapour emissions — such as from car exhaust or coal hydro plants — contribute to heating in urban areas, particularly during summertime (Montávez et al. 2008, 238). Second, impervious surfaces aggravate drainage, limiting indigenous ecosystems from absorbing precipitation into watersheds, resulting in exceptional flash flood events and increased pollution runoff (Appendices C, D, & E).

Evergreen advances a mandate of ecological restoration within urban areas by bridging community-based participation between citizens, private concerns, and public land managers (Lindsay 2008, prologue). This multi-pronged approach — educating students, community outreach groups, and homeowners — enables citizens with a better understanding of how our urban presence and daily activities alter our living environment. Each stewardship planting event Evergreen facilitates teaches citizens to identify native and invasive species; how local watersheds are integral to our ecosystems; and how the value of preserving and restoring green space is both an ecological concern as much as it is a liveability one. But this largely focusses on public parks and greenways, schoolyards and, in Vancouver, consulting home owners on native species. Public-owned and semi-public spacing beyond these areas receive less attention.

Toronto features many undistinguished easements, medians, walkways, and underutilized lots that in some way have ISAC. Not only are they aesthetically unattractive, but they also disable pathways to “bring nature into the city”. They contribute to these two problems, concentrating storm water runoff and funnelling street and yard pollutants into watersheds. This works against the city’s ecological health, and it detracts from spaces which could be brought under community stewardship.

Increasingly, active citizens are exploring guerrilla gardening as a way to reduce ISAC by assuming self-driven stewardship over public space. This tack is relatively new, but these results are sowing stronger community ties and cultivating a greater sense of local citizenship. With the City of Toronto already allocating funding initiatives to reduce its UHI, Evergreen’s experience enables it to reach out to these citizens, create new partnerships, and set the tone for ad hoc public gardening. Even badly neglected, impervious urban strips can, through citizen participation, actively curtail the city’s UHI effect by returning plants to the most pedestrian of places. And leave your eggs at home.


Literature review

Alexandri, Eleftheria & Jones, Phil. 2008. Temperature decreases in an urban canyon due to green walls and green roofs in diverse climates. Building and Environment, 43: 480–93.
The authors start by finding that UHIs cannot be remedied alone by designating park spaces within an urban space. While parks can lower temperatures in a localized context (e.g., within the park), the presence of buildings and pavement are chiefly responsible for solar radiation retention. They examine the application of green roofs and green walls on building construction and envelope retrofits to create “green canyons”; assessing whether this method inversely impacts UHI conditions; and whether various climatic regions benefit from this approach. Using quantitative analysis and calculations based on three different canyon deployment scenarios, peak summer months in Montréal, Riyadh, Mumbai, London, Beijing, Brasilia, Hong Kong, Athens, and Moscow are factored to assess which method works most efficiently, and to what extent each reduces heat retention. The results indicated surface (ground-level) reductions of ~4°C (Moscow, London) to ~8–12°C (Hong Kong, Mumbai, Riyadh); and at one metre above green rooftops (paired with green walls) reduction yields of ~15°C (Moscow, London) to ~25°C (Hong Kong, Mumbai, Riyadh, Beijing, and Athens) indicate that the adding foliage atop (or instead of) ISACs — more so the narrower those “canyon” walls are, like side streets — point to not so much a solution to cover all buildings (which may not happen for years, if ever), but that eliminating ISAC with flora in urban ecosystems effectively reduces air temperatures and a need for hydro-intensive cooling methods.

Kim, R., Lee, S., Lee, J., & Gee, C.S. 2007. Thermal properties of water-absorbing and surface modified porous pavements. Materials Science Forum, (544–5): 913–6.
The authors in this comparative study examined thermal properties of porous versus conventional, high-density pavements in relation to finding ways to curtail UHI effects. Study results revealed two situations which suggest that only in one circumstance — when pavement is wet (e.g., following a rain shower) — does porous pavement actually exhibit lower thermal properties. When it dries, it returns to a temperature comparable to high-density pavement. This is notable in the context of continuing discussions in Toronto relating to using porous pavement alternatives on pay parking lots: curtailing UHI is not likely to be significant outside of precipitation events.

Piracha, Awais L. & Marcotullio, Peter J. (Eds.). 2003. Urban ecosystem analysis: identifying tools and methods. Tokyo: United Nations University Institute of Advanced Studies.
The authors identify key themes relevant to urban concentration by taking a broad scoped view of global urban systems. They recognize a need to examine urban areas as a “natural environment” of its own, particularly when accounting for natural spaces within the urban area (e.g., parks, undeveloped features, etc.), but also allowing for the study of how living things (animals, plants, etc.) interact with urban ecosystems. They distinguish this approach from the Chicago School, which only addresses social/spatial relations. The city-as-human-ecosystem lens enables planners, environmentalists, and even economists a “holistic view of the city as a consumer and digester of resources and a creator of waste products.” From this examination of both socio-ecomonic and bio-physical considerations, they explain that an “urban ecosystems analysis” approach can better understand the relations between human and non-human environmental activity in urban and peri-urban areas. They establish that developed areas do alter local climates (e.g., UHIs, light pollution, etc.); that water and flood management alters freshwater and marine ecosystems; and that dwellings made by humans can concentrate the discharge of pollutants due to impermeable surfaces. They also denote that built-up areas are not entirely impervious, and cities actually have plenty of capacity to support more permeable green space.

Poon, Chi-Sun. 2007. The use of aggregate in concrete in Hong Kong. Conservation and Recycling, 50(3): 293–305.
As part of larger municipal-regional efforts to reduce ground impermeability and limit UHIs, a new way to manage C&D — construction and demolition — aggregates (old concrete, tile and clay bricks) is needed for environmental management. Poon investigates Hong Kong as a case study on how that city-region is finding new ways to re-purpose C&D aggregate. As a function of its limited development space, Hong Kong relied on landfill projects for disposing C&D aggregates. In recent years, public awareness of marine ecosystems has curtailed how much landfill is being redirected to create “new land”. Recycling and repurposing C&D aggregate is now being explored: finer grades for mixed use in the pouring of new building foundations, while coarser grades for layer foundations in road construction. Poon quantitatively compares different grades of C&D aggregates to test their effectiveness against conventional aggregate sources, finding that in projects where concrete is used for structural integrity, it is not recommended to use both fine and coarse C&D aggregates; it is, however, suitable to combine one variety of C&D aggregate with the other being new, or “naturally” sourced. Alternately, recycled aggregates can be used in non-structural applications like street curbs. In Toronto’s context, there are limits to dumping C&D aggregate at places like the Leslie Street Spit, but by removing ISAC for the creation of urban garden space, C&D slabs may be reusable for pouring new building foundations (like MEC Toronto) and repairing existing street structures.

Quayle, Moura & van der Lieck, Tilo C.D. 1997. Growing community: a case for hybrid landscapes. Landscape and Urban Planning, 39: 99–107.
Quayle and van der Lieck investigate community within familiar spaces like public parks and front yards. These places, they posit, invite interaction and social networking. Memory and history, especially in older areas of a city, resolve further dimension of one’s invested stakes on locality. But underlying challenges of utilizing less-defined space by and for community (citizens, neighbours, etc.) for sake of involvement and interaction, raises a new proposal called the hybrid landscape. Citizens already use ephemeral spaces, such as a spot on the beach. The hybrid function of such a space illustrates how ownership is continually re-negotiated, but under a communal agreement of actively maintaining that space over time — even when no one is using it. Hybrid landscaping is proposed by the authors for spaces like the creation of narrow municipal greenways. These are public spaces and not owned by any one individual. Hybrid landscapes operate on three rules: 1) control of these spaces is gradually transferred from municipalities to community, paced by the latter; 2) an openness to interpretative use of that transferred space by community; and 3) advancing the prior two rules in small steps without framing a master-plan mentality, allowing for continual refinement and mutual agreement of how that space is enjoyably reclaimed. In Toronto, areas where ground-level ISACs — which invite their own destructiveness through social and functional neglect — can be removed and gradually reclaimed by local community, strengthening social linkages and cultivating a vitality immediately apparent to anyone passing through or joining that community.


Urban comparisons

  • Vancouver’s easement gardening. Citizens in Vancouver are mobilizing to plant seeds (and cultivate previously-seeded areas) on publicly-owned parcels of land. Easements, medians, and abandoned lots are typical candidate spaces the citizen-gardeners select on a strictly ad hoc basis. Because this horticulture is not sanctioned by the city — though it has not enforced a vested interest to challenge the activity — this type of do-it-yourself mobilization is referred to as guerrilla gardening. In one case study, an abandoned lot adjacent to an industrial park was chosen by local residents and named Cottonwood Gardens. Over the span of a decade, the lot went from being barren to lush (Appendix F). Another guerrilla gardening group employed “seed balls” to “sow” onto areas where ISAC removal was either not practical, possible, or permitted. These seed balls dissolved in the rain, passing the seeds through seams to germinate in soil underneath. Within months, these medians teemed with a myriad of wildflower species, and required no upkeep beyond the depositing of seed balls (Appendix G). By contrast, the Toronto Public Spacing Committee informally participates in guerrilla gardening, though not demonstrably to the extent seen in Vancouver.
  • Chicago’s “Green City in a Garden”. Mayor Richard Daley has advanced an assertive greening effort throughout Chicago, both in terms of planting a higher ratio of trees-to-local citizens and in green roof development. On this front, Chicago far outpaces Toronto: in a North American survey from 2005 based on green roof surface area coverage, Chicago ranks first, whereas the top Canadian city was Ottawa, ranked tenth (Morello 2006, ¶5). While the City of Toronto is calling for increased green roof coverage, particularly in core UHI areas, this only concerns one segment of a manifold challenge. Green roofs, along with green walls and, more to the point, replacing ISAC at ground level with flora comprise a holistic, turnkey approach to lowering UHI. Any one without the others prevents substantial, ground-level cooling.
  • London’s litter-busting, defensible garden space. As an example of citizen-level stewardship over publicly-owned (but not publicly-maintained) land, a resident started a garden under his own volition after tiring of an adjacent lot being a magnet for littering. In response, he gardened at night to establish a boundary of public and private space; the police, curious to see what was afoot, left him alone (McClish 2007, 116). Blomley (2004, 621) argues that the role of community ownership over untended public rights-of-way (e.g., empowerment by gardening on such spaces) removes the “unassigned . . . no man’s land” of unclaimed space — leading to neglect, public safety challenges, and loss of connection with one’s immediate surroundings. He also reconciled a connection between Newman’s notion of “defensible space” and Jacobs’ “eyes on the street”, that these divergent concepts can coexist (ibid. 616, 634). By comparison, such gardening techniques have historically been frowned on in Toronto — but usually in larger untended spaces, not tiny easements (McClish 2007, 116).


Description and discussion

This capacity for concrete, asphalt, and tar to store and release captured solar energy over time contributes to the UHI effect (Ahrens 1988, 512). UHIs occur whenever a concentration of these surfaces — typically impervious, such as concrete or asphalt — capture, retain and delay the release of infrared solar radiation, en masse, heating air near the surface and preventing the crepuscular cycle of evening cooling from proceeding in earnest (Fick & Harris, 2002, 36).
UHIs are linked to several environmental circumstances that contribute to an urban ecosystem’s effect on the environment:

  • Hotspots. Heat retention by ISAC generates warmer micro-climates within a city — sometimes by as much as 4°C over rural areas, and 3°C at midnight (Wong & Jusuf 2008, 166). This alters floral and faunal habitation in these micro-climates. False-colour imaging can distinguish UHIs and help pinpoint a region’s hotspots (Appendix B).
  • Water runoff. Torrential cloudbursts can dump enormous volumes of water onto terrain very suddenly. In Toronto, such an event occurred on August 19, 2005, when a flash flood on Black Creek washed away part of Finch Avenue (City of Toronto 2007, 25; Appendix C). While porous ground and foliage are better able to absorb and dissipate water more gradually into watersheds, ISAC and conventional storm water management averts water runoff absorption by funnelling deluges into storm drainage systems; triggers creeks and rivers to spill out of banks with greater frequency; and forces rain to rapidly collect into drainage systems, taxing municipal infrastructure (Appendix D).
  • Dumping pollutants. Storm water drainage from paved surfaces collects whatever pollutants have accumulated since the last rainfall. This runoff spills into watersheds as heterogeneous plumes (Appendix E), forcing closure of beaches in Toronto as pollutants and bacteria spill into the Lake ecosystem (City of Toronto 2007, 27).
  • Increased consumption. While temperatures are higher within the UHI, hydro consumption also climbs as a function of increased air conditioner usage. In turn, air conditioning units concentrate and exhaust heat into the atmosphere, further hampering an urban ecosystem from dissipating solar heat collected by ISAC. As well, motorized vehicles use more fuel when running air conditioners, adding to inversion layer pollution.
  • Power grid strain. Hydro infrastructure on hot days is also taxed, increasing air pollution around regions where hydro facilities use combustive means to generate power (e.g., coal, natural gas, etc.). In exceptional cases on some of the hottest days, hydro grids are susceptible to being pushed beyond failure due to overload. If this for whatever reason occurs, it can trigger a chain reaction of power outages, similar to the August 14, 2003, blackout that plunged much of the eastern U.S. and Ontario into darkness.

Because this report challenges the UHI effect in large part because of ISAC prevalence and its unintended role of storing and releasing tremendous amount of heat energy in areas that don’t need it, it is worth advancing permeablizing strategies for places where removing ISAC is impractical or impossible, such as a roadway or the main part of a sidewalk. For instance, a green berm hosting the growth of indigenous plants offers no less a functional barrier than a conventional concrete median.

One proposal of reducing UHIs is worth reviewing: Hasebe, et al. (2006, 697) propose a new technology called Road Thermal Energy Conversion, or RTEC, which is designed to capture heat energy through circulating water pipes embedded underneath ISAC arterials, such as a road or sidewalk. This water, sourced from a nearby lake or river, is pumped into the RTEC system using a small pump; exiting hot water flows out into the original water source through a passive thermoelectric generator which, theoretically, could supply the hydro input necessary for the intake pump, thus creating an independent power system (ibid., 698–9).

A similar technology called the Road Energy System, proposed by a Dutch concern, employs the same network of water pipes, but instead of constant inflow/outflow to a natural water source, it is instead sequestered to a deep artificial reservoir where, during the winter, it is pumped back to the surface to warm ISAC roadways for cleaner de-icing — doing so with less road salt or sand (Max 2007, B4). Because this water maintains a relatively constant temperature in this reservoir, the previous winter’s water flow can also be used to cool pavement slightly for the following summer.

An obvious drawback to both these proposals comes from the exorbitant expense of creating the piping infrastructure underneath ISAC paths, requiring the tearing apart those surfaces. Further, the RTEC process of constant water flow bears heavy resemblance to Toronto’s Deep Lake Water Cooling system; in both, questions remain unanswered as to whether this outflow of warmed water at the lake bottom interrupts the semi-annual cycle of water circulation within the lake, and necessary to replenish oxygen (Boyce, et al. 1993, 615). Such a cycle interruption, Boyce argues, may lead to anoxia at the lake bottom, resulting in a biotic collapse affecting fauna and flora near the surface.

These new technologies are discussed to illustrate and underscore the strictly reductive approach of macro-managing UHI issues and their inherent limitations. Cost impracticalities, engineering challenges, and an ongoing environmental–economic dialectic, compel this report to advocate for holistic, small-scale, and community-originated approaches to UHI curtailment. This ground-up approach is within Evergreen’s domain of experience, lending itself well to potentially confronting the challenges of reducing UHI and subtracting ISAC on publicly-owned spaces within the city.


Paths of possibility: recommendations

  • Facilitate grant support for hybrid landscaping & “guerrilla gardening”. While the de-centralized nature of citizen-driven, ad hoc gardening groups may not lend to heavy organizing the way a park stewardship planting event might, offering them access to the raw planting materials (which can add up very quickly) encourages more citizen participation: if the materials are ready to go (e.g., seeds, saplings, seed balls), it means less obstacles to on-the-spot planting events. As McClish (2007, 115) notes, “Guerrilla gardening can be an individual endeavor or a collective project, and doesn’t involve invading corporate chains, or being an inspired prankster.” Evergreen’s added stake in this joint effort comes in the knowledge base of ensuring that only indigenous species are cultivated, and educating guerrilla gardeners on the characteristics of invasive plants.
  • Advocate recycling of discarded aggregates, particularly those slabs removed for gardening in easement and publicly-owned areas. This is an opportunity to divert the volume of C&D aggregates to Leslie Street Spit and to invite conservation groups like Friends of the Spit to co-host both stewardship planting events on the Spit and, in return, use their support to facilitate ISAC-reducing gardening. A portion of C&D aggregates can continue to expand the Spit while reducing the air pollution of hauling it across town.
  • Advocate change for municipal approaches to by-law enforcement. Though a sticking point in the past, use this as an opportunity to establish linkages between municipal storm sewer infrastructure strain and an imperative to allow citizens to remove ISAC and take up citizen-level gardening in their locality. As noted in Toronto’s Wet Weather Flow Master Plan (2007, 7), the City’s expressed interest to reduce strain wherever possible, would benefit from this approach, and it can stave off the timing of capital infrastructure projects while enabling the City to function as an agent of fostering communities to work more closely together on increasing the amount of hybrid landscaping (and proportionate reductions of ISAC).
  • Match grant funding for ISAC-heavy neighbourhoods. Bridge together stewardship planting opportunities for ISAC-heavy neighbourhoods with at-risk groups who live in those neighbourhoods — where ISAC is especially acute and defensible space is scant. These planting events would be exceptional in that jackhammers might be needed to remove ISAC to prepare for planting. Further pinpoint which neighbourhoods lack citizen ownership over nearby publicly-owned space and make these a first priority in a three-tier stewardship system, the first being redirection (which is proportionately allocated the highest ratio of grant funding for planting supplies); then categorize two lower levels of priority and fund at decrementing grant levels: revitalization (for gentrifying neighbourhoods), and protection (for wealthy neighbourhoods). The criteria for prioritization is the assessing extent of publicly-owned, but unused ISAC spaces which would be ideal candidates for hybrid landscaping and guerrilla gardening.
  • Operate as an urban ecological restoration hub for networking & education. Facilitate alliances between ad hoc public space groups like the Toronto Public Spacing Committee with at-risk youth and other underrepresented groups who are willing to learn how to garden in the city and to show how self-driven gardening builds stronger community ties and a stronger sense of urban citizenship through a sense of ownership in the most familiar areas: one’s own neighbourhood.


Conclusion

As the bigger picture of tomorrow looms, we worry about how healthy our habitats will be as the global climate is swayed faster and faster by our collective contributions to its changes. The romanticizing of relying on large-scale projects to solve big problems seems, simplistically speaking, a common sense one: bigger battles big; bigger wins. But this reduces the options for possible smaller-scale solutions (if not remedies) to the most daunting plans. Big often fails (or just doesn’t know) to adjust for changes in the small details, which then undermines its efficacy.

Some grand schemes to address human-caused heat issues, such as the urban heat island effect, are theoretically feasible and abstractly demonstrable, but what they frequently lack is the means to be tried — given such high risk for complications, reliance on a centralized approach, and the high expenses in creating the first prototype. Instead, our focus should scale down to the micro level, looking at the challenges as an interrelated gestalt, not as separate options. After all, green roofs need green streets to work at their best. A more holistic approach is what Evergreen already enables in its Common Grounds, Learning Grounds, Home Grounds, and Evergreen Brickworks initiatives.

Nevertheless, these are foundational, and still highly structured programmes which could be scaled down to even smaller levels — smaller than current stewardship events. In a way, what this report presents is a new initiative that would thrive somewhere between Home Grounds and Common Grounds in its mandate, but would optimally work best on its own. As this relates to hybrid landscaping, removing impervious slabs, and working at small, non-master-planned levels to build relationships with neighbours, these Street Grounds would show a way to engage citizenship and urban participation at the most familiar and mutually common level: the neighbourhood.


REFERENCES

Ahrens, C. Donald. 1988. Meteorology today: an introduction to weather, climate, and the environment, 3rd. ed. St. Paul: West Publishing Company.

Alexandri, Eleftheria & Jones, Phil. 2008. Temperature decreases in an urban canyon due to green walls and green roofs in diverse climates. Building and Environment, 43: 480–93.

Blomley, Nicholas. 2004. Un-real estate: proprietary space and public gardening. Antipode, 35(4): 614–41.

Boyce, F.M., Hamblin, P.F., Harvey, L.D., Schertzer, W.M., & McCrimmon, R.C. 1993. Response of the thermal structure of Lake Ontario to deep cooling water withdrawals and to global warming. Journal of Great Lakes Research, 19(3): 603–16.

City of Toronto. 2007. City of Toronto municipal code. Toronto: City of Toronto.

City of Toronto. 2007. Wet weather flow master plan: implementation report 2006. Toronto: City of Toronto.

Fick, Steven & Harris, Eric. 2002. Simmer in the city: heat-seeking images reveal urban hot spots. Canadian Geographic, 122(4): 36.

Hasebe, M., Kamikawa, Y., & Meiarashi, S. 2006. Thermoelectric generators using solar thermal energy in heated road pavement. IEEE 2006 International Conference on Thermoelectrics, 697–700.

Kim, R., Lee, S., Lee, J., & Gee, C.S. 2007. Thermal properties of water-absorbing and surface modified porous pavements. Materials Science Forum, (544–5): 913–6.

Lindsay, Lois. 2008. Growing opportunities: a social service agency’s guide to garden programming. Toronto: Evergreen.

Max, Arthur. 2007. Hot pavement tapped for heat among solar-power innovations: Dutch engineering firm siphons reusable energy from roads, parking lots. Toronto Star, 29 December: p. B4. Toronto: Toronto Star Newspapers Ltd.

McClish, Carmen. 2007. Social protest, freedom, and play as rebellion (Doctoral dissertation, University of Massachusetts Amherst, May 2007). UMI, 3275782.

Milesi, Cristina. 2004. Monitoring and modeling human interaction with ecosystems (Doctoral dissertation, University of Montana, 2004). UMI, 3126546.

Montávez, J.P., González-Rouco, J.F., & Valero, F. 2008. A simple model for estimating the maximum heat intensity of nocturnal urban heat island. International Journal of Climatology, 28: 235–42.

Morello, Lauren. 2006. High energy prices spur green roofing boom. World Business Council for Sustainable Development. Geneva and Washington: World Business Council for Sustainable Development. Retrieved 31 March 2008.

Piracha, Awais L. & Marcotullio, Peter J. 2003. Urban ecosystem analysis: identifying tools and methods. Tokyo: United Nations University Institute of Advanced Studies.

Poon, Chi-Sun. 2007. The use of aggregate in concrete in Hong Kong. Conservation and Recycling, 50(3): 293–305.

Quayle, Moura & van der Lieck, Tilo C.D. 1997. Growing community: a case for hybrid landscapes. Landscape and Urban Planning, 39: 99–107.

Wong, Nyuk Hien & Jusuf, Steve Kardinal. 2008. GIS-based greenery evaluation on campus master plan. Landscape and Urban Planning, 84: 166–82.


Appendix A


Temperature inversion layer demonstrating the acceleration of the UHI effect. Photo: Astrid Idlewild.


Appendix B


Greater Golden Horseshoe urbanization. ISAC (the UHI footprint) in pink. Courtesy European Space Agency.


Appendix C


19 August 2005: Black Creek washout of Finch Ave. Courtesy Spacing.ca.


Appendix D


Storm sewer geyser during flash flood event. Courtesy WRRC, University of Hawaii.


Appendix E


Humber River plume after storm, showing polluted runoff. Courtesy City of Toronto.


Appendix F


Cottonwood Gardens, Vancouver. Clockwise from top-left: empty lot, mid 1991; first year, late 1991; added pond, 1994; self-sustained growth, 1998. Note the same black locust tree at left. Courtesy Oliver K, flickr.com.


Appendix G


7th & Hemlock, facing north, Vancouver [left] just after guerrilla gardeners placed seed balls along public median; same location [right], three months later. Courtesy Urbanwild, flickr.com.


Appendix H


Clockwise from top-left: jackhammering reclaimed lot, Tucson; thruway guerrilla garden, Seattle; curbside wildflowers; new guerrilla garden, Toronto; curbside flowers, Ontario; curbside garden, New Orleans.

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