Cities as nuclei of sustainability?

Rybski, Diego; Reusser, Dominik E.; Winz, Anna-Lena; Fichtner, Christina; Sterzel, Till; Kropp, Jürgen P.

doi:10.1177/0265813516638340

Cited by 46 publications

(49 citation statements)

References 52 publications

(100 reference statements)

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“…That is, emissions of these pollutants show an 'economy of scale/parsimony with scale', where 'scale' is measured by the settlement population and both emissions and population are aggregated within contiguous developed land use areas (see SI). This is broadly in line with previous results for CO 2 emissions for cities in developed countries [33]. For SO 2 , the sublinear relationship was statistically weaker (r 2 <0.6) (see section 2, and SI table S1, for details).…”

Section: Resultssupporting

confidence: 91%

Urban form strongly mediates the allometric scaling of airshed pollution concentrations

MacKenzie

Whyatt

Barnes

et al. 2019

Environ. Res. Lett.

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We present allometric-scaling relationships between non-point-source emissions of air pollutants and settlement population, using 3030 urban settlements in Great Britain (home to ca. 80% of the population of that region). Sub-linear scalings (slope<1.0; standard error on slope ∼0.01; r 2 >0.6) were found for the oxides of nitrogen (NO x ) and microscopic airborne particles (PM 10 and PM 2.5 ). That is, emissions of these pollutants from larger cities are lower per capita than would be expected when compared to the same population dispersed in smaller settlements. The scalings of traffic-related emissions are disaggregated into a component due to under-use of roads in small settlements and a fraction due to congestion in large settlements. We use these scalings of emissions, along with a scaling related to urban form, to explain quantitatively how and why urban airshed-average air pollutant concentrations also scale with population. Our predicted concentration scaling with population is strongly sub-linear, with a slope about half that of the emissions scaling, consistent with satellite measurements of NO 2 columns over large cities across Europe. We demonstrate that the urban form of a particular settlement can result in the airshed-average air pollution of that settlement being much larger or smaller than expected. We extend our analysis to predict that the likelihood of occurrence of local air pollution hotspots will scale super-linearly with population, a testable hypothesis that awaits suitable data. Our analysis suggests that coordinated management of emissions and urban form would strongly reduce the likelihood of local pollutant hotspots occurring whilst also ameliorating the urban heat island effect under climate change.

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Section: Resultssupporting

confidence: 91%

Urban form strongly mediates the allometric scaling of airshed pollution concentrations

MacKenzie

Whyatt

Barnes

et al. 2019

Environ. Res. Lett.

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“…This uncertainty is reinforced by other studies reporting either linear [91] or superlinear [92] values of the exponent governing the scaling of the total CO 2 . Furthermore, depends on additional factors and in particular decreases with the GDP per capita of the country a city belongs to [93]. In addition, a recent study of French cities suggested a parabolic behavior of CO 2 emissions versus population, implying the existence of a threshold above which a larger population leads to smaller emissions [94].…”

Section: Co 2 Emitted By Cars In Citiesmentioning

confidence: 99%

The statistical physics of cities

Barthélemy

2019

Nat Rev Phys

103

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Challenges due to the rapid urbanization of the world -especially in emerging countriesrange from an increasing dependence on energy, to air pollution, socio-spatial inequalities, environmental and sustainability issues. Modelling the structure and evolution of cities is therefore critical because policy makers need robust theories and new paradigms for mitigating these problems. Fortunately, the increased data available about urban systems opens the possibility of constructing a quantitative 'science of cities' with the aim of identifying and modelling essential phenomena. Statistical physics plays a major role in this effort by bringing tools and concepts able to bridge theory and empirical results. This Perspective illustrates this point by focusing on fundamental objects in cities: the distribution of urban population, segregation phenomena and spin like models, the polycentric transition of the activity organization, energy considerations about mobility and models inspired by gravity and radiation concepts, CO 2 emitted by transport, and finally scaling that describes how various socio-economical and infrastructures evolve when cities grow.

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“…Este tipo de métricas como instrumento de comparación espacial, de optimización de simulaciones urbanas y de cambios de usos son de gran importancia para entender la estructura y composición de los paisajes simulados (Aguilera, 2010). 2011352,97 1993-2011-35 2030116,88 2011-2030-202 205081,31 2011-2050-334 Compacidad promedio GYRATE_MN 2011218,07 1993-2011-3 2030208,28 2011-2030-5 2050170,17 2011-2050 Forma promedio SHAPE_MN 256,52 2011-2030-251 2050718,84 2011-2050-513 Distancia promedio ENN_MN 2011282,19 1993-2011-35 2030441,59 2011-203036 2050396,18 2011-2050 Por otra parte, respecto al escalamiento urbano se puede indicar que el comportamiento sublineal de las emisiones CO 2 en el sistema de ciudades chileno se asocia a una economía de escala (Cottineau, Hatna, Arcaute y Batty, 2017), tal como sucede en las grandes ciudades de los países desarrollados como Estados Unidos, Alemania, Italia, Singapur, Bélgica, Finlandia, Japón, Francia, Suecia, Reino Unido, Holanda, Canadá, Australia, Suiza o Noruega (Rybski et al, 2016). Esto sugiere que mientras en los países en desarrollo las ciudades pequeñas son más eficientes en la emisión de CO 2 , en los países desarrollados es el caso de las grandes metrópolis (Rybski et al, 2016).…”

Section: Discussionunclassified

“…La tendencia identificada se podría estimar como un rasgo positivo para la sostenibilidad urbana, en términos de volúmenes brutos emitidos (>4,3 millones de toneladas/año en el caso de Santiago), sin embargo es necesario mencionar que las relaciones de escalamiento dependen fuertemente de la definición de los límites de las ciudades (Arcaute et al, 2014;Louf & Barthelemy, 2014). Las unidades funcionales o morfológicas pueden influir en los exponentes resultantes, por lo que no se puede excluir un sesgo si los países en desarrollo utilizan sistemáticamente definiciones diferentes (Rybski et al, 2016). Esta diferencia también se puede aplicar por las distintas definiciones de lo urbano que realizan las instituciones públicas en Chile, por ejemplo, MINVU, INE, Municipios.…”

Section: Discussionunclassified

Dispersión y Escalamiento Urbano en el Sistema de Ciudades Chileno

et al. 2017

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ResumenLa expansión espacial incesante de las ciudades, el aumento de la segregación socio-espacial y el aumento del nivel de emisiones afectan severamente al medio ambiente y conforman estructuras emergentes e insustentables. El enfoque de los sistemas complejos, la ecología urbana y la ecología del paisaje nos ayudan comprender algunas de las propiedades de este crecimiento urbano. Para ello, se estudia la dispersión del paisaje urbano de 43 ciudades y conglomerados urbanos chilenos, entre 1993, 2003 y 2011, utilizando distintas métricas del paisaje urbano: fragmentación, elongación y aislamiento, en base a coberturas del Observatorio Urbano (MINVU) y al procesamiento en el programa Fragstat. También, se realiza un escalamiento del tamaño de las ciudades según el nivel de emisiones de CO 2 de manera exploratoria. Los resultados muestran que Santiago presenta los mayores porcentajes de fragmentación y el máximo crecimiento, junto con las ciudades Arica y Calama; la mayor parte experimentan procesos de elongación (Los Ángeles, Chillán e Iquique) y gran parte aumentan su aislamiento (Illapel, San Antonio y Copiapó). Por su parte, el escalamiento de las emisiones presenta un comportamiento sublineal (0,8). Los datos exhiben una alometría heterogénea que dependen estrechamente de la calidad de los datos utilizados, transitando de un modelo de ciudad relativamente compacto a uno difuso y disperso. Los métodos de simulación espacial de la dispersión y de escalamiento pueden servir como proxy para evaluar la sustentabilidad urbana, en la medida que ayudan a determinar la tendencia global de urbanización y pronosticar cómo evolucionarían los sistemas urbanos.Palabras clave: Sustentabilidad urbana, dispersión urbana, sistemas complejos, Fragstat. AbstractIncessant spatial expansion of cities, the increasing socio-spatial segregation, and rising levels of emissions severely affect the underlying environment and generate emerging and unsustainable structures. The approach of complex systems, urban ecology and landscape ecology helps us to understand some of the properties of this urban growth. In order to do this, the urban landscape fragmentation of 43 Chilean urban systems were calculated, between 1993, 2003 and 2011, using landscape metrics: fragmentation, elongation and isolation. Spatial layers of the Urban Observatory (MINVU) were processed in Fragstat program. Also, a scaling of the cities according to the level of CO 2 emissions is carried out in an exploratory way. The results show that Santiago presents the highest percentages of fragmentation and maximum growth, along with the cities Arica and Calama; most of the cities undergo elongation processes and most of them increase their isolation (Illapel, San Antonio and Copiapó). On the other hand, the scaling of the emissions presents sublineal pace (0,8). The data show a heterogeneous allometry that depends very closely on the quality of the data used, moving from a model city relatively compact to a diffuse and disperse one. The spatial simulation methods of urba...

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Cities as nuclei of sustainability?

Cited by 46 publications

References 52 publications

Urban form strongly mediates the allometric scaling of airshed pollution concentrations

Urban form strongly mediates the allometric scaling of airshed pollution concentrations

The statistical physics of cities

Dispersión y Escalamiento Urbano en el Sistema de Ciudades Chileno

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