Cities and Greenhouse Gas Emissions: Moving Forward

Abstract

Cities are blamed for the majority of greenhouse gas (GHG) emissions. So too are more affluent, highly urbanised countries. If all production- and consumption-based emissions that result from lifestyle and purchasing habits are included, urban residents and their associated affluence likely account for more than 80 per cent of the world’s GHG emissions. Attribution of GHG emissions should be refined. Apportioning responsibility can be misguided, as recent literature demonstrates that residents of denser city centres can emit half the GHG emissions of their suburban neighbours. It also fails to capture the enormous disparities within and across cities as emissions are lowest for poor cities and particularly low for the urban poor. This article presents a detailed analysis of per capita GHG emissions for several large cities and a review of per capita emissions for 100 cities for which peer-reviewed studies are available. This highlights how average per capita GHG emissions for cities vary from more than 15 tonnes of carbon dioxide equivalent (tCO2e) (Sydney, Calgary, Stuttgart and several major US cities) to less than half a tonne (various cities in Nepal, India and Bangladesh). The article discusses where GHG emissions arise and where mitigation efforts may be most effective. It illustrates the need to obtain comparable estimates at city level and the importance of defining the scope of the analysis. Emissions for Toronto are presented at a neighbourhood level, city core level and metropolitan area level, and these are compared with provincial and national per capita totals. This shows that GHG emissions can vary noticeably for the same resident of a city or country, depending on whether these are production- or consumption-based values. The methodologies and results presented form important inputs for policy development across urban sectors. The article highlights the benefits and drawbacks of apportioning GHG emissions (and solid waste generation) per person. A strong correlation between high rates of GHG emissions and solid waste generation is presented. Policies that address both in concert may be more effective as they are both largely by-products of lifestyles.

Advancing urban metabolism studies through GIS data: Resource flows, open space networks, and vulnerable communities in Mexico City

“…The use of a UM approach to study Mexico City is still limited to a few research projects. Depending on the discipline and focus of the study, these vary with regard to the metabolic flows analyzed and scale of study (Delgado‐Ramos, 2013, 2015a, 2015b, 2021; Guibrunet et al., 2016; Hoornweg et al., 2011; Huerta‐Barrientos, 2018; Kennedy et al., 2015; Paez, 2010). However, the translation of these studies into spatially explicit accounts (e.g., GIS mapping) of resource flows/stocks and an understanding of the role of OSN in resource management in Mexico City are still limited to date.…”

“…Researchers have used UM frameworks to study the configuration of waste management systems, drinking water consumption, and water infrastructure (distribution system and sewer network) from an urban political ecology perspective (Delgado‐Ramos, 2015a; Guibrunet et al., 2016). Other studies have focused on the impact of material flows on GHG emissions (Delgado‐Ramos, 2015b; Hoornweg et al., 2011) and the assessment of a social–ecological metabolism (Huerta‐Barrientos, 2018), included Mexico City in a comparative study of 27 megacities worldwide (Kennedy et al., 2015), and examined the potential benefits of urban energy transition (Paez, 2010). Guibrunet et al.…”

Modeling Spatial Distribution of Carbon Sequestration, CO2 Absorption, and O2 Production in an Urban Area: Integrating Ground‐Based Data, Remote Sensing Technique, and GWR Model

“…Over half of the world's population is settled in urban areas, and this share is increasing over time, according, to the projections, by 2030, more than 60% of the world's population will live in urban areas, and by 2050, more than two thirds of the world will live in urban areas (Hoornweg et al., 2011; Kamal‐chaoui & Robert, 2009; Ritchie & Roser, 2018; Satterthwaite, 2008). The cities consume a great majority between 60% and 80% of energy production worldwide and account for a roughly equal share of global greenhouse gas emissions (Hoornweg et al., 2011; Kamal‐chaoui & Robert, 2009; Ritchie & Roser, 2018; Satterthwaite, 2008). Among greenhouse gases, carbon dioxide plays a critical role in global warming (Lal, 2004; Peters, 2001; Petit et al., 1999; Scott et al., 2002).…”

Synthesis of Urban CO2 Emission Estimates from Multiple Methods from the Indianapolis Flux Project (INFLUX)

“…City-wide emission estimates have traditionally been obtained using inventory-based methodologies, often adopted from the international Intergovernmental Panel on Climate Change (IPCC) approach and downscaled to the urban scale. 5,6 However, a review of traditional urban inventories reveals a mixture of methods and data sources making it difficult to compare cities or assess accuracy or consistency over time, 7−9 although efforts to standardize methodologies are underway. 10,11 Uncertainties in these city-scale emission estimates may be 50% to 100%, 12,13 insufficient to evaluate emission reduction policies.…”