Section 2. Manufacturing and Construction (Batteries, Built Environment, Automotive, and other Industries)

Urban Carbon Management Strategies

Introduction

Urbanization is the shift in residence of the human population from rural to urban areas. It has been identified as one of the most important social transformations in the history of civilization (Ochoa et al., 2018), and has facilitated the emergence of societal benefits, such as improved economic access, the advent of public transportation, artistic expression, and other kinds of social innovations (Birch and Wachter, 2011; Guinard and Margier, 2018). Although urbanization has facilitated many social innovations, it has also led to adverse impacts to vital ecosystem services, including degradation of soil, air, and water quality (Ananda, 2018; Li et al., 2018). In this chapter, we explain how ecosystem impairment can be remediated following sustainable development—which is development that meets the needs of the present without compromising the ability of future generations to meet their own needs (Bnmdtland, 1987)—with a particular focus on carbon management strategies in urban ecosystems. Figure 1 shows the conceptual flow of this chapter. It is important to note that chapter references to ‘carbon’ or ‘carbon emissions' may encompass other greenhouse gas (GHG) emissions which is sometimes expressed in the form of a carbon dioxide equivalency.

Global and regional urbanization trends

The world population has reached nearly 7.6 billion (UN DESA, 2017; US CB, 2019). Of this population, about 55% live in urban areas. By year 2050, the world population is expected to be about 9.8 billion, with the percentage of people that are expected to live in urban areas projected to increase to 68% (UN DESA, 2017; UN DESA, 2018a). This means approximately 2.5 billion people could be added to urban areas within the next few decades (UN DESA, 2018a).

The conceptual flow of this chapter, where parenthesized numbers indicate the amount of strategies, tools and/or

Figure 1. The conceptual flow of this chapter, where parenthesized numbers indicate the amount of strategies, tools and/or

technologies.

Figure 2 shows population trends in the major regions of the world. North America has the greatest urbanized population. Much of this urbanization can be attributed to robust economic and public transportation developments in the United States (U.S.) over several decades (Auch et al., 2004; World Atlas, 2019).

Trends for all regions suggest that urbanization will continue through 2050, however, some European countries—such as Bulgaria, Croatia, Latvia. Lithuania, Poland, Moldova, Romania, Serbia, and Ukraine—are projected to experience population declines due to the persistence of low fertility rates

Percentage of urbanized population per world region. The historical and projection data displayed comes from

Figure 2. Percentage of urbanized population per world region. The historical and projection data displayed comes from

UN DESA (2018b).

(UN DESA, 2017). Asia and Africa are expected to have sizeable increases in their urbanized populations through 2050 despite having relatively low current urbanization percentages. For Asia, an increasing urbanized population is projected despite Japan’s ageing population challenges (Tamiya et al., 2011; UN DESA, 2018a). Year 2050 projections suggest that much of the world’s urbanized population will be concentrated in the countries India and China of the Asian region and Nigeria of the African region (UN DESA, 2018a).

Carbon Effects of Urbanization

Urban classification

There are universal classifications for least developed and more developed countries. The intensity and types of emission effects vary based on the urbanization class. Least developed countries (LDCs) are defined as lower-income countries that have low levels of human assets (e.g., insufficient access to and/or ineffective health, nutrition and educational programming), are vulnerable to economic and environmental shocks, and have structural impediments to sustainable development (UN EAPD, 2019). The United Nations recognizes 47 LDCs: 33 in Africa, nine in Asia, four in Oceania, and one in Latin America and the Caribbean (UN CTAD, 2017). The North American and European regions have no identified LDCs. The remaining 148 countries of the world are classified as more developed countries (MDCs), which are higher-income countries with relatively high human assets that are capable of withstanding economic and environmental shocks. Urbanized areas can be further distinguished based on economic and population factors (UN WESP, 2014; UN SD, 2017). Urban classification is limited to LDC and MDC for the purposes of linking general carbon management strategies.

Carbon effects of MDCs

MDCs show trends of intensifying carbon effects. Developing countries or nations that fall into the MDC class tend to have high growth rates of carbon emission. Emission growth rates are found to be highest in places that have fast growing economies (Raupach et al., 2007). China and India have been two of the fastest growing economies in the world (Alam et al., 2016; Hewko, 2017). In comparison, developed countries, like the U.S., tend to have lower growth rates of carbon emissions over the last decade but more cumulative emissions over several decades (Hoesly et al.. 2018; US EPA, 2017). Therefore, China, India, and the U.S. are used as exemplars of MDC carbon patterns.

Developing nations, such as China and India, har e experienced rapid growth in carbon emissions and urbanization. China has the most carbon emissions of any country in the world (US EPA, 2017). These high emission rates can be attributed to energy-intensive industries and associated economic activities (Wang and Zhao. 2015). India, which is the thud largest carbon emitting country in the world (US EPA, 2017), shares many of the same emission characteristics.

As a developed nation, the U.S. currently has lower carbon emission and urbanization growth rates than China yet is the second largest carbon emitter in the world (US EPA, 2017). The U.S. also has the highest cumulative emissions of any country in the world due to early economic development, which has resulted in the longest period of relatively high annual carbon emission rates, and the U.S. has had a disproportionately high carbon emission total over the last several decades, in comparison to China and India (Hoesly et al., 2018: Quere et al., 2016). Other developed MDCs, like those in Europe, also have relatively high carbon emission rates, urbanized population percentages, and per-capita emission rates. The U.S., however, remains the leader in cumulative carbon emissions and per-capita emission rates to date.

Carbon effects of LDCs

There are some common factors that tend to drive carbon effects in LDCs. One of the major factors is country-level attempts to attain economic stability. However, economic stability for LDCs tends to be linked to increased energy consumption. For instance, the causal links between carbon emissions and economic growth in Bangladesh, which is one of the nine LDCs in Asia, show that further economic growth is uni-directioually linked to increased energy consumption (Alam et al., 2012). This suggests that economic growth in Bangladesh also means growing energy use. Lower-income countries that are in an economic growth phase are much more likely to use traditional energy sources, such as coal, that emit high concentrations of carbon (Steckel et al., 2015). Taken together, this suggests that LDCs that are actively progressing towards economic stability are contributing to global carbon emissions in systemic ways. It has, therefore, been suggested that countries like these use renewable, clean energy technologies to pror ide the energy support needed for their continued economic growth (Kaygusuz, 2012). Facilitating economic growth using renewable and clean energy technologies, however, comes with unique political and economic challenges (Ito, 2017).

Other major carbon effects

Carbon effects associated with tree cover and soil are introduced and descriptions are applicable to urban areas in both MDCs and LDCs.

2.1.3.1 Soil organic carbon (SOC) effects

The soil can release carbon into the atmosphere. Soil organic matter (SOM) is the organic component of soil that includes plant residue, carbon, decomposing organic matter, and stable organic matter (Bot and Beuites, 2005). SOC is vital to sustainable soil fertility (Wang et al., 2016). However, increased SOM decomposition from a wanning climate could release increased carbon emissions, considering SOM contains almost three times as much carbon as the atmosphere (Cheng et al., 2017; Knorr et al., 2005).

2.1.3.2 Urban tree carbon effects

Urbanization activities, including deforestation and land-use changes, can impact carbon concentrations in the atmosphere. Trees sequester carbon through the stomata duiing photosynthesis by storing carbon as a biomass. Stomata are pores of plant leaves, stems, and other organs that facilitate gas exchange and are vital to the photosynthesis process (Lai and Augustin, 2012). For instance, U.S. estimates show that urban trees store carbon at a rate of 7.69 kilograms of carbon per square meter of tree cover annually (Nowak et al., 2013). Street and park trees have been shown to benefit urban areas through carbon sequestration and shading effects while also providing other benefits, such as improved air quality and stormwater runoff reductions (McPherson et al., 2005; Nowak et al., 2006). The removal of urban trees for land use changes—such as the removal of a forested, urban park to build an apartment complex—not only allows carbon that could have otherwise been sequestered to enter the atmosphere, it also facilitates further carbon emissions, since trees can emit stored SOC after tree death.

Carbon Management Strategies and Tools

Urban carbon management strategies and tools are expansil e and have mutually-exclusive and synergistic qualities (i.e., they can be used singularly or combined to develop hybrid approaches that fit the needs and environmental profile of a given area). Major strategies and tools are described in this section.

Strategies

Five major strategies are highlighted for urban carbon management: (1) decentralized plant growth, (2) densification, (3) public transportation, (4) renewable energy and efficiency, and (5) urban agriculture.

 
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