Quantifying the environmental impacts due to resource consumption in cities

Abstract

In the past few decades, we have witnessed unprecedented impacts of climate change. The increase in Green house gas emissions due to human activities has disastrous implications for earth including an increase in global mean temperatures, rise in sea level and melting of polar ice caps. Climate change has
impacted all forms of human life on earth and if unchecked, poses a threat to human existence. With more than 50% of global population currently living in the cities and the upward trend of people migrating to the cities expected to increase in the next few decades, cities are one of the major contributors to climate change. Nearly 80% of global energy and 75% of global resources are consumed in cities. Thus, there is an urgent need to tackle the environmental impacts of cities.
In this research, we develop a methodology to quantify and analyze the environmental impacts of cities by considering the consumption of all resources
occurring in a city. The methodology is applied to the city of the Hague in the Netherlands but can be replicated for other cities as well. The research is divided into the following components: Firstly, a small literature review is conducted to identify different elements in a urban system. The literature review also assesses different models used to quantify environmental impacts of a city . Out
of the three models reviewed in the study, Life Cycle Assessment (LCA) is found to be the best fit for assessing environmental impacts of city. Knowledge gaps surrounding the applicability of LCA to a city are identified and based on the knowledge gap, research question is framed. Following the literature
review, a top down approach is used to identify products or activities by residents of a city that have an environmental impact. Following that, a data disaggregation methodology is developed to downscale data related to resource consumption and activities from the national or European level to local level of
neighbourhoods in a city. The disaggregated data is then quantified using LCA and analyzed for different geographical regions, different resource use categories and different demographic groups in a city. Finally, based on the environmental impacts, commonly implemented policies in cities around the world to reduce GHG emissions are modelled and analyzed for the case study : The Hague. This is followed by detailed discussion on results, limitations, conclusions and directions for further research. The main conclusions that can be drawn from the research are that resource use categories in which
intervention by cities is possilble account for nearly 70% of Global warming potential (GWP): 45% mobility, 15% waste,10% energy. Larger households have a higher impact due to mobility whereas smaller households have higher impact due to energy. Environmental impacts are further analyzed for clusters of
neighbourhoods based on their socioeconomic indicators. Finally, the policy interventions analyzed show a potential to reduce net GWP by 25% in the Hague