Managing climate change risks in cities: a study of mitigation and adaptation strategies

Abstract

Climate change is an extreme case of externality. Its global nature has prompted analysis at higher geographical scales like country, region or global levels. However the origin of most emissions and impacts of climate change are locale specific. Urban human settlements are major contributors to greenhouse gas emissions and are also likely hot spots for risks from future climate change impacts. In developing countries, where major urbanization is expected in the current century, need and scope exist for integrating climate change and urban development strategies to avoid irreversible lock-ins. This research addresses the following questions: 1. What would be the likely impacts of climate change on built environment, energy use and access to water in urban areas? 2. What emissions scenario would emerge if current urban development policies continue? 3. To what extent can sustainable urban development policies, considering climate perspective, enhance adaptive and mitigative capacity for climate change? 4. How would climate change impact the investment patterns in urban areas? What would be the opportunities and threats for urban development due to the changed pattern? An integrated modeling framework has been developed to address these questions. The framework includes integrating regional climate models for urban policy, Monte Carlo simulation for investment pattern shift assessment, Asia-Pacific Integrated Model Energy Snapshot tool (ESS) for urban GHG mitigation analysis, marginal cost assessment for water sector, and geographic information system (GIS) analysis for flooding. Six case studies were conducted for the cities of Delhi and Mumbai to cover the whole spectrum of risks posed by climate change as well as to study the effectiveness of sustainable urban development policies in reducing greenhouse gas emissions. However, the conclusions drawn hold relevance across all the cities. The analysis established that climate change would pose a serious threat to the future urbanization unless properly managed. The study found that in case of Delhi the climate change threats would be in the form of increased riverine flood frequencies of up to 1.5 व 2 times for floods of lower intensity and 2.2 व 4 times for floods of higher intensities over 2000-2050; higher frequency of local flooding in low lying areas by 3 times; water scarcity of the order of 600 million gallons a day amounting to monetary losses of INR 16 billion per annum; an increase in marginal cost of water by 2 times as well as intensified urban heat islands due to shift in annual temperatures by 5.25 degree Celsius and related increase in energy consumption over 2000-2100. The study also found that the real estate sector in low lying areas of Mumbai can absorb a decline in prices of not beyond 15%, while, under climate change, the declines can be expected to be higher. The study further established that urban policies related to energy, water, air quality, and land-use provide significant opportunities for gaining multiple dividends vis-व-vis sustainable development and climate change adaptation objectives. It is also clear that urban sustainable development policies are effective in achieving substantial mitigation of GHG emissions across all urban sectors and indicate that, if implemented, across major urban settlements, could play an important role in achieving Indiaवs commitments to a climate friendly development. The key contributions of the study lie in integration of Regional Climate Models, River CAD, Glacial Models and Urban Policy in a GIS framework, tangible assessment of risk exposure of cities to different climate change related phenomenon, water resource and marginal cost assessment under climate change in urban context, setting up AIM ESS for Delhi, implications of climate change on investment, evolving set of policy actions required to enhance the adaptive and mitigative capacity in urban areas, assessment of effectiveness of sustainable urban development policies in achieving emission reductions and development of policy road map. These would be of interest to policymakers, city planners, business and insurance market developers, global and national researchers.