Climate Change and Cities Second Assessment Report of the Urban Climate Change Research Network SUMMARY FOR CITY LEADERS ARC3.2 Figure 1: Components of the Second Assessment Report on Climate Change and Cities (ARC3.2) and their interactions. ARC3.2 Summary for City Leaders Urban Climate Change Research Network Second UCCRN Assessment Report on Climate Change and Cities Prepared for release at COP21 Climate Summit for Local Leaders in Paris, France (December 2015) © 2015 Urban Climate Change Research Network (UCCRN) Center for Climate Systems Research, Earth Institute, Columbia University Recommended citation: Rosenzweig C., W. Solecki, P. Romero-Lankao, S. Mehrotra, S. Dhakal, T. Bowman, and S. Ali Ibrahim. 2015. ARC3.2 Summary for City Leaders. Urban Climate Change Research Network. Columbia University. New York. Cover photo: Rio de Janeiro by Somayya Ali Ibrahim URBAN CLIMATE CHANGE RESEARCH NETWORK ARC3.2 SUMMARY FOR CITY LEADERS Tis is the Summary for City Leaders of the Urban Climate ways that increase risk to cities. Tis conclusion is based on many Change Research Network (UCCRN) Second Assessment Report diferent types of evidence, including the Earth’s climate history, on Climate Change and Cities (ARC3.2) (Figure 1). UCCRN is observations of changes in the recent historical climate record, dedicated to providing the information that city leaders—from emerging new patterns of climate extremes, and global climate government, the private sector, non-governmental organizations, models. Cities and their citizens already have begun to experi- and the community—need in order to assess current and future ence the efects of climate change. Understanding and anticipat- risks, make choices that enhance resilience to climate change ing these changes will help cities prepare for a more sustainable and climate extremes, and take actions to reduce greenhouse gas future. Tis means making cities more resilient to climate-relat- emissions. ed disasters and managing long-term climate risks in ways that protect people and encourage prosperity. It also means improving ARC3.2 presents a broad synthesis of the latest scientifc cities’ abilities to reduce greenhouse gas emissions. research on climate change and cities1. Mitigation and adap- tation climate actions of 100 cities are documented through- While projections for future climate change are most ofen out the 16 chapters, as well as online through the ARC3.2 Case defned globally, it is becoming increasingly important to assess Study Docking Station (www.uccrn.org/casestudies). Pathways how the changing climate will impact cities. Te risks are not to Urban Transformation, Major Findings, and Key Messages are the same everywhere. For example, sea level rise will afect the highlighted here in the ARC3.2 Summary for City Leaders. Tese massive zones of urbanization clustered along the world’s tidal sections lay out what cities need to do achieve their potential coastlines and most signifcantly those cities in places where the as leaders of climate change solutions. UCCRN Regional Hubs land is already subsiding. In response to the wide range of risks in Europe, Latin America, Africa, Australia and Asia will share facing cities and the role that cities play as home to more than half ARC3.2 fndings with local city leaders and researchers. of the world’s population, urban leaders are joining forces with multiple groups including city networks and climate scientists. Te ARC3.2 Summary for City Leaders synthesizes Major Tey are assessing conditions within their cities in order to take Findings and Key Messages on urban climate science, disasters science-based actions that increase resilience and reduce green- and risks, urban planning and design, mitigation and adaptation, house gas emissions, thus limiting the rate of climate change and equity and environmental justice, economics and fnance, the pri- the magnitude of its impacts. vate sector, urban ecosystems, urban coastal zones, public health, housing and informal settlements, energy, water, transportation, In September 2015, the United Nations endorsed the new solid waste, and governance. Tese were based on climate trends Sustainable Development Goal 11, which is to “Make cities and and future projections for 100 cities around the world. human settlements inclusive, safe, resilient and sustainable.” Tis new sustainability goal cannot be met without explicitly recog- nizing climate change as a key component. Likewise, efective Climate Change and Cities responses to climate change cannot proceed without understand- ing the larger context of sustainability. As ARC3.2 demonstrates, Te international climate science research community has con- actions take to reduce greenhouse gas emissions and increase cluded that human activities are changing the Earth’s climate in resilience can also enhance the quality of life and social equity. 1. Cities are defned here in the broad sense to be urban areas, including metropolitan and suburban regions. ARC3.2 CHAPTER 1. INTRODUCTION 1 ARC3.2 SUMMARY FOR CITY LEADERS Pathways to Urban Transformation Hyderabad, India Cairo, Egypt Paris, France Phnom Penh, Cambodia New York, USA Rio de Janeiro, Brazil As is now widely recognized, cities can be the main implement- design, and urban architecture. A portfolio of approaches is avail- ers of climate resiliency, adaptation, and mitigation. However, the able, including engineering solutions, ecosystem-based adapta- critical question that ARC3.2 addresses is under what circum- tion, policies, and social programs. Taking the local context of stances this advantage can be realized. Cities may not be able to each city into account is necessary in order to choose actions that address the challenges and fulfll their climate change leadership result in the greatest benefts. potential without transformation. Pathway 3: Risk assessments and climate action plans ARC3.2 synthesizes a large body of studies and city expe- co-generated with the full range of stakeholders and scientists riences and fnds that transformation is essential in order for are most efective. Processes that are inclusive, transparent, par- cities to excel in their role as climate-change leaders. As cities ticipatory, multi-sectoral, multi-jurisdictional, and interdisciplin- mitigate the causes of climate change and adapt to new climate ary are the most robust because they enhance relevance, fexibil- conditions, profound changes will be required in urban ener- ity, and legitimacy. gy, transportation, water use, land use, ecosystems, growth patterns, consumption, and lifestyles. New systems for urban Pathway 4: Needs of the most disadvantaged and vulnerable sustainability will need to emerge that encompass more cooper- citizens should be addressed in climate change planning and ative and integrated urban-rural, peri-urban, and metropolitan action. Te urban poor, the elderly, women, minority, recent immi- regional linkages. grants and otherwise marginal populations most ofen face the greatest risks due to climate change. Fostering greater equity and Five pathways to urban transformation emerge throughout justice within climate action increases a city’s capacity to respond ARC3.2. Tese pathways provide a foundational framework for to climate change and improves human wellbeing, social capital, the successful development and implementation of climate action. and related opportunities for sustainable social and economic Cities that are making progress in transformative climate change development. actions are following many or all of these pathways. Te pathways can guide the way for the hundreds of cities–large and small/low, Pathway 5: Advancing city creditworthiness, developing middle, and high income–throughout the world to play a signif- robust city institutions, and participating in city networks cant role in climate change action. Cities that do not follow these enable climate action. Access to both municipal and outside pathways may have greater difculty realizing their potential as fnancial resources is necessary in order to fund climate change centers for climate change solutions. Te pathways are: solutions. Sound urban climate governance requires longer plan- ning horizons, efective implementation mechanisms and coor- Pathway 1: Disaster risk reduction and climate change adap- dination. Connecting with national and international capaci- tation are the cornerstones of resilient cities. Integrating these ty-building networks helps to advance the strength and success of activities into urban development policies requires a new, sys- city-level climate planning and implementation. tems-oriented, multi-timescale approach to risk assessments and planning that accounts for emerging conditions within specifc, A fnal word on timing: Cities need to start immediately to more vulnerable communities and sectors, as well as across entire develop and implement climate action. Te world is entering into metropolitan areas. the greatest period of urbanization in human history, as well as a period of rapidly changing climate. Getting started now will help Pathway 2: Actions that reduce greenhouse gas emissions avoid locking-in counterproductive long-lived investments and while increasing resilience are a win-win. Integrating mitigation infrastructure systems, and ensure cities’ potential for the transfor- and adaptation deserves high priority in urban planning, urban mation necessary to lead on climate change. 2 ARC3.2 CHAPTER 1. INTRODUCTION URBAN CLIMATE CHANGE RESEARCH NETWORK Climate Observations and Projections