Vulnerability Assessment
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CITY OF SOMERVILLE Climate Change Vulnerability Assessment JUNE 2017 January 2017 Commission on Energy Use and Climate Change Oliver Sellers-Garcia, Ex-officio Julie Wood Eliza Johnston Juliette Rooney-Varga Joshua Hodge Stephen Moore Vulnerability Assessment Advisory Committee Juliette Rooney-Varga Ramon Bueno Joshua Hodge Vanessa Boukili Philip Groth Municipal Liaisons Oliver Sellers-Garcia, Director, Office of Sustainability and Environment Hannah Payne, Sustainability Coordinator, Office of Sustainability and Environment Attributions The document was developed in coordination with: The City of Somerville Mayor’s Office The City of Somerville Office of Sustainability and Environment The City of Somerville Office of Strategic Planning and Development Metropolitan Area Planning Council (MAPC) Trust for Public Land (TPL) The document was prepared by: Arup Woods Hole Group Industrial Economics, Inc. Dr. Patrick Kinney, Columbia University Dr. Joyce Rosenthal, Columbia University MWH Global, Inc. (now part of Stantec) Cover Image Source: Eric Kilby. 2014. “Prospect HIll Tower - Towards Boston.” Licensed under CC BY-SA 2.0. https://www.flickr.com/photos/ekilby/14379261625/ Table of Contents i Letter from the Mayor ii Executive Summary 1 Section 1: Overview 4 Section 2: Regional Coordination 8 Section 3: Methodology 13 Section 4: Climate Exposure 24 Section 5: Vulnerability & Risk Assessment 58 Section 6: Priority Focus Areas 68 Appendices Image Source: Eric Kilby. 2014. “PowderHouse Circle Into Somerville.” Licensed under CC BY-SA 2.0. https://www.flickr.com/photos/ekilby/14431802234/in/photostream/ Letter from the Mayor The scientific evidence and consensus is clear: climate change is a reality that we cannot ignore. Just as each of us as individuals must do our part to reduce the carbon emissions that cause climate change, cities too must take action. Cities and towns must not only work to reduce local emissions, we bear the responsibility to protect our communities from the changes that are already underway. All cities around the world will experience some impacts of the changing climate. Hotter weather, sea level rise, and more intense rain and winter storms are just a few of the challenges we will likely confront. With this Climate Change Vulnerability Assessment, we now have a better understanding of what threats Somerville may specifically face in the coming years, better positioning us to make smart decisions now. This study shows that in Somerville we are fortunate to be less exposed to the threats of sea level rise than some of our neighbors, and we have pinpointed the specific places where we know we are more exposed and action must be taken. For one, stronger, more frequent rain presents a risk of flooding in areas where we work, live, and commute. We are already taking action to reduce this threat with ambitious infrastructure projects in Union Square. We recognize that, with the information in this study, we have an opportunity to make decisions in the coming years that can reduce our risks both within Somerville and in the Boston region. Keeping Somerville a safe, prosperous, inclusive community is a complex challenge, and climate change is just one fact that will affect our success. But over time it may well prove to be the most significant factor. In Somerville though, we have proven over and over again—from fighting for the Green Line Extension to continually improving the quality of our schools to clearing ten feet of snow—that we, as a community, are up for the difficult challenges. Determination is in ample supply here and it will serve us well as we problem solve around climate change. Coupled with our Greenhouse Gas Inventory, which was released last year, this study will also serve us well. It provides the baseline for Somerville’s climate change planning so we know where to start and where we need to go. With this report in hand, I look forward to continue working with our community to develop the right strategies to address climate change locally and to advance our goals to make Somerville carbon neutral and resilient. Joseph A. Curtatone Mayor Somerville Climate Change Vulnerability Assessment i Executive Summary Somerville’s Climate Action Efforts The Somerville community has a long-standing and passionate interest in addressing climate change. In recent years, the City of Somerville has taken a leadership role in understanding the impacts of climate change, highlighted by Mayor Joseph A. Curtatone’s commitment to achieving carbon neutrality by 2050 and the city’s launch of the SustainaVille initiative to assist Somerville in the implementation of practical solutions to achieve carbon neutrality and resilience. Somerville is also a committed leader on a regional and global scale with its membership in the Global Covenant of Mayors for Climate & Energy1, a global coalition of city leaders committed to combatting climate change and reducing greenhouse gas (GHG) emissions, and its involvement in the climate change preparedness efforts of the Metro Mayors Coalition2, a coalition of 14 Boston-area municipalities working to develop regional solutions to advance climate action. The Climate Change Vulnerability Assessment (CCVA) is the next step towards advancing the city’s commitment to climate action and creating a comprehensive climate change plan for the City. The CCVA and Somerville’s Greenhouse Gas Inventory establish the baseline understanding of Somerville’s contribution to climate change and anticipated impacts from climate change. Together, these studies will serve as the baseline for developing the analysis and strategies that will comprise the City’s Climate Change Plan. Figure 1: Somerville Climate Change Planning Process CCVA Overview The general trends in Somerville associated with the world’s shifting climate include warmer temperatures, more extreme precipitation events, and sea level rise. In many ways climate change will intensify impacts that Somerville is already experiencing, such as precipitation-based flooding and heat waves. However, climate change will also present new impacts from sea level rise and storm surge along the Mystic River. Somerville is already working to reduce some of these known risks through planning 1 Global Covenant of Mayors for Climate & Energy, 2016. https://www.compactofmayors.org/ globalcovenantofmayors/. 2 Metro Mayors Coalition: Climate Preparedness Commitment, 2015. http://www.mapc.org/ climate-preparedness. ii Somerville Climate Change Vulnerability Assessment and infrastructure decisions. For example, the City is carrying out a $40 million project - with a $13 million grant from the Commonwealth of Massachusetts - to support sewer and water infrastructure upgrades in Union Square in order to alleviate strains on the existing and outdated stormwater infrastructure. In order to improve decision making as Somerville prepares for climate change, the analysis in this study identifies key priorities that Somerville will need to address in order to enhance resilience to intensified and new impacts caused by climate change. High emissions (RCP 8.5): Climate change will impact all cities and towns in some way. Eastern Massachusetts emissions continue to rise is particularly vulnerable to sea level rise and storm surge and New England will have to adapt to a hotter and wetter climate. In Somerville, sea level rise and storm surge, throughout the 21st century and increased precipitation, and heat are all concerns. However, Somerville’s flood risks expected temperatures increase are somewhat unique. Unlike some neighboring coastal communities, precipitation will between 4.7 and 8.6°F by 2100. affect larger portions of Somerville than coastal flooding. Coastal flooding will primarily occur through two known pathways located on Somerville’s borders, as opposed to a widely exposed coastline. Somerville has the opportunity to drastically reduce coastal Low emissions (RCP 4.5): flood vulnerability by finding solutions to prevent flooding at these two pathways. Similar emissions peak around 2040 to most communities in the Greater Boston region, heat will significantly increase in the and then decline and expected summers, intensifying existing public health issues associated with heat waves and temperatures increase between causing new public health concerns due to shifts in vector borne diseases. 2.0 and 4.7°F by 2100. The priorities identified in this assessment will be carried through into the next phase of Somerville’s climate change planning process. The Climate Change Plan will identify strategies and actions to address these priorities and to collaborate regionally with state actors and neighboring communities to collectively increase resilience to climate change. CCVA Methodology This study assesses the City of Somerville’s vulnerability to the following climate factors: sea level rise (SLR) and storm surge; precipitation; and, temperature. The scope of this assessment is limited to the direct impacts of these climate stressors within Somerville’s borders and does not extend to secondary impacts from climate factors or more regional and global climate considerations, such as food insecurity and population migration as a result of climate change. The vulnerability assessment was organized around a three step process, based on the widely-used methodology developed by ICLEI – Local Governments for Sustainability.3 Step 1: Establishing a climate baseline for the various types of climate exposures. Step 2: Understanding the vulnerabilities and assessing the overall