Planning for Climate Readiness — And Growth

This is an expanded version of the article that appeared in the print version of Planning magazine.

By Lawrence Susskind, Anna Doty, and Adam Hasz

In the last decade, unprecedented storm events — from Superstorm Sandy to hurricanes Harvey, Irma, and Maria — have sent a clear message to coastal cities across the nation: We must do more to anticipate and manage severe flooding and other climate-related disruptions.

Some cities have already begun this work by mapping their vulnerabilities and looking for ways to enhance their resilience. New York, San Francisco, and Boston are among some of the cities considering changes in land-use regulation, investments in conservation, and infrastructure modifications aimed at protecting high-value coastal areas and the people who live and work in them. Philanthropic initiatives such as the Rockefeller Foundation's 100 Resilient Cities have helped in this regard.

Few cities, however, have used the results of the rich data and information contained in their vulnerability assessments to revise their master plans. Some have enumerated broad goals for "climate readiness," but they have not spelled out specific steps for implementation.

By any measure, too many people are unprotected from potential flood risks and increasing heat levels, as cities continue to promote new development in flood-prone — but highly desirable — areas as their economic growth strategy. The tension between unchecked urban growth and climate-smart development is very real.

Boston and its neighbor, Cambridge, are taking seriously the need to connect the results of their climate vulnerability assessments with emerging master planning efforts — while also considering development needs — even if they still have many steps ahead in this uphill climb.

The authors of this article, all affiliated with the Department of Urban Studies and Planning at MIT, zeroed in on two neighborhoods — South Boston and the Alewife District of Cambridge — to better understand why development continues to be given priority in areas with high climate vulnerabilities. Both places face severe flooding risk.

Through our research, we learned how economic development needs are driving decisions with regard to resilience. Given the scarcity of land in Cambridge and Boston, construction moratoria seem very unlikely, even in the most vulnerable areas. Planners for each neighborhood have used data-driven tools to identify compelling strategies for increasing resiliency, but this will only be possible if tax revenue from new development can be captured. And it is unclear whether these actions will be enough. In the strongest zoning changes proposed, new buildings would be required to be resilient to the impacts of a one-percent-chance flood. Both cities face legal challenges to any new zoning, and even the toughest proposals would be inadequate to protect from floods after 2070.

Our conclusion: Market forces won't drive the changes needed to produce lasting resiliency. Only master planning that's truly long-range — 50 years at a minimum — can ensure that future needs for housing, critical infrastructure, and other public services will be met under the climate change challenges coastal cities are facing.

Case Study: The Alewife District

Located in the far northwest corner of the city, Alewife is known as the "last frontier" for new development in Cambridge. It has undergone rapid change recently, raising widespread concern among residents over traffic, accessibility, and lack of open space. Alewife is also the area of Cambridge most vulnerable to flooding. This confluence of new development pressure, vocal neighborhood opposition, and flood risk make Alewife an interesting case study, demonstrating how difficult, but essential, climate resiliency planning is.

While Cambridge is known for its walkable neighborhoods and welcoming architecture, the Alewife district feels far from citified. Originally a manufacturing hub, it has shifted to office and residential uses since the 1970s, with a dramatic increase in new housing development in the last decade or so. That boom has ignited tensions between the city government and longtime residents.

Although Alewife is the farthest Cambridge neighborhood from the coast, the recent Cambridge Climate Change and Vulnerability Assessment showed that expected sea-level rise over the next several decades will cause storm surges to flow up the Mystic River and Alewife Brook, flooding the area. By 2070 much of Alewife will have a 20 percent chance of flooding each year. A one-percent-chance storm in 2070 is likely to result in three-foot-deep flood waters.

High heat levels are another threat. Historically, Cambridge summer temperatures average a comfortable 73 degrees Fahrenheit. However, Cambridge summer ambient air temperature is headed to an average of 90 degrees. The heat island effect from the parking lots and other paved surfaces that dot Alewife is likely to add another 10 degrees. In the 2070s, ambient air temperature may regularly top 103 degrees in the Alewife neighborhood.

For these reasons, Alewife is the pilot neighborhood for the citywide preparedness and resiliency planning effort, which builds on Cambridge's Climate Change Vulnerability Assessment. Initiated in 2012 and completed in 2017, the vulnerability assessment was a joint effort among the departments of Community Development, Public Works, and Public Health. It evaluates flooding risks, vulnerabilities from increased heat, and critical infrastructure threats posed by future climate impacts.

Climate Change Preparedness and Resilience Plan

The citywide Climate Change Preparedness and Resilience Plan is expected to be completed by the end of 2018. The full plan will include strategies for preparing and educating community members, adapting existing buildings and requiring new construction to take account of future flooding risks, incorporating resilient infrastructure systems, and enhancing natural ecosystems. It will also be part of the city's efforts to achieve its net-zero-emission goal.

As a first step, the Cambridge Community Development Department released a 70-page draft Alewife preparedness plan last November. The plan and an accompanying handbook of adaptation strategies is available at cambridgema.gov/climateprep. A key feature of the draft is a proposed requirement that all new buildings be elevated at least four feet, raising the first floor of those structures above the projected 100-year flood level in 2070. An added benefit is that this would promote more active street life, as seems to have been the case with similarly designed buildings in Portland, Oregon.

The Alewife preparedness plan includes four categories of interventions.

PREPARED COMMUNITY calls for cooling centers and emergency response plans that will help prepare residents and institutions live through future storms.

ADAPTED BUILDINGS features the elevation requirement, including the use of flood-resistant construction materials, construction of external floodwalls, introduction of backwater valves, and locating building mechanical systems on upper floors.

RESILIENT INFRASTRUCTURE focuses on protecting the area's drinking water, electrical grid, Massachusetts Bay Transportation Authority station, and sewer system.

RESILIENT ECOSYSTEMS focuses on creating new green spaces and reducing the amount of impervious pavement within the neighborhood.

The final CCPR plan for Cambridge will likely feature the same four categories of strategies, but at a citywide scale. That plan is not, however, the only planning effort that will determine how resilient Cambridge will be to future climate impacts.

Cambridge is simultaneously undertaking another monumental planning effort called Envision Cambridge, the city's first comprehensive master plan update in decades. This three-year effort is intended to create a new city zoning ordinance and a multiyear infrastructure investment plan. Ideally, the resilience plan will inform Envision Cambridge's zoning changes and infrastructure choices and ensure that the master plan considers climate vulnerabilities beyond its current 2030 time horizon.

Stuck stakeholders

The Envision Cambridge and CCPR planning efforts for Alewife have taken account of the views of many stakeholders. Perhaps not surprisingly, the groups involved didn't always agree. Public meetings last spring and fall were intended to help the city's planners increase public engagement in climate preparedness planning. However, residents used these meetings (and other events) to push the city to restrict new development within Alewife. Our MIT team interviewed Cambridge planners, residents, and elected officials to better understand their concerns.

PLANNERS

City planning staff expect additional new development within the Alewife District. While undoubtedly very concerned about the likely impacts of climate change, they do not see those threats as a reason to constrain future growth. Rather, they see resilience being achieved through careful adaptation planning that accommodates storm surges, such as elevating new buildings, adding flood storage capacity inside new developments, installing additional green spaces, and perhaps implementing district energy.

The Cambridge planning staff suggested that a moratorium on development — as residents have urged — is neither politically viable nor likely to alleviate climate-related risks. They do believe that offering incentives to private land holders could induce land-use changes that increase resiliency. Many such incentives are enumerated in the Alewife preparedness plan.

RESIDENTS

Local residents expressed genuine, and often long-standing concerns, about their neighborhood. Many want a moratorium on development — or at least a guarantee that traffic congestion and scarce open space will be addressed before further development is allowed. Some expressed alarm at the projected depth of flooding forecast in their neighborhood, and used climate vulnerability as a key justification for halting all new development. They were also very skeptical of the city's elevated building proposal and some of its other resilience strategies, such as "sheltering in place." They believe that most future residents will attempt to evacuate during a storm and be caught in the resulting traffic.

CITY COUNCILORS

Elected officials shared many of the Alewife residents' concerns and seemed quite worried about flooding risks. But, they were pessimistic about the likelihood of a moratorium passing. They also recognized that the tax revenue generated by new development is crucial, leading them to seek ways of using new development to implement climate resiliency measures, including through incentives or even mandates.

City Councilor Craig Kelley made a prescient comment during his interview: Cambridge should not conflate its analysis of flood risks with concerns over development. Unfortunately, that appears to be exactly what is happening in the Alewife district. Two sides with strong preferences are using climate vulnerability to support their preexisting preferences.

At the heart of this case study and in similar debates going on elsewhere is contention over what "resilience" really means. Is an area resilient if its buildings are constructed to accommodate floods? Can residents be persuaded to "shelter in place" when floods occur? At what point does a commitment to "resiliency" require restricting development or returning an area to its original wetland habitat? These are vital questions that require normative judgments about the ideal use of land.

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Case Study: South Boston Waterfront

Like Alewife, many of Boston's "edge" districts are undergoing rapid development fueled by population growth and economic transformation. Between 2010 and 2017, Boston's population grew twice as fast as the rest of the nation, and the city is expected to add another 70,000 people and reach a population of 724,000 by 2030.

A site of gentrification and escalating property values, South Boston has been the focus of redevelopment efforts for more than a decade. Planners have identified South Boston — which includes the South Boston Waterfront (also known as the Seaport or Innovation District) and the Fort Point Channel Landmark District — as a priority site for new mixed use development.

South Boston is a focal point in Imagine Boston 2030, the city's first complete master plan update in a half-century. It is also highlighted in Climate Ready Boston, the city's first comprehensive climate vulnerability assessment, which points to South Boston as one of the city's most vulnerable neighborhoods to flooding.

Economic and population growth has created both challenges and opportunities. In the coming years, South Boston is likely to become a living laboratory for urban design innovation that tries to take account of climate vulnerability and increase resiliency beyond the status quo.

Climate Ready Boston

The 2016 Climate Ready Boston report is the product of a multiyear effort to document climate change risks, including extreme heat, stormwater flooding, and coastal and riverine flooding. It also looks at even more localized impacts. South Boston was one of the eight neighborhoods receiving such scrutiny.

The report makes clear that lives, homes, and businesses are at stake. Under a near-term nine-inch sea-level rise scenario, coastal storms could displace more than 1,600 people living in South Boston's flood-prone area. With 36 inches of sea level rise — the highest scenario considered in Climate Ready Boston — between 10,000 and 12,000 people could be displaced. In 2030, a 100-year flood event could inundate 25 percent of the neighborhood, and up to 70 percent of the area in 2070.

The Climate Ready Boston report was the first step in a long-term effort to raise awareness of the impacts of climate change. While the report identified vulnerable sites, planners and scientists argue that additional hydrological modeling is necessary before the city can plan precise resiliency interventions.

"The areas that get flooded are somewhat intuitive, but if you want to do real management, you really need to know how deep it's going to be, how long it's going to be flooded, and what the probability of flooding is," says Paul Kirshen, academic director of the UMass Boston Sustainable Solutions Lab and a member of the Climate Ready Boston project team. The report "is not the definitive plan for Boston. It is a phase one vulnerability assessment."

More targeted information is on the way, including the Boston Department of Environment's neighborhood-specific assessments. The forthcoming Climate Ready South Boston plan, slated to be released this summer, will enumerate policy and flood-protection measures aimed at reducing risk levels there.

At the same time, as heightened vulnerabilities become clearer, development keeps coming. Between 2010 and 2013 the South Boston Waterfront was the fastest growing urban area in Massachusetts, adding roughly 10 million square feet of new development.

That growth will continue. The strategic goals of the city's new master plan include encouraging the growth of mixed use neighborhoods and developing a 21st century waterfront that creates jobs while reducing the city's vulnerability to climate risk. A lot of residential and mixed use development is planned, and much of it targets flood-prone areas of South Boston.

As a former industrial and working-class neighborhood located primarily on filled-in mudflats, South Boston is considered by planners to be both climate vulnerable and underutilized. Some officials believe that development might provide an opportunity to improve resiliency through the integration of green infrastructure, open space, and innovative building techniques.

Climate Readiness in Planning and Development in Boston

Many of the country's major coastal cities are struggling to figure out how to respond to climate vulnerability while simultaneously promoting development, so Boston is not alone. In some sense, it may even be a national leader. Big investments in vulnerability assessments and efforts to integrate climate resilience considerations into permitting and development review have made Boston a test bed of sorts. We will have to see what can be learned.

Development pressure and the promotion of mixed use development make a moratorium on development or significant downzoning in South Boston politically far-fetched. The area will continue to develop and densify, and that means creative tools and solutions will be needed.

One possible tool is incentive zoning, in part because it helps get around a significant legal barrier. Massachusetts's statewide uniform building code is intended to ensure consistency and prevent a patchwork of jurisdiction-specific regulations. In the age of climate change, however, the building needs in areas threated by future floods differ dramatically from those of inland neighborhoods.

"Some towns would like building elevations to be higher than the baseline elevation by more than a foot, but they can't require that," says Martin Pillsbury, environmental director of the Metropolitan Area Planning Council. "These codes were developed years ago when resiliency wasn't in the picture. It restricts the ability of towns to innovate at the local level."

An early innovator, Boston began developing a framework for resilience-based incentive zoning in 1996 when it added Article 80 to its zoning code. Article 80 gives the city broad authority to determine whether developers of large projects have sufficiently considered a variety of potential impacts.

In 2013, Article 80 was amended by then Mayor Thomas Menino to mandate that developers consider present and future climate conditions impacting large projects through the completion of a Climate Resiliency and Preparedness Checklist. The checklist, administered by the Boston Planning and Development Agency, provides scenario-based guidelines for considering the impact of sea-level rise, extreme precipitation, and extreme heat on structures and the long-term safety of inhabitants.

Based on the findings and ongoing work of Climate Ready Boston, BPDA updated the checklist in October 2017, revising scenarios according to the best available data and increasing the sea-level rise scenario to 40 inches above 2000 levels. The updated policy also introduced a new online mapping tool, making site-level critical flood data and projections available to developers. This new tool allows developers to identify the base flood elevation for a specific project site, based on a one-percent-chance storm event under a scenario of 40 inches of sea-level rise. These maps starkly illustrate South Boston's extreme climate vulnerability, identifying nearly the entirety of the Fort Point Channel, South Boston Waterfront, Marine Industrial Park, and Reserve Channel neighborhoods as areas facing a base flood elevation of at least 19 feet.

Boston's Climate Resiliency Checklist and public data tools require and enable developers and their commercial tenants to assess risk on a long-term basis and to consider innovative risk management strategies. The updated checklist recommends building designs that incorporate 24 inches of freeboard for critical facilities and ground floor residential units, or a minimum 12 inches for all other uses. Five years after first unveiling the checklist, BPDA reports that responses prove that developers are increasingly willing to address sea-level rise in their design plans.

Incentive zoning in Boston allows the city to grant additional development rights in exchange for amenities and design changes increasing the resiliency of buildings and the areas around them. Most of the time, the results are expected to exceed state building code requirements.

The new global headquarters of General Electric located in South Boston, for example, will include two renovated, century-old brick warehouses connected to a 12-story, 300,000-square-foot building. In restoring these warehouses, the architecture firm Gensler will take the buildings from six stories down to five so they can elevate the entire site by 4.5 feet, putting the new headquarters just above the 100-year flood level expected by 2070 (36 inches above current levels). GE's campus will also include rainwater collection, rooftop gardens, and about an acre of open space to aid in stormwater absorption.

The GE example suggests it is possible to pair new development with incentives that enhance resiliency. "Greater density could increase the funding available for resiliency," says BPDA senior waterfront planner Chris Busch. AICP. "Having some level of density or mass which increases growth and value can contribute to a public realm that is available to the public and can survive periodic inundation."

Beyond incentive zoning, Imagine Boston 2030 and Climate Ready Boston refer to something called "climate-ready zoning," but what this means is still unclear. Like most municipalities, Boston has an existing flood overlay zone based on Federal Emergency Management Agency flood maps. Unfortunately, these do not take account of future sea-level rise scenarios.

The hope is to develop new flood overlay zones based on expected flooding, but that poses both technical and political challenges. Climate models are probabilistic and limited by substantial uncertainty surrounding the likely effectiveness of mitigation and adaptation measures. Zoning changes based on climate projections are sure to be contentious.

"FEMA is already a lightning rod politically," says MAPC planner Martin Pillsbury, noting that a recent revision of flood maps meant that "many property owners were required to buy flood insurance for the first time ... Just to make everyone elevate one foot along the coast would impose a huge cost."

Currently BPDA is considering a new zoning overlay that would promote resilience through higher base flood elevations, particularly for retrofits of existing buildings in current and future flood zones. However, amendments to the zoning ordinance require a supermajority vote in the city, and it is unlikely that such a consensus could be achieved on controversial protective zoning. In the meantime, new online mapping tools like the base flood elevation projections provided by BPDA allow developers and residents to think through the likely impacts of future flooding, even if they are not currently located in a FEMA flood zone.

Like planners in Cambridge, officials in Boston believe that heightened interest in new development and an injection of private capital might help promote greater resiliency in climate-vulnerable areas. The city is not ready to consider organized retreat from vulnerable areas or even temporary moratorium on new development in vulnerable areas. So its only option is to use new development to promote and underwrite climate adaptation.

More work to do

As in most places in the last half-century, city planning efforts throughout the Boston region have focused on attracting as much short-term private capital investment as possible. While successful economically, the risks of climate disruption make continuing this emphasis on economic growth exceedingly dangerous. Smart master planning that acknowledges climate vulnerabilities and incorporates risk management strategies into land conservation, rezoning, infrastructure investment, tax forgiveness, and related incentives and controls offers the clear path forward.

In one sense, Cambridge and Boston are ahead of the curve, because they are trying to connect a serious vulnerability assessment to master plan revisions. But these plans only look forward to 2030, and the vulnerability assessments only look to 2070. That's too limited a time horizon.

There are some other key aspects missing from these efforts, including evacuation strategies, disaster preparation plans, and widespread community engagement in resiliency decisions.

Simply put, for coastal cities to thrive in the coming decades of climate disruption, a very different approach to updating comprehensive city plans will be required. This new approach will need to take a longer-term time perspective, incorporate detailed vulnerability and resilience analyses in ways that have not been done before, and engage residents in detailed consideration of the gains and losses associated with various risk management strategies. Cambridge and Boston are at least off to a strong start.

Lawrence Susskind is the Ford Professor of Urban and Environmental Planning in the Department of Urban Studies and Planning at MIT, where Anna Doty received her Master of City Planning degree in 2017 and Adam Hasz is a Master of City Planning degree candidate.