Climate Vulnerability Assessment

Climate Vulnerability Assessment 1312 City of Boston: Climate Ready Boston

Climate

Vulnerability

Assessment

As the climate

continues to

change, three

major climate

hazards will

increasingly

impact Boston:

extreme heat,

stormwater

ﬂ ooding, and

coastal and

riverine ﬂ ooding.

Image courtesy of Sasaki

Stormwater ﬂ ooding and extreme heat

are evaluated as frequent or chronic

hazards

that gradually degrade personal

and economic well-being and directly

expose parts of every neighborhood in

Boston. Coastal and riverine ﬂ ooding is

expected to be an acute hazard for much

of the remainder of the century,

experienced through major storm events

with immediate and long-lasting impacts.

Moreover, as sea levels continue to rise,

coastal ﬂ ooding from high tides is

expected to become a chronic hazard,

potentially ﬂ ooding many low-lying

neighborhoods along the waterfront on a

monthly basis. This is in addition to acute

storm events, which are expected to become

more severe and cause greater damage

over time. This chapter, the Climate Ready

Boston Vulnerability Assessment, analyzes

how people, buildings, infrastructure,

and the economy are aﬀ ected by climate

hazards. Vulnerability Assessment ﬁ ndings

are reported at two scales: ﬁ rst, at the city

scale (referred to herein as the Citywide

Exposure and Consequence Analysis);

and second, at the scale of neighborhoods

or groups of neighborhoods, referred to as

focus areas. The Citywide Exposure and

Consequence Analysis includes a discussion

of socially vulnerable populations in the

city: people who are more vulnerable to

climate hazards due to life circumstances

such as poverty, poor health, and limited

English proﬁ ciency. The citywide

assessment also considers the nature of

the three climate hazards, as well as their

separate and diverse expected eﬀ ects on

Boston’s people, buildings, infrastructure,

and the economy. The Exposure and

Consequence Analysis for Focus Areas was

developed to provide deeper insight into

exposure and consequences as a result of

coastal ﬂ ood hazards in speciﬁ c vulnerable

areas within the Boston community. Climate

Ready Boston is able to address coastal ﬂ ood

hazard for coastal focus areas due to the

robust nature of the information available,

quality of evaluation possible at that scale,

and magnitude of expected consequences

throughout this century. The following

focus areas have been examined for coastal

ﬂ ood hazard beyond the details provided at

the citywide scale:

◦ Charlestown

◦ Charles River neighborhoods

◦ East Boston

◦ Dorchester

◦ Downtown

◦ South Boston

◦ South End

An eighth focus area, Roxbury, serves as

an illustrative example of the interplay

of the three hazards reviewed in this

Vulnerability Assessment with multiple

social vulnerability factors and their eﬀ ects

on collective risk and resilience planning.

Both heat and stormwater ﬂ ooding also have the capacity to impact

the city through severe, acute events. Boston currently experiences heat

indexes greater than 90 degrees more than once a year. Over time, the

number of days at which this heat index is reached will continue to grow,

increasing an already chronic issue. Climate Ready Boston evaluates

stormwater ﬂ ooding at the 10-year, 24-hour frequency event, though more

and less severe and frequent events are known to occur. This evaluation is

in line with the assessment led by the Boston Water and Sewer Commission,

as well as the target level of performance for drainage systems within the

City of Boston.

The Charles River neighborhoods include Allston/Brighton, Back Bay,

Beacon Hill, and Fenway/Kenmore. These neighborhoods are expected to

be exposed to overtopping or ﬂ anking of the Charles River Dam.

Each of these hazards impacts the city’s people, buildings,

infrastructure, environment, and economy in different ways.

MAYOR MARTIN J. WALSH

Climate Vulnerability Assessment 1514 City of Boston: Climate Ready Boston

PROCESS OVERVIEW

The Climate Ready Boston Vulnerability

Assessment evaluates three climate hazards

and their plausible changes over time due to

climate change:

◦ Chronic extreme heat

◦ Frequent stormwater ﬂ ooding

◦ Acute and chronic coastal and riverine

ﬂ ooding

Climate Ready Boston developed a

methodology unique to each hazard to evaluate

impacts on people, buildings, infrastructure,

and the economy. Boston’s socially vulnerable

populations, which are less able to prepare for,

adapt to, and bounce back from climate impacts,

received particular a ention.

Methodologies vary for each hazard due to the

quality and granularity of data available. In the

case of extreme heat, for instance, a detailed risk

assessment of infrastructure and the economy is

impractical due to data limitations. Accordingly,

the impacts to people and buildings are the

primary focus. In the case of the stormwater

ﬂ ooding, the evaluation of buildings and

infrastructure is largely qualitative. In contrast,

a rich coastal and riverine ﬂ ooding dataset is

available for multiple sea level rise conditions

and coastal storm ﬂ ood probabilities that can

be used to quantitatively assess exposures,

vulnerabilities, and consequences.

Quantitative results presented in this report are preliminary and are based

on data with inherent uncertainties, as well as generalized assumptions, as

opposed to site-speciﬁ c assessment of assets, structures, and population

present within speciﬁ c buildings. For example, the ﬁ rst-ﬂ oor elevation of a

structure is assumed to be at grade. In actuality, many residential structures are

split, and steps at grade may descend to the ﬁ rst ﬂ oor (potentially increasing

ﬂ ood loss), and other structures may be elevated or ﬂ ood-proofed above

grade. Site-speciﬁ c evaluations of vulnerability are beyond the scope of

this assessment and should be reserved for detailed evaluation of speciﬁ c

adaptation measures. Values should be interpreted as indicators of relative risk

among different areas within the city.

EXTREME HEAT

Heat is a chronic hazard, a stress

that the city faces every year. As

average temperatures rise and

the frequency, duration, and

intensity of heat waves increase,

heat mortality rates will also rise.

Temperatures are hottest in areas

of the city that experience the

urban heat island effect, but on

very hot days, the entire city is

at risk for the health impacts of

extreme heat, especially those

with health or other physical

challenges, such as older adults

or those with medical illness. The

heat will increasingly stress the

city’s energy supply and related

infrastructure as people seek ways

to cool down.

THE VULNERABILITY ASSESSMENT

EVALUATES THESE THREE CLIMATE

HAZARDS:

COASTAL & RIVERINE FLOODING

Coastal and riverine ﬂ ooding is

expected to lead to the most

signiﬁ cant climate hazard

consequences. Flooding will

be concentrated in low-lying

waterfront neighborhoods,

particularly Charlestown,

Downtown, East Boston, South

Boston, and, later in the century,

the South End and Dorchester.

Due to sea level rise, late in the

century, coastal and riverine

ﬂ ooding will affect Boston both

during storm events and during

high tides, which will cause

large-scale ﬂ ooding in some

neighborhoods.

Building upon previous work

by the City, other government

agencies, and private entities,

the Climate Ready Boston

Vulnerability Assessment uses

the best available hazard data,

adjusted in some cases to align

with the climate projection

consensus developed by the

Boston Research Advisory Group

(BRAG), the ﬁ rst component of the

Climate Ready Boston initiative

(see Climate Projection Consensus

chapter, p.01).

The Vulnerability Assessment evaluates 10-year, 24-hour storm

events. It does not evaluate more severe events, like the 100-

year, 24-hour storm events.

FREQUENT STORMWATER FLOODING

The extent of frequent stormwater

ﬂ ooding

is expected to grow

over time, further limiting access

and mobility during ﬂ ood events

across the city. Due to limitations in

available data, this study assesses

frequent stormwater ﬂ ooding

only. Though high-severity, low-

probability rain events are not

assessed, the impacts of frequent

ﬂ ooding are informative to long-

term planning as they can have

broad societal effects and can be

particularly disruptive for people

who already face signiﬁ cant

challenges due to poverty, illness,

or other social vulnerability factors.

Frequent stormwater ﬂ ooding is a

citywide concern in Boston, with 7

percent of the total land area in the

city likely to be exposed to the 10-

year, 24-hour event as soon as the

2050s and 9 percent by the end of

the century. West Roxbury, Allston,

Brighton, East Boston, and South

Dorchester have the largest areas

of land affected by stormwater

ﬂ ooding, while the South End and

South Boston can expect to see

the greatest increase in land area

exposed to stormwater ﬂ ooding

as sea levels rise and precipitation

events become more extreme.

Climate Vulnerability Assessment 1716 City of Boston: Climate Ready Boston

EXPOSURE, VULNERABILITY,

CONSEQUENCES, AND RISK

Exposure signiﬁ es people, buildings,

infrastructure, and other resources (assets)

that are within areas that are most likely to

experience hazard impacts. Nevertheless,

exposure analysis does not provide insight

into the extent or severity of exposure or

even whether the people, buildings, or

infrastructure will experience loss, as it does

not consider site speciﬁ c conditions (e.g.,

building ﬂ ood-prooﬁ ng) that may prevent or

limit impacts.

Vulnerability refers to how and why people or

assets could be affected by a hazard or how

and why the effects could be exacerbated or

limited. Assessing vulnerabilities requires site-

speciﬁ c or demographic information, such as

existing ﬂ ood-prooﬁ ng measures or whether

people have vehicles that could facilitate

evacuation.

Consequence analysis illustrates to what

extent people or assets can be expected

to be affected by a hazard, as a result

of combined vulnerability and exposure.

Consequences are qualitative and

quantitative impacts to exposed and

vulnerable people, buildings, or infrastructure,

and many can be communicated in terms

of economic losses. Categories of loss

quantiﬁ ed for this analysis include direct

physical damages to buildings (including

structure, contents, and inventory damage),

human impacts or stress factors (mental stress,

anxiety, and lost productivity), displacement

costs (the cost to relocate a business or

household as a result of ﬂ ood impacts), and

losses to the city’s economy due to business

interruption. The consequence analysis

also evaluates shelter needs expected as

a result of a coastal ﬂ ood event, but these

consequences are not separately monetized.

Risk is essentially the combination of exposure,

vulnerability, and consequences. Risk is often

deﬁ ned as the product of both the probability

and consequences of an impact and is

expressed in this report as annualized losses.

Climate Factors for Climate

Projection Consensus

Climate Hazards from

Vulnerability Assessment

GEOGRAPHIC VARIABILITY OF HAZARDS

Two climate hazards—extreme heat and

stormwater ﬂ ooding—generally pose similar

threats citywide; thus, the challenges and basic

principles of many preparedness eﬀ orts related to

heat and stormwater hazards remain largely the

same across neighborhoods. In contrast, coastal

and riverine ﬂ ooding hazards vary widely by

neighborhood and throughout time. Possible

adaptations are dependent on the location in

the city, community context and the people

and businesses that reside in the area, the entry

point along the waterfront leading to ﬂ ooding,

variation in topography, and the coastal or riverine

conditions deﬁ ning the ﬂ ood hazard (e.g., the

duration of ﬂ ooding).

Level of detail also varies spatially (e.g.,

neighborhood versus citywide) based on best

available data and methodological approaches by

hazard. Exposure to each hazard is assessed in the

Citywide Exposure and Consequence Analysis.

Coastal ﬂ ood hazard details are further explored

in the Exposure and Consequence Analysis for

Focus Areas, which were selected for additional

assessment at a more granular level due the robust

nature of the information available, quality of

evaluation possible at that scale, and magnitude of

expected consequences throughout this century.

The Roxbury neighborhood has been selected as

a case study example of the interplay of multiple

hazards with multiple social vulnerability factors

and their eﬀ ects on both collective risk and

resiliency planning.

CONNECTING CLIMATE PROJECTIONS TO THE VULNERABILITY ASSESSMENT’S HAZARD ANALYSIS

Climate Vulnerability Assessment 1918 City of Boston: Climate Ready Boston

to understand future UHIs and temperature

severity in Boston areas. Since extreme heat will be

experienced across the city, there are no “exposure”

statistics to report, and focusing only on the

exposure to heat islands would be misleading;

populations and infrastructure across the city will

be at risk of the impacts of ho er temperatures.

Many of the consequences of extreme heat are

not readily quantiﬁ able. Instead, understanding

that loss of life is a severe risk that a city or

community can face, the assessment focuses

on quantifying an increase in heat mortality

and analyzing qualitatively the other

consequences of extreme heat, including

increased morbidity (illness), increased

energy use, and environmental impacts.

STORMWATER FLOODING

For the purposes of this study, frequent stormwater

ﬂ ooding has been assessed using a 10-year, 24-hour

design storm. Changes in frequent stormwater

ﬂ ooding over time were evaluated based on

projected changes to extreme precipitation and

sea level rise but assuming no changes to the

current stormwater drainage system.

Even with

current sea levels and precipitation intensities,

Boston’s existing stormwater drainage system is

designed to handle 4.8 inches of rain in 24 hours

and can become overwhelmed by fairly frequent

rain events (e.g., the 10-year, 24-hour storm,

approximately 5.24 inches of rain in 24 hours

leading to pooling of water on streets and localized

ﬂ ooding. Conveying collected stormwater will

prove even more challenging with the addition

of sea level rise and more intense precipitation.

This design storm was selected because the

Boston Water and Sewer Commission’s (BWSC)

HAZARDS

A description of each of the three hazards

evaluated as part of this Vulnerability Assessment,

the motivation for assessing a given hazard,

the Climate Ready Boston climate projections

analyzed, and hazard data available from previous

studies are outlined below.

EXTREME HEAT

Boston will experience both an increase in

average temperatures and more extreme heat

events. Heat waves can cause risks to health,

but the negative consequences of heat on the

population can be mitigated with eﬀ ective

measures to prepare individuals and communities.

Heat is especially dangerous to those with health

challenges, and it puts strain on the natural and

built environment, including through energy

demands and damage caused by heat expansion

in building and road materials.

This assessment outlines anticipated increases

in average temperature and extreme heat events

and the impact these changes will have on

public health. The Climate Ready Boston Climate

Projection Consensus evaluated data from many

recent studies performed across the northeast;

data sources used include projections for average

temperatures and heat waves, as well as analysis

of the urban heat island (UHI) eﬀ ect.

Locally, a heat wave is deﬁ ned most often

(and for the purposes of this study) as three or

more days in a row with maximum ambient

temperatures greater than 90 degrees Fahrenheit.

The Vulnerability Assessment used data and

projections created as part of the City of Cambridge

Vulnerability Assessment, supplemented by the

Kopp and Rassmussen 2014 projections to best

understand and analyze frequency, intensity,

and duration of extreme temperatures in Boston.

The Vulnerability Assessment uses the Trust for

Public Land’s (TPL) base heat island analysis

While Climate Ready Boston has not analyzed future heat island projections in this

report, Rossi et al. observed a general trend that UHIs tend to remain in place (and

increase in severity) in warmer future scenarios, which were applied in this UHI analysis.

UHI is understood through spatial analysis conducted by the TPL to identify speciﬁ c

localities in Boston that experience higher temperatures than the city average locality

during days with hot temperatures. The TPL maps show relative land surface temperature

data from MODIS/Aqua radiometer satellite (MODIS MYD11A2) from the warmest summer

months. They identify the speciﬁ c locations in urban areas that meet the characteristics

of UHI isotherms and have land surface temperatures averaging at least 1.25 degrees

Fahrenheit above the mean temperature for both day and night scenarios.

Wastewater Facilities Study

used the storm to

conduct a climate assessment; the BWSC data are

the best available set of comprehensive stormwater

ﬂ ooding data throughout the city.

Additionally,

the BWSC data align with the Climate Ready

Boston climate projections for sea level rise (SLR)

and precipitation.

Speciﬁ cally, three BWSC

10-year, 24-hour stormwater ﬂ ood extents were

evaluated citywide.

LIKELY YEARS OF

INITIAL OCCURRENCE

VULNERABILITY ASSESSMENT SLR

(ABOVE CURRENT TIDE LEVELS)

10-YEAR, 24-HOUR

RAINFALL DEPTH

2030S–2050S

9 INCHES 5.6 INCHES

2050S–2100S

21 INCHES 5.8 INCHES

2070S OR LATER

36 INCHES 6.0 INCHES

Due to model and data limitations associated with

the BWSC analysis, stormwater ﬂ ooding exposure

is reported at the citywide scale. The Vulnerability

Assessment estimates direct exposure to buildings

and the residents within those buildings but does

not describe impacts to individual buildings or

infrastructure assets.

Additional qualitative

assessments are made where possible. In contrast,

the available coastal and riverine ﬂ ooding data

allow for an assessment of individual buildings

and infrastructure and a more detailed discussion

both at the citywide and neighborhood scale.

10-YEAR, 24-HOUR STORM

Consistent with the BWSC Wastewater Facilities Study,

the Vulnerability Assessment uses the 10-year, 24-hour

design storm to approximate stormwater ﬂ ooding

extents due to changing sea levels and extreme

precipitation over time.

A 10-year storm has a 10 percent chance of being

equaled or exceeded any given year. A 24-hour

design condition deﬁ nes the duration of intense

rainfall. Though rainfall can be less or more intense,

and the duration can last hours to days, only 10-

year, 24-hour design storm data are available for this

analysis. More intense rainfall, like 100-year events (i.e.,

those with a 1 percent chance of occurring in a given

year), are not considered due to data limitations but

are important to understanding the full spectrum of

vulnerabilities related to stormwater ﬂ ooding.

The analysis assumes that the current stormwater drainage system remains as it is

today, though the Boston Water and Sewer Commission has plans to improve the

system incrementally over time.

Source: Sullivan, John “Climate Adaptation Challenges for Boston’s Water and

Sewer Systems.” Presentation for the National Association of Flood and Stormwater

Management Agencies. October 15, 2014.

Source: Jewell, Charlie, John Sullivan, Bill McMillin. “BWSC Climate Change Risk

Assessment: Findings and Mitigation/Adaptation Strategies for Wastewater and Storm

Drainage.” Presentation for the NEWEA Annual Conference and Exhibit. January 28,

2015

Source: “Wastewater and Storm Drainage System Facilities Plan.” CH2M Hill

Companies, Ltd. Final Report to Boston Water and Sewer Commission. June, 2015.

BWSC examined multiple stormwater ﬂ ooding conditions, including the impacts

of coastal storms on stormwater ﬂ ooding. Because coastal and riverine ﬂ ooding is

addressed separately using the recently developed MassDOT-FHWA analysis data,

the BWSC data carried forward into this Vulnerability Assessment are the stormwater

ﬂ ooding data that combined future sea level rise and extreme precipitation conditions

only.

BWSC Wastewater Facilities Study data considered two climate change scenarios,

B2 (medium) and A1FI (precautionary). For extreme precipitation, the BWSC medium

climate scenario aligns with the BRAG moderate emissions reduction projections, while

the precautionary scenario aligns with the BRAG business-as-usual emissions projections.

See Appendix for a comparison of the ﬂ ood data used in this analysis to current

conditions, as well as a description of system current conditions.

Climate condition and stormwater hazard ﬂ ooding data are the BWSC Wastewater

Facilities Study medium sea level rise scenario for 2035. The exact BWSC sea level rise

value examined is 0.87 feet above 2010 tide levels, in combination with a 10-year, 24-

hour rainfall of 5.55 inches.

Climate condition and stormwater hazard ﬂ ooding data are the BWSC Wastewater

Facilities Study medium sea level rise scenario for 2060. The exact BWSC sea level rise

value examined is 1.71 feet above 2010 tide levels in combination with a 10-year, 24-

hour rainfall of 5.76 inches.

Climate condition and stormwater hazard ﬂ ooding data are the BWSC Wastewater

Facilities Study precautionary sea level rise scenario for 2060. The exact BWSC sea level

rise value examined is 2.76 feet above 2010 tide levels in combination with a 10-year,

24-hour rainfall of 6.03 inches.

Per the BWSC Wastewater Facilities Study: “It is not appropriate to use [these data] for

detailed analysis (i.e., at the community or parcel-level) and [these data] should not be

used as the sole source of ﬂ ood elevation information. It does not necessarily identify

all areas subject to ﬂ ooding particularly from local drainage sources of small size. Users

should be aware that inundation areas are calculated by mathematical models with

precision that is limited to historical calibrations.”

Climate Vulnerability Assessment 2120 City of Boston: Climate Ready Boston

SELECTION OF SEA LEVEL RISE

CONDITIONS

Sea levels, or the difference in elevation between the sea

surface and land surface, have risen in Boston over the past

century due to multiple, complex, and simultaneous processes.

These processes include thermal expansion and ice-sheet melt,

the gravitational effect of ice-sheet melt, ocean dynamics,

and vertical land movement (such as local subsidence).

From 1921 to 2015, the overall trend in sea level rise was

approximately 1.1 inches per decade. From 1990 to 2010,

the average rate increased to 2.1 inches of sea level rise per

decade. This means that Boston’s 2015 sea levels are about 3

inches higher than 2000.

The pace of sea level rise is accelerating. Sea level rise

projections by 2030 are consistent across all emissions scenarios

evaluated in Climate Ready Boston, with likely sea level rise rates

ranging from historic rates to 3 inches per decade (a nearly 50

percent higher rate of increase than the last two decades).

Later in the century, the rate of sea level rise is expected to

further accelerate, with signiﬁ cant variation between emissions

scenarios (see the Climate Projection Consensus for more

information on this topic).

COASTAL AND RIVERINE FLOODING

Coastal and riverine ﬂ ood hazard data used in

this Vulnerability Assessment deﬁ ne estimated

ﬂ ood depths and extents as a result of tide levels,

riverine ﬂ ows, coastal storms, and sea level rise.

The ﬂ ood hazard data were selected to capture a

spectrum of acute events (e.g., severe coastal storms

combined with sea level rise) and chronic ﬂ ooding

(e.g., potential frequent ﬂ ooding due to high tide

and sea level rise alone, without storms).

In order to deﬁ ne a range of possible ﬂ ood

conditions for Climate Ready Boston (higher

probability / lower impact through lower

probability / higher impact), 10 percent, 2 percent,

1 percent, and 0.1 percent annual chance ﬂ ood

extents and depths were generated for three

sea level rise conditions using data provided by

MassDOT-FHWA. The Climate Ready Boston ﬂ ood

data (all four probabilities) for 9 inches

and 36

inches

of sea level rise are largely identical to the

MassDOT-FHWA data, and the data for 21 inches

of sea level rise were created speciﬁ cally for

Climate Ready Boston.

The Climate Ready Boston evaluation also considers

ﬂ ood hazards from high tides and sea level rise

alone—meaning “blue sky” conditions, without

storms. Because the Boston area has a large tide

range, a combined sea level rise and high tide

ﬂ ood exposure evaluation must also consider

the frequency of occurrence of tide levels. This

Vulnerability Assessment combines an average

monthly high tide level

with sea level rise to deﬁ ne

future high-tide ﬂ ooding exposure. Average monthly

high tide is approximately two feet higher than the

commonly used mean higher high water (MHHW,

the average of the higher high water levels of each

tidal day), and lower than king tides (the twice-a-

year high tides that occur when the gravitational

pulls of the sun and the moon are aligned).

• Three sea level rise conditions have been used in the

evaluation: 9 inches, 21 inches, and 36 inches above

current sea levels.

These selected conditions reﬂ ect

a range of sea level rise conditions likely to occur before

the end of the century in the three emissions scenarios

considered.

• By the end of the 2050s, 9 inches of sea level rise is

expected consistently across emissions scenarios and is

likely to occur as early as the 2030s.

• In the second half of the century, 21 inches is expected

across all emissions scenarios.

• The highest sea level rise considered, 36 inches, is highly

probable toward the end of the century. This scenario has

a greater than 50 percent chance of occurring within this

time period for the moderate emissions reduction and

business-as-usual scenarios and a nearly 50 percent chance

for the major emissions reduction scenario.

Climate scenario and coastal/riverine hazard ﬂ ooding data are the MassDOT-FHWA

high sea level rise scenario for 2030. Actual sea level rise value is 0.62 feet above 2013

tide levels, with an additional 0.74 inches to account for subsidence.

The BRAG Climate Projection Consensus report documented sea level changes relative

to a year 2000 reference level, while the Vulnerability Assessment assumes current (2016)

sea levels as a reference level. Current sea levels are about three inches higher than

those in 2000. See the Climate Projection Summary in this report for more information.

Climate scenario and coastal/riverine hazard ﬂ ooding data are the MassDOT-FHWA

high sea level rise scenario for 2070/intermediate sea level rise scenario for 2100. Actual

sea level rise value is 3.2 feet above 2013 tide levels, with an additional 2.5 inches to

account for subsidence.

Data were interpolated from the MassDOT-FHWA 2030 and 2070/2100 data.

Average highest tide for each month in 2015.

Relative sea level rise, including subsidence, is considered in this document. Though

the term “sea level rise” is used throughout the document, this Vulnerability Assessment

is referring to relative sea level rise, and not just rise in sea levels alone. Additionally, in

many graphs and tables, the acronym “SLR” is used.

VULNERABILITY ASSESSMENT SLR

(above current sea level)

LIKELY YEARS OF INITIAL OCCURRENCE

Major Emissions

Reduction

Moderate Emissions

Reduction

Business as usual

9 inches 2030s–2050s 2030s–2050s 2030s–2050s

21 inches 2060s–2100s 2060s–2090s 2050s–2080s

36 inches 2090s OR LATER 2080s OR LATER 2070s OR LATER

These three sea level rise conditions do not

include the worst-case scenarios but instead

together deﬁ ne a likely range before the end

of the century. Though these three scenarios

are used for qualitative and quantitative

assessment in this study, more severe and even

worst-case sea level rise scenarios should also

be considered as part of future climate-related

studies. Evaluation and design of adaptation

measures should consider that more severe sea

level rise conditions are possible; the BRAG’s

“business as usual” scenario estimates that

seven feet of sea level rise is within the likely

range by the end of the century.

Bosma, Kirk, et al. “MassDOT-FHWA Pilot Project Report: Climate Change and Extreme Weather Vulnerability

Assessments and Adaptation Options for the Central Artery.” MassDOT FHWA Report. June 2015. https://www.

massdot.state.ma.us/Portals/8/docs/environmental/SustainabilityEMS/Pilot_Project_Report_MassDOT_FHWA.pdf.

CLIMATE READY BOSTON SEA LEVEL SCENARIOS COASTAL AND RIVERINE FLOODING

COASTAL FLOOD HAZARD DATA

The majority of the coastal ﬂ ood hazard data created as part of this assessment

are a reanalysis of the coastal ﬂ ood hazard data developed as part of the

MassDOT-FHWA analysis.

In 2015, MassDOT released an analysis of coastal ﬂ ood

hazards using state-of-the-art numerical models capable of simulating thousands

of potential nor’easters and tropical storms coincident with a range of tide levels,

riverine ﬂ ow rates in the Charles and Mystic Rivers, and sea level rise conditions.

The City of Boston used a similar approach and the same technical team as the

MassDOT-FHWA analysis when working with the Federal Emergency Management

Agency (FEMA) in the development of ﬂ ood insurance rate maps (FIRM)

that went into effect on March 16, 2016. The FEMA FIRMs deﬁ ne current ﬂ ood

risk from a regulatory perspective. Nevertheless, the data available from the

MassDOT-FHWA analysis are used in this study because unlike the FEMA FIRMs,

the MassDOT-FHWA data account for sea level rise and other climate related

factors. More details can be found in the Appendix.

Climate Vulnerability Assessment 2322 City of Boston: Climate Ready Boston

Observation Data from NOAA Gauge Observations (Station 8443970 in Fort Point Channel) “Average Monthly High Tide” is an average of the highest monthly tides

JUNE 1–JUNE 15, 2016 OBSERVED WATER LEVELS, BOSTON, MA

PERCENT ANNUAL

CHANCE FLOOD

VERSUS 100-YEAR

FLOOD

A “1 percent annual

chance ﬂ ood” is a ﬂ ood

event that has a 1 in 100

chance of occurring in

any given year. Another

name for this ﬂ ood, which

is the primary coastal ﬂ ood

hazard delineated in FEMA

FIRMs, is the “100-year

ﬂ ood.” Experts prefer not

to use the “100-year” term,

since it gives the impression

that a certain level of

ﬂ ooding will reliably occur

once every 100 years. In

fact, it has a 1 percent

chance of occurring in

any given year and can

even occur multiple times

in a single year or decade,

or it can occur less

frequently. Over a 30-year

period, there is almost a

one in three chance that

a 1 percent annual

chance ﬂ ood will occur

at least once.

Image courtesy of Sasaki

EXPOSURE AND CONSEQUENCES: AN

INTRODUCTION TO THE VULNERABILITY

ASSESSMENT CALCULATIONS

PEOPLE

Boston enjoys a richly diverse population; a key

part of Climate Ready Boston is analyzing how

climate hazards will impact Boston’s residents.

The Vulnerability Assessment quantiﬁ es exposures

to populations as a whole, with an additional

qualitative focus on vulnerable populations

expected to be disproportionately aﬀ ected by

each hazard.

Not all residents are equally able to prepare

for, adapt to, and bounce back from temperature

and ﬂ ood hazards. Those most vulnerable to

current hazards are expected to be impacted

the most as hazards worsen with climate change.

Climate Ready Boston speciﬁ cally considers the

populations in Boston more vulnerable to these

hazards. The Climate Resilience Initiatives chapter

(see p.74) describes options for increasing resiliency

for these groups.

Seven groups who tend to be especially vulnerable

to heat and ﬂ ood hazards have been considered:

◦ Older adults (65+)

◦ Children

◦ People of color

◦ People with limited English proﬁ ciency

◦ People with low to no income

◦ People with disabilities

◦ People with chronic and acute medical illness

These groups are not necessarily independent.

For example, immigrants are often those with

limited English proﬁ ciency.

Each vulnerability

can be thought of as a stressor that the individual

or household experiences, limiting that person or

household’s ability to adapt to and absorb chronic

or frequent stresses from climate hazards (e.g., heat

or stormwater ﬂ ooding hazards) or recover from

acute events (e.g., coastal storm ﬂ ooding).

Data regarding social vulnerability to climate

change face some limitations; it can be diﬃ cult

to diﬀ erentiate between inherent challenges

to socially vulnerable populations and climate-

speciﬁ c challenges and impacts. Similarly,

solutions to create more resilient neighborhoods

often overlap with solutions to strengthen the

community as a whole. In-depth research into

how diﬀ erent social vulnerabilities correlate and

overlap is in somewhat early stages, making it

diﬃ cult to quantify how much belonging to one or

more socially vulnerable group changes the way a

person is aﬀ ected by climate hazards. Overlapping

groups can lead to over-counting; the assessment

quantiﬁ es how many people in one speciﬁ c

vulnerable group live in a neighborhood but not

the total number of vulnerable residents, due to

the potential for one individual to belong to

multiple groups.

In its evaluation of exposure to and consequences

of impact as a result of heat or frequent stormwater

ﬂ ooding, the Vulnerability Assessment takes a

SOCIAL VULNERABILITY

Social vulnerability is deﬁ ned as the disproportionate

susceptibility of some social groups to the impacts

of hazards. These impacts could include death,

injury, loss, or disruption of life or livelihood. Social

vulnerability also affects a population’s resilience:

ability to adequately recover from or avoid

impacts. Vulnerability is a function of demographic

characteristics of the population, as well as

environmental and community conditions such as

healthcare provision, social capital, access to social

networks, and social isolation.

Several studies and methodologies surrounding social vulnerability informed this

analysis, including the Social Vulnerability Index and a 2015 study by Dr. Atyia Martin,

which used advanced Boston-speciﬁ c data to assess how various determinants of

social vulnerability relate to one another (co-occurrences) and to identify primary

variables that capture the full range of vulnerabilities. Source: Martin, S. Atyia. “A

Framework to Understand the Relationship between Social Factors That Reduce

Resilience in Cities: Application to the City of Boston.” International Journal of Disaster

Risk Reduction 12:53–80. 2015.

Ibid.

Climate Vulnerability Assessment 2524 City of Boston: Climate Ready Boston

more qualitative approach, though it also explores

numbers and demographics of people expected

to be aﬀ ected. The coastal and riverine ﬂ ood-risk

evaluation considers potential consequences in

a more quantitative fashion. It looks not just at

the number of people exposed or expected to be

displaced as the result of an event but reviews

expected economic costs resulting from mental

stress and anxiety as well as lost productivity.

Shelter needs expected for each evaluated event

in each sea level rise scenario have been calculated

based on the following factors:

◦ Expected ﬂ ood depths within occupied

structures

◦ Population residing in those structures

◦ The share of the current population within a

given area that is identiﬁ ed as low to moderate

income or as older adults

LOSS CATEGORY LOSSES CONSIDERED DESCRIPTION

STRESS FACTORS

• Mental stress and Anxiety

• Lost Productivity

Natural disasters threaten or cause the loss of

health, social, and economic resources, which

leads to psychological distress. Stress factors are a

product of damage to people’s homes and are

quantiﬁ ed as treatment costs and as lost income.

SHELTER NEEDS

• Number of people and

households in need of

public shelter

Shelter needs for coastal and riverine ﬂ ood events

are calculated as a function of ﬂ ood depth and

certain social vulnerability factors, such as age and

income of the affected population.

DIRECT PHYSICAL

DAMAGES TO

BUILDINGS

• Structure Damage

• Content Loss

• Inventory Loss

Direct physical damages include the destruction

and degradation of buildings as a result of coastal

or riverine ﬂ ooding and are quantiﬁ able as

monetary losses.

DISPLACEMENT

• One time displacement and

relocation costs

Displacement costs are associated with moving

a household or a business to a new location and

resuming activity in that new location.

Mental stress and anxiety calculations are based

on the percent share of the impacted population

expected to seek mental health treatment as a

result of disruption caused by direct physical ﬂ ood

impacts to the structures within which they reside,

as well as the expected costs of such treatment.

Lost productivity

refers to lost work productivity

as a result of mental stress and anxiety alone, and it

is calculated based on expected earnings lost over

time as a result of decreased work productivity or

performance. Both ﬁ gures only consider impacts

for the 30-month period following a ﬂ ood event

and are considered highly conservative (low

estimates), particularly given that results only

VULNERABILITY ASSESSMENT LOSS CATEGORIES

Methodology is detailed in the Appendix and follows process described in FEMA’s

Hazus Flood Technical Manual 2.1. Source: “Hazus Flood Technical Manual.” Federal

Emergency Management Agency. Hazushtt

See Appendix for detailed methodology and sources.

Both mental stress and anxiety and lost productivity are calculated using FEMA

methodologies approved for beneﬁ t-cost analyses to federal funding for mitigation

projects. See Appendix for detailed methodology and sources. Source: “Final

Sustainability Beneﬁ ts Methodology Report.” Federal Emergency Management Agency.

August 23, 2012. /pii/S22124291400119

Values are considered conservative as they only incorporate the percent of the

population expected to seek treatment, as opposed to the entire population expected

to experience mental stress and anxiety. Further, only near-term effects are evaluated.

Refer to the Appendix for a more detailed description of the approach.

consider the portion of the population expected to

actively seek treatment and not all of those who

will likely experience some sort of impairment as

a result of the stress from an event.

Additional consequence calculations related

to the city’s population are captured within the

coastal and riverine evaluations for buildings

and the economy and should be considered when

planning for both the general population and

vulnerable people. Such calculations include

relocation and displacement costs as well as

potential job loss. More information on these

topics is provided below.

BUILDINGS

Climate Ready Boston developed an understanding

of both exposure and potential consequences

of climate hazard impacts to the city’s current

building stock through a number of steps described

in detail in the Appendix and brieﬂ y described

here. First, Climate Ready Boston compiled a

comprehensive building stock inventory from a

variety of sources. The information gathered from

these sources was reconciled and reviewed for

overlap, inaccuracies, and need for clarity. Data

ﬁ elds used for the evaluation were extensive and

include such structure characteristics as location,

footprint, use, number of stories, and real estate

market value. Based on the location, use, size,

and type of structure, analysts developed building

construction and replacement costs,

one-time

disruption costs

for the structure, and expected

contents and inventory

as well as rental rates

and other assumptions that would be needed to

understand potential ﬁ nancial consequences in

the case of ﬂ ood impacts. Grade-elevation data

was combined with the building stock in order

to analyze the extent and depth of ﬂ ooding that

could occur at and within each structure based

on the ﬂ ood hazard data described above.

Flood exposure was determined by cross-

referencing structure location data with

stormwater, coastal, and riverine ﬂ ood hazard

overlays and has been calculated based on

structures shown to currently exist within areas

identiﬁ ed as future ﬂ ood hazard areas. Exposure

results for ﬂ ood hazard can be reported based on

any number of structure characteristics and are

provided in this report by number and type of

structures exposed, exposed square footage, and

real estate market value exposed. Exposure to heat

hazard is pervasive across the city, with higher

heat indexes expected within urban heat islands.

Consequences of coastal and riverine ﬂ ood

damage were evaluated based on depth damage

functions developed by the United States Army

Corps (USACE) for this region following Hurricane

Sa ndy.

Flood depths at each structure are cross-

referenced with depth damage functions that

provide expected percent loss and expected

displacement times (number of days that the

structure is expected to be uninhabitable) for

the structure.

Costs of displacement

and direct

physical damage to buildings were then calculated

based on percent loss and displacement time

combined with structure replacement costs and

disruption costs and rental rates, respectively.

Building replacement values per square foot were obtained by analysts from

RSMeans2016 square footage costs for building types in the Boston area. See Appendix

for more detail.

One-time disruption costs are essentially costs to move people or contents from one

location to another and have been developed using FEMA Hazus values. See Appendix

TBD for more detail.

The contents replacement value is based on the contents-to-structure ratio values

(CSRV) for residential and non-residential structures from data obtained through surveys

in the West Shore Lake Pontchartrain Hurricane and Storm Damage Risk Reduction

Study. Source: “West Shore Lake Pontchartrain Hurricane and Storm Damage Risk

Reduction Study—Final Integrated Feasibility Study Report and Environmental Impact

Statement.” USACE. November 2014.

Based on 2016 local market rates. See Appendix for more detail.

Source: “North Atlantic Coast Comprehensive Study (NAACS).” U.S. Army Corps of

Engineers. http://www.nad.usace.army.mil/CompStudy.

One-time disruption costs are essentially costs to move people or contents from one

location to another and have been developed using FEMA Hazus values. See Appendix

TBD for more detail.

Displacement or relocation costs are calculated based on numerous factors to

include local rental rates, owner occupancy rates, structure ﬂ ood depths, and others.

See Appendix for full methodology.

Climate Vulnerability Assessment 2726 City of Boston: Climate Ready Boston

Consequences of impact from heat- and

stormwater-related ﬂ ood hazards are assessed

more qualitatively based on structure types

and occupancies, as well as lessons learned.

For example, certain structures are more likely

to experience stress to their power supply as a

result of excessive heat.

INFRASTRUCTURE

Infrastructure refers to facilities and assets that

provide a public service to the City of Boston and

its population. Infrastructure may be publicly or

privately owned and operated and include the

following, for example:

◦ Critical facilities, such as water treatment

facilities and generating plants

◦ Transportation infrastructure, such as

roads, bridges, and public transportation

◦ Essential facilities, such as hospitals

and emergency operations centers

◦ Public facilities, such as schools and

civic structures

Climate Ready Boston developed a detailed

asset inventory to capture infrastructure and to

supplement the general building stock described

above. This combined inventory was based on

over 130 separate datasets from a variety of

sources (see Appendix for more detail). This

dataset was merged with the general building

stock, where appropriate, in order to ﬁ ll in data

gaps and conﬁ rm property uses. Members of the

Infrastructure Advisory Group (IAG) supported

the identiﬁ cation of infrastructure assets, as well

as relationships and interdependencies between

diﬀ erent assets and entities, individual and system

vulnerabilities, and existing resiliency measures

in place or planned.

The infrastructure analysis for stormwater

and coastal and riverine ﬂ ooding presents

exposure statistics accompanied by largely

qualitative descriptions of potential impacts

that may result from service interruptions,

including interdependencies between diﬀ erent

infrastructure networks. Due variably to data

limitations or privacy and security concerns, the

Vulnerability Assessment does not include site-

DEPTH DAMAGE FUNCTIONS IN PRACTICE

Example Adapted from FEMA’s Beneﬁ t Cost Analysis Training Unit 3

speciﬁ c information necessary to individually

assess infrastructure vulnerability.

Only direct

physical damages to buildings have been captured

for coastal and riverine ﬂ ood hazard using

the method explained above in the Buildings

section, with potential impacts to service and

line routes (such as transportation, pipelines,

electrical lines) described qualitatively.

Heat

hazard vulnerability is assessed qualitatively

and refers predominantly to impacts on energy

infrastructure as well as public and other facilities

without air conditioning or that may house

vulnerable populations (such as nursing homes

or public housing).

While the focus of this analysis is on impacts to

Boston’s infrastructure, much infrastructure is

systemic in nature and will have broader regional

impacts that need to be considered in future

planning eﬀ orts. Similarly, the impacts of regional

infrastructure on Boston’s people and economy

should be considered in future eﬀ orts.

SUPPORT FROM INFRASTRUCTURE

AND COMMUNITY LEADERS

Infrastructure and community stakeholders supported the

development of the Vulnerability Assessment and climate

resilience initiatives through participation in the IAG and

the Community Climate Resilience Focus Groups.

Infrastructure Advisory Group: IAG members included

representatives from the following:

• Utility companies

• Hospitals, including Medical and Scientiﬁ c

Community Organization, Inc. (MASCO)

• Universities

• Public agencies, such as the Massachusetts Port

Authority (Massport), MassDOT, Boston Housing

Authority, and the Boston Water and Sewer

Commission.

• City agencies such as the Department of Public Works

(DPW), the Parks and Recreation Department (BPRD),

the Boston Transportation Department (BTD), the Boston

Conservation Commission, the Boston Public Health

Commission, and the Commission for Elderly Affairs

Through a series of group planning discussions and

workshops, IAG members supported the process by

providing insight on the greater Boston area infrastructure

(e.g., transportation, utilities, buildings, environmental

and recreational assets, public housing, and schools)

and key interdependencies between different types of

infrastructure. Cascading impacts of interruption in the

transportation network rose as a major concern across

IAG members from all sectors.

Community Climate Resiliency Focus Group: Focus group

members included representatives from the following:

• Community and neighborhood development

corporations (e.g., the Neighborhood of Affordable

Housing [NOAH])

• Government agencies and commissions (i.e., the

Boston Public Health Commission] and the Boston

Elderly Commission)

• 100 Resilient Cities Steering Committee and Working

Group (led by City of Boston Chief Resilience Ofﬁ cer

Dr. Atyia Martin)

Goals included providing input to the Vulnerability

Assessment and Climate Resilience Initiatives and

providing an opportunity for groups to learn from one

another. Discussions focused on community infrastructure,

ongoing resilience work, and opportunities for partnerships

on implementation of community initiatives. Key ﬁ ndings

included the importance of sensitivity around mapping

efforts and the need to be equitable when prioritizing

climate readiness solutions.

It should be noted that calculations typically involve the 10 percent, 2 percent,

1 percent, and 0.2 percent annual chance events. Climate Ready Boston has

substituted the 0.2 percent annual chance event with the 0.1 percent annual chance

event in order to understand impacts at that severity of storm. As such, damage-cost

calculations may be conservative compared to if the 0.2 percent annual chance had

been incorporated.

At a minimum, site-speciﬁ c information needed to make conclusions about asset

or system vulnerability include the critical ﬂ ood elevation and any mitigation or

emergency protection measures in place.

It should be noted that service loss can be quantiﬁ ed.

Climate Vulnerability Assessment 2928 City of Boston: Climate Ready Boston

ECONOMY

Impacts to people, structures, and infrastructure

as a result of climate hazards can also disrupt

the broader Boston economy. Severe impacts can

have regional, national, and even international

consequences. As a result, Climate Ready

Boston has sought to quantitatively capture

the potential impacts of business interruption

within Boston as a result of coastal and riverine

ﬂ ooding, although results are conservative (low

estimates). Calculations use a combination of

expected building restoration times sourced by

FEMA, output and employment values by zip

code for Suﬀ olk County from 2014 (most recent

available data), and input output modeling

through IMPLAN.

Only loss impacts within the

city are considered, and restoration times used

to determine business interruption assume only

ﬂ oors of the structure that are directly impacted

experience disruption. It further assumes that all

businesses will eventually reopen and that all real

estate will return to value production. It reality,

almost 40 percent of small businesses never reopen

following a disaster.

Exposure and consequences to the city’s economy

as a result of heat- or stormwater-related ﬂ ood

hazard is explored qualitatively.

LOSS CATEGORY LOSSES CONSIDERED DESCRIPTION

BUSINESS INTERRUPTION

• Loss of Employment

• Output Loss

Business interruption is associated income lost as

a result of an event that disrupts the operations of

the business or the removal of a piece of real estate,

both rental and sale properties, from the market as

a result of disaster impacts.

REPORTING OF EXPECTED LOSSES AS

A RESULT OF COASTAL AND RIVERINE FLOODING

All loss estimations are reported by imposing

future climate conditions on the present

population and built environment. Neither

population nor development have been projected

into the future.

Loss estimations for people, property, and the

economy presented in this assessment are reported

both as one-time costs by event in total, by loss

category, and as an annualized value for each sea

level rise condition.

Annualized values represent

the total of the product of single losses expected

for each projected sea level rise condition and

its chance of occurring in any given year.

This

method facilitates resiliency planning by allowing

for comparison across areas and events, as well as

expected losses in each sea level rise scenario.

CALCULATING BUSINESS INTERRUPTION CONSEQUENCES

Detailed methodology provided in the Appendix.

Source: “National Flood Insurance Program: Protecting Your Business.” Federal

Emergency Management Agency. http://www.fema.gov/protecting-your-businesses.

Annualized values consider four of the ﬁ ve frequencies considered in this Vulnerability

Assessment, including the 10 percent, 2 percent, 1 percent, and 0.1 percent annual

chance ﬂ ood. Direct damages for each of the ﬂ ood frequencies for one sea level rise

condition were multiplied by their percent chance of occurrence and then added

together to yield the annualized value for one sea level rise condition. Thus annualized

values do not consider frequent ﬂ ood events such as high tides or storms with a chance

of occurrence greater than 10 percent.

Annualized losses should not be interpreted as the losses expected annually. Refer

to the Appendix for a more detailed description of the approach taken to evaluate

damage factors.

PROBABILITY TIMES CONSEQUENCE

Annualizing losses is one method used to “normalize” results of

an evaluation (or even historical losses) in order to communicate

risk. In fact, the deﬁ nition of “risk” is often communicated

as “probability times consequence”; this is exactly how

annualized losses are calculated. Annualized losses can be

used to compare the impacts of different events across time

for mitigation-planning purposes and can even be used to

compare the effects of entirely different hazards (so long as a

probability of impact and costs of such impact can be derived).

Expected relocation costs within the city as a result of 9 inches

of sea level rise (near-term sea level rise scenario) can be used

to illustrate this point:

By annualizing the losses of this event, it becomes apparent

that the risk (probability times consequence) associated with

the 10 percent annual chance event is higher than the lowest

probability event evaluated, despite the fact that one-time

event costs for the 10 percent chance are expected to be

signiﬁ cantly lower. This information informs the resiliency planner

that, in combination with other factors, properties within the 10

percent annual chance ﬂ ood area should perhaps be prioritized

for action prior to those at risk only to lower-probability events.

Risk prioritization should take into consideration a variety of factors.

EVENT

ONE-TIME EVENT

CONSEQUENCES

PROBABILITY

percent annual chance

ANNUALIZED

probability x consequence

10%

high probability

$12,000,000 10% $1,200,000

2% 30,500,000 2% $600,000

lower probability

$35,600,000 1% $400,000

0.1%

very low probability

$155,200,000 0.1% $200,000

Total cannot be calculated - $2,400,000

ANNUALIZATION OF ESTIMATED RELOCATION COSTS FOR THE 9-INCH SEA LEVEL RISE SCENARIO

When the frequency of occurrence is

considered, the total economic cost of high

probability events is signiﬁ cantly higher. These

events have a lower cost each time they

occur, but occur much more frequently.

The one-time economic consequences

are larger for lower probability storms.

Climate Vulnerability Assessment 3130 City of Boston: Climate Ready Boston

SOCIAL VULNERABILITY

KEY VULNERABILITIES

BY POPULATION GROUP

OLDER ADULTS

Older adults (those over age 65) have physical

vulnerabilities in a climate event; they suﬀ er

from higher rates of medical illness than the rest

of the population and can have some functional

limitations in an evacuation scenario, as well as

when preparing for and recovering from a disaster.

Furthermore, older adults are physically more

vulnerable to the impacts of extreme heat. Beyond

the physical risk, older adults are more likely

to be socially isolated. Without an appropriate

support network, an initially small risk could be

exacerbated if an older adult is not able to get help.

CHILDREN

Families with children require additional

resources in a climate event. When school is

cancelled, parents need alternative childcare

options, which can mean missing work. Children

are especially vulnerable to extreme heat and

stress following a natural disaster.

PEOPLE OF COLOR

People of color make up a majority (53 percent)

of Boston’s population. People of color are more

likely to fall into multiple vulnerable groups as

well. People of color statistically have lower levels

of income and higher levels of poverty than the

population at large. People of color, many of whom

also have limited English proﬁ ciency, may not

have ready access in their primary language to

information about the dangers of extreme heat or

about cooling center resources. This risk to extreme

heat can be compounded by the fact that people of

color often live in more densely populated urban

areas that are at higher risk for heat exposure due

to the urban heat island eﬀ ect.

PEOPLE WITH LIMITED ENGLISH PROFICIENCY

Without adequate English skills, residents can

miss crucial information on how to prepare

for hazards. Cultural practices for information

sharing, for example, may focus on word-of-mouth

communication. In a ﬂ ood event, residents can also

face challenges communicating with emergency

CHILDREN

104,659

OLDER ADULTS

63,187

CONCENTRATIONS OF SOCIALLY VULNERABLE POPULATIONS

PEOPLE WITH LIMITED ENGLISH PROFICIENCY

239,246

PEOPLE OF COLOR

327, 2 8 4

176,059

PEOPLE WITH DISABILITIES

70,701

CASES OF MEDICAL ILLNESS

236,938

response personnel. If residents are more socially

isolated, they may be less likely to hear about

upcoming events. Finally, immigrants, especially

ones who are undocumented, may be reluctant to

use government services out of fear of deportation

or general distrust of the government or emergency

personnel.

PEOPLE WITH LOW-TO NO-INCOME

A lack of ﬁ nancial resources impacts a household’s

ability to prepare for a disaster event and to

support friends and neighborhoods. For example,

residents without televisions, computers, or data-

driven mobile phones may face challenges ge ing

news about hazards or recovery resources. Renters

may have trouble ﬁ nding and paying deposits for

replacement housing if their residence is impacted

by ﬂ ooding. Homeowners may be less able to

aﬀ ord insurance that will cover ﬂ ood damage.

Having low or no income can create diﬃ culty

evacuating in a disaster event because of a higher

reliance on public transportation. If unable to

evacuate, residents may be more at risk without

supplies to stay in their homes for an extended

period of time. Low- and no-income residents

can also be more vulnerable to hot weather if

running air conditioning or fans puts utility

costs out of reach.

PEOPLE WITH DISABILITIES

People with disabilities are among the most

vulnerable in an emergency; they sustain

disproportionate rates of illness, injury, and death

in disaster events.

People with disabilities can

ﬁ nd it diﬃ cult to adequately prepare for a disaster

event, including moving to a safer place. They are

more likely to be left behind or abandoned during

evacuations. Rescue and relief resources—like

emergency transportation or shelters, for example—

may not be universally accessible. Research has

revealed a historic pa ern of discrimination

against people with disabilities in times of resource

scarcity, like after a major storm and ﬂ ood.

PEOPLE WITH LIMITED ENGLISH PROFICIENCY

PEOPLE WITH LOW-TO NO-INCOME

176,059

Social vulnerability is deﬁ ned as the disproportionate susceptibility

of some social groups to the impacts of hazards, including death,

injury, loss, or disruption of livelihood.

Numbers show a representation

of citywide populations or cases.

Socially vulnerable populations were mapped by number of people per land acre

in each census tract in the City of Boston. Census tracts whose concentrations of

vulnerable populations in each group fall in the top quartile (25 percent) of census

tracts are highlighted in the series of maps.

For example, research indicates the mortality rate among people with disabilities was

twice that of the rest of the population during the 2011 Japan earthquake and tsunami.

Climate Vulnerability Assessment 3332 City of Boston: Climate Ready Boston

CASES OF MEDICAL ILLNESS

Symptoms of existing medical illnesses are often

exacerbated by hot temperatures. For example,

heat can trigger asthma a acks or increase already

high blood pressure due to the stress of high

temperatures put on the body. Climate events can

interrupt access to normal sources of healthcare

and even life-sustaining medication. Special

planning is required for people experiencing

medical illness. For example, people dependent on

dialysis will have diﬀ erent evacuation and care

needs than other Boston residents in a climate

event.

NEIGHBORHOOD VULNERABILITY

AND CONNECTIVITY

The Vulnerability Assessment analyzes personal

characteristics (like income or race) that heighten

vulnerability in a climate event and also considers

vulnerabilities that occur at a neighborhood

scale. If a neighborhood has less access to a

certain resource, its residents can be even more

vulnerable. Neighborhoods need redundancy

in their resource networks in the same way that

individuals do.

Communities with overlapping vulnerabilities

are at greater risk. Risk is increased even further

in the context of chronically under-resourced

neighborhoods.

Neighborhood connectivity is a signiﬁ cant factor

in community resilience. Neighborhoods that are

less well served by public transit or with fewer

OLDER ADULTS CHILDREN PEOPLE OF COLOR

PEOPLE WITH LIMITED

ENGLISH PROFICIENCY

LOW-TO

NO-INCOME

DISABILITY MEDICAL ILLNESS

COMMUNITY TOTAL POPULATION # % # % # %

# % # % # % # %

Allston/ Brighton 75,000 6,100 8% 4,600 6% 25,400 34%

9,700 13% 21,000 28% 6,200 8% 29,200 n/a

Back Bay/ Beacon Hill 22,600 2,800 12% 1,900 8% 3,600 16%

600 3% 2,600 11% 1,000 5% 9,500 n/a

Charlestown 16,400 1,800 11% 3,300 20% 4,000 24%

1,600 10% 4,200 25% 1,500 9% 6,500 n/a

Dorchester 87,400 8,500 10% 21,000 24% 62,500 72%

35,100 40% 26,600 30% 12,400 14% 31,800 36%

Downtown 30,000 4,100 14% 2,000 7% 9,400 31%

4,000 13% 6,800 23% 2,600 9% 12,400 n/a

East Boston 40,500 4,100 10% 8,700 21% 25,500 63%

17,400 43% 13,700 34% 5,200 13% 14,800 n/a

Fenway/ Kenmore 44,300 2,100 5% 600 1% 14,400 33%

3,700 8% 11,200 25% 2,700 6% 16,000 n/a

Harbor Islands - - - - - - -

- - - - - - - -

Hyde Park 32,300 4,200 13% 7,000 22% 23,200 72%

4,600 14% 5,700 18% 3,800 12% 12,500 n/a

Jamaica Plain 42,100 4,100 10% 6,300 15% 19,200 46%

4,900 12% 14,500 34% 4,200 10% 16,400 n/a

Mattapan 33,700 3,900 11% 9,600 29% 32,100 95%

5,800 17% 11,900 35% 6,000 18% 12,500 n/a

Roslindale 37,700 3,800 10% 7,100 19% 16,700 44%

5,400 14% 6,800 18% 4,100 11% 12,500 n/a

Roxbury 71,600 5,800 8% 16,700 23% 59,200 83%

11,400 16% 27,700 39% 10,400 15% 24,000 n/a

South Boston 31,800 3,200 10% 4,900 15% 7,100 22%

2,600 8% 8,200 26% 3,000 9% 13,500 n/a

South End 38,600 3,300 9% 4,900 13% 16,500 43%

5,800 15% 11,600 30% 4,300 11% 12,800 n/a

West Roxbury 30,400 5,400 18% 6,100 20% 8,100 27%

3,000 10% 3,500 11% 3,000 10% 12,400 n/a

Boston Total 634,400 63,200 104,700 327,300

98,200 176,100 70,700 236,900

Percent of Boston 100% 10% 17% 52%

15% 28% 11% 37%

SOCIALLY VULNERABLE GROUPS BY NEIGHBORHOOD

road connections overall are more vulnerable in a

climate event. If a neighborhood only has one bus

or subway line connecting it to the transportation

system, residents who depend on transit can

more easily be cut oﬀ from their employment or

healthcare. The GoBoston 2030 planning eﬀ ort is

evaluating and planning for Boston’s neighborhood

connectivity.

Neighborhood connectivity spans more than just

transportation access; connections between people

also create more resilient communities. Strong

community organizations reduce risk from social

isolation and connect residents to resources and

information regarding climate change impacts.

Limited access to resources at a neighborhood scale

can also exacerbate social vulnerability. East Boston,

for example, has high concentrations of medical

illness but no hospitals. If the tunnels and bridges

became inaccessible in a ﬂ ood event, those in need

of acute medical care could be less able to access it;

access to much-needed medications has historically

been an issue in large coastal ﬂ ood events.

The daily stresses socially vulnerable residents

face can also make recovery and adaptation more

diﬃ cult. For example, residents living in an area

without a grocery store may have less access to

healthy food. In such areas, classiﬁ ed as “food

deserts,” residents may face challenges to eating

healthily on a daily basis as well as acquiring

adequate food supplies for sheltering in place

in a climate event. Boston’s food deserts include

the Seaport, Roslindale, East Boston, Roxbury, and

West Roxbury.

OLDER ADULTS CHILDREN PEOPLE OF COLOR

PEOPLE WITH LIMITED

ENGLISH PROFICIENCY

LOW-TO

NO-INCOME

DISABILITY MEDICAL ILLNESS

COMMUNITY TOTAL POPULATION # % # % # %

# % # % # % # %

Allston/ Brighton 75,000 6,100 8% 4,600 6% 25,400 34%

9,700 13% 21,000 28% 6,200 8% 29,200 n/a

Back Bay/ Beacon Hill 22,600 2,800 12% 1,900 8% 3,600 16%

600 3% 2,600 11% 1,000 5% 9,500 n/a

Charlestown 16,400 1,800 11% 3,300 20% 4,000 24%

1,600 10% 4,200 25% 1,500 9% 6,500 n/a

Dorchester 87,400 8,500 10% 21,000 24% 62,500 72%

35,100 40% 26,600 30% 12,400 14% 31,800 36%

Downtown 30,000 4,100 14% 2,000 7% 9,400 31%

4,000 13% 6,800 23% 2,600 9% 12,400 n/a

East Boston 40,500 4,100 10% 8,700 21% 25,500 63%

17,400 43% 13,700 34% 5,200 13% 14,800 n/a

Fenway/ Kenmore 44,300 2,100 5% 600 1% 14,400 33%

3,700 8% 11,200 25% 2,700 6% 16,000 n/a

Harbor Islands - - - - - - -

- - - - - - - -

Hyde Park 32,300 4,200 13% 7,000 22% 23,200 72%

4,600 14% 5,700 18% 3,800 12% 12,500 n/a

Jamaica Plain 42,100 4,100 10% 6,300 15% 19,200 46%

4,900 12% 14,500 34% 4,200 10% 16,400 n/a

Mattapan 33,700 3,900 11% 9,600 29% 32,100 95%

5,800 17% 11,900 35% 6,000 18% 12,500 n/a

Roslindale 37,700 3,800 10% 7,100 19% 16,700 44%

5,400 14% 6,800 18% 4,100 11% 12,500 n/a

Roxbury 71,600 5,800 8% 16,700 23% 59,200 83%

11,400 16% 27,700 39% 10,400 15% 24,000 n/a

South Boston 31,800 3,200 10% 4,900 15% 7,100 22%

2,600 8% 8,200 26% 3,000 9% 13,500 n/a

South End 38,600 3,300 9% 4,900 13% 16,500 43%

5,800 15% 11,600 30% 4,300 11% 12,800 n/a

West Roxbury 30,400 5,400 18% 6,100 20% 8,100 27%

3,000 10% 3,500 11% 3,000 10% 12,400 n/a

Boston Total 634,400 63,200 104,700 327,300

98,200 176,100 70,700 236,900

Percent of Boston 100% 10% 17% 52%

15% 28% 11% 37%

“People with limited English proﬁ ciency” = ACS survey respondents who indicated

they speak English less than “very well.”

Health data at the local level in Massachusetts not available beyond zip codes. EASI

modeled the health statistics for the U.S. population based upon age, sex, and race

probabilities using U.S. Census Bureau data. The probabilities are modeled against the

census and current-year and ﬁ ve-year forecasts. “Medical illness” is the sum of asthma

in children, asthma in adults, heart disease, emphysema, bronchitis, cancer, diabetes,

kidney disease, and liver disease. A limitation is that these numbers may be over-

counted as the result of people potentially having more than one medical illness. These

statistics reﬂ ect the number of incidences of each illness, not the number of residents.

Neighborhood percentages are not available due to potential for over-counting.

Food deserts are areas located greater than one mile away from a grocery store.

Source: “Food Access Research Atlas.” USDA Economic Research Service.

Climate Vulnerability Assessment 3534 City of Boston: Climate Ready Boston

EXPOSURE AND

CONSEQUENCE

ANALYSIS

OVERVIEW

The citywide ﬁ ndings of the Vulnerability

Assessment are summarized within this section.

Based on the hazard data and methodologies

previously discussed, the exposures and

consequences of all three hazards are presented

and compared by neighborhood. The ﬁ ndings

for each hazard are organized based on expected

impacts to people, buildings, infrastructure,

and the economy. Where possible, quantitative

analyses were conducted, though due to

limitations in the available data, some ﬁ ndings

only include a qualitative assessment of exposure.

This section includes analyses of the following:

1. Extreme Heat: Public health and other

impacts of rising temperatures

2. Stormwater Flooding: Quantitative and

qualitative impacts on people, buildings,

infrastructure, and economy

3. Coastal and Riverine Flooding: Quantitative

and qualitative impacts on people, buildings,

infrastructure, and economy

EXTREME HEAT

PEOPLE

Heat impacts are some of the most well-

understood, measurable, and preventable impacts

of climate change on human health.

Negative health impacts often accompany extreme

heat. These consequences may include direct loss

of life, increases in respiratory and cardiovascular

diseases, and challenges to mental health. Weather

and climate can also inﬂ uence health stressors,

such as air pollution and vector-borne diseases.

Given the steady rise in temperatures that has been

occurring in Boston—1.8 degrees Fahrenheit since

1970 (see Climate Projection Consensus within

this report)—it is probable that corresponding

health risks will become an even greater challenge

in the future. Climate Ready Boston examined

current climate health risks faced by Boston and

considered how climate change may worsen these

risks. The assessment draws on related assessments

completed over the past several years.

While some health impact pathways are rather

direct—such as the immediate consequences of

CHILDREN AND HEAT ISLAND EXPOSURE

OLDER ADULTS AND HEAT ISLAND EXPOSURE

high temperature or severe storms—most operate

through complex systems involving urban land

use, infrastructure, ecology, and other systems.

Compromised infrastructure can magnify health

vulnerabilities. For example, air conditioning

requires reliable delivery of electricity, which, in

turn, depends on the integrity of the electrical

grid system and associated power-generating

facilities. Access to healthcare services depends

on a functioning transportation system. Thus,

understanding the impact that future extreme

weather events may have on health in Boston

requires considerations of the vulnerabilities of

critical infrastructure systems.

Heat extremes can cause death in addition to

exacerbating chronic health conditions and disease.

Emergency room visits and hospital admissions

increase during heat waves. Consequences of heat

are some of the most well-understood, measurable,

and preventable impacts of climate change on

human health. While everyone is vulnerable

when temperatures spike, some members of

the population are particularly vulnerable,

including older adults (especially if living alone),

the very young, low- and no-income residents,

Some members of

the population are

particularly at risk

when temperatures

spike, including

older adults, the

very young, outdoor

workers, and those

with pre-existing

health conditions.

OLDER ADULTS AND HEAT ISLAND EXPOSURE MEDICAL ILLNESS AND HEAT ISLAND EXPOSURE

The maps above show both daytime and nighttime heat

islands as measured by changes in land surface temperature

across the City of Boston. The dots help show concentrations

of populations vulnerable to heat.

Climate Vulnerability Assessment 3736 City of Boston: Climate Ready Boston

outdoor workers, and those with preexisting

chronic diseases.

In addition to these individual

characteristics, research shows that living in

neighborhoods with less tree canopy leads to

greater risk.

The link between less tree canopy and warmer

temperatures in urban neighborhoods is part of the

“heat island eﬀ ect.” The concept of the heat island

eﬀ ect refers to the higher temperatures observed

in city centers as compared with surrounding

regions; these higher temperatures are particularly

hazardous at nigh ime, when it is important for

the body to cool oﬀ .

Most of the scientiﬁ c evidence on the health eﬀ ects

of heat has focused on increases in daily death

counts during and following extreme heat events.

Even a single day of high temperatures may

increase death rates, but a sequence of hot days,

as in the case of a heat wave, brings even more

risk. Extremes of heat will become more severe and

more prolonged and extend into the spring and fall

seasons, leading to greater exposures of vulnerable

people. This exposure may be exacerbated given

the aging of the population.

Morbidity and mortality eﬀ ects of heat may be

especially severe if the power goes out during an

extreme heat event. Power failures are more likely

during heat waves due to the increased demand

for electric power for air conditioning, as well as

the added stress of the heat on mechanical and

electrical assets. At the same time, air conditioning

provides important protection from exposure to

extreme heat, especially for those who are most

vulnerable. The loss of power during extreme

events, which may be more likely with climate

change, could signiﬁ cantly amplify heat-related

health impacts in the future.

Researchers at Columbia University examined

the potential future health impacts from warming

temperatures by linking together future climate

projections with information on the health

responses that occur in a city when temperatures

increase.

The historical relationship

between

heat and deaths in the summer in Suﬀ olk County,

Massachuse s,

shows that death rates increased

signiﬁ cantly with high temperatures. The analysis

projected future health impacts for future

temperatures in the 2020s, 2050s, and 2080s.

Since climate change will be aﬀ ected by

greenhouse gas emissions now and into the

future, and projected emissions are uncertain,

moderate upper- and lower-bound greenhouse

gas projections were used to drive the climate

models.

The following ﬁ gure shows annual

heat-related mortality rates for Boston.

MORTALITY RATE RELATIVE RISK BY TEMPERATURE

The ﬁ gure shows the way that historical death rates from the baseline

period of 1985–2006 changed as a function of temperature. A relative

risk of 2.0, for example, would indicate that the heat-related mortality

rate for a day of that temperature would be twice as high as a normal

(1.0) day.

Source: Petkova et al., “Projected Heat-Related Mortality in the U.S. Urban

Northeast.” International Journal of Environmental Research and Public Health. 2013.

doi: 10.3390/ijerph10126734.

Using daily data from 1985 to 2006.

Suffolk County includes the cities of Boston, Revere, Chelsea, and Winthrop.

Values derived from a combination of multiple climate studies. See the Climate

Projection Summary in this report for more information.

The high-emissions scenario assumes the continuation of business as usual (no

reduction in greenhouse gas emissions).

50 Source: Kinney et al., “Approaches for Estimating Effects of Climate Change on

Heat-Related Deaths: Challenges and Opportunities.” Environmental Science and

Policy 11, 2008. Note: data for medically ill people double-counts people with multiple

illnesses and thus represents total cases of medical illness of various types as opposed to

a total number of people.

51 Source: Madrigano et al., “A Case-Only Study of Vulnerability to Heat Wave–Related

Mortality in New York City (2000–2011).” Environmental Health Perspectives 123, no. 7.

July 2015.

Mortality rates due to extreme heat

are expected to triple with the

impacts of climate change in Boston.

In the baseline period (1985–2016), heat-related

mortality rates were estimated to be 2.9 per 100,000

people in Boston. During the 2020s, median heat-

related mortality rates for the low and high GHG

emission scenario are expected to be 5.9 and 6.5

per 100,000, respectively.

By the 2050s, Boston

could experience median mortality rates of 8.8

and 11.7 per 100,000, for the low and high scenarios,

respectively. By the 2080s, the median heat-related

mortality rates will increase to 10.5 and 19.3

per 100,000.

Air pollution in Boston is negatively

impacted by rising average temperatures.

Boston currently faces challenges in keeping levels

of air pollution below health-based standards,

especially for ozone and ﬁ ne particulate ma er

(PM2.5). Boston’s challenges with these pollutants

PROJECTED ANNUAL HEAT-RELATED DEATHS PER 100,000 POPULATION

are also related to its position downwind of

much of the urban northeast corridor, along

with power plants and factories throughout

the mid-western states.

Ozone is a strong oxidant gas that occurs at high

levels during the warm half of the year and is

the major contributor to urban smog. Ozone

exacerbates respiratory illnesses like asthma

and has also been linked with premature deaths

in cities. PM2.5 measures the quantity of tiny,

invisible particles suspended in the air due

to emissions from a wide variety of sources.

Combustion of fossil fuels (e.g., from cars, trucks,

furnaces, or power plants) produces large amounts

of toxic PM2.5 emissions. PM2.5 exposure over the

long term contributes to the development of heart

and lung diseases, similar to cigare e smoking.

Baseline

(1985–2016) and

projected future

annual heat-

related mortality

rates for Boston

according to 33

global climate

models and two

greenhouse gas

scenarios.

Climate Vulnerability Assessment 3938 City of Boston: Climate Ready Boston

CHANGES IN LYME DISEASE CASE REPORT DISTRIBUTION

Maps show the reported cases of Lyme disease in 2001

in 2014 for the areas of the country where lyme disease is

most common (the Northeast and Upper Midwest). Both the

distribution and the numbers of cases have increased. (Figure

source: adapted from CDC 2015)

2001

2014

Studies suggest that climate change alone (absent

changes in pollution-precursor emissions) could

lead to higher concentrations of air pollution in

the northeastern United States, especially for

ozone, leading to increasing health risks. Holding

emissions constant, climate changes could worsen

air quality, and health, by up to 5 percent by mid-

centur y.

By reducing emissions from fossil fuel

combustion, we can achieve beneﬁ ts both for

health and for climate.

Changes in average temperatures

can also impact transmission of

vector-borne diseases.

Mosquitoes and the diseases they carry are

highly sensitive to weather phenomena such as

temperature, rainfall, and humidity. For example,

rain provides still water for mosquitoes to breed,

while drought conditions decrease survival; rising

temperatures can enhance the rates of larval

development, adult feeding behavior, and pathogen

development within the mosquito. Climate change

and associated warmer, we er conditions may

increase the risk of vector-borne disease infection,

including Lyme disease. Of particular concern are

potential future impacts related to the diseases

carried by the mosquito Aedes albopictus, which is

present in the northeastern United States but has

not thrived to date because of the constraining

inﬂ uence of cold winters. This mosquito transmits

dengue fever and chikungunya and may also carry

Zika virus.

INFRASTRUCTURE

Boston’s transportation infrastructure

could be at risk from increased frequency,

duration, and intensity of heat waves.

High temperatures can cause steel railroad tracks

to expand. The expansion causes stress to ties,

ballasts, and rail anchors that keep the tracks ﬁ xed

In extreme heat, the air-conditioned built

environment is where the city takes shelter, but our

built environment also faces impacts from heat.

Though the exact impacts of increased temperatures

and increasing frequency, duration, and intensity

of heat waves on energy use in Boston are not

quantiﬁ ed in this report, higher average temperatures

will increase energy use in all building categories. Air

conditioning is energy intensive; if the city’s energy

infrastructure does not keep pace with increasing

demand (especially a more sudden spike in energy

use as a result of a heat wave), then brownouts or

blackouts are probable. Furthermore, this increased

energy usage can strain the individual building

infrastructure of some of Boston’s aging building stock

that may not have adequate electrical capacity for

sufﬁ cient cooling.

Source: Knowlton, Kim et al. “Assessing Ozone-Related Health Impacts under a

Changing Climate.” Environmental Health Perspectives 112 (15): 1557–1563. 2004.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1247621/.

to the ground. Under enough force of expansion,

tracks will buckle in an impact sometimes called

a “sunk kink.” More frequent and severe heat

waves may require track repairs or speed

restrictions to avoid derailments. Many rail

networks require trains to reduce their speed in

temperatures over 90 degrees. With more annual

days over 90 expected in the future, the eﬃ ciency

of the rail system in the city and in the Northeast

Corridor could be impacted.

Thermal expansion can also occur in asphalt

and concrete roads in hot temperatures, causing

roads to buckle. Road buckling is more common

in concrete than in asphalt since it is a less

ﬂ exible material. Buckling is most common in the

early summer months when there is subsurface

moisture. Road buckling is diﬃ cult to predict

and diﬃ cult to prepare for aside from cautioning

drivers to be aware of the road condition and

having repair crews ready. Some bridges and

railroad tracks are constructed with expansion

joints designed to safely absorb heat-induced

expansion of construction materials without

any cracking or buckling. Control joints, on the

other hand—much less expensive than expansion

joints—are strategic cuts in concrete used to allow

any cracking from thermal expansion to occur in

a controlled fashion for predictability and ease of

repair.

Finally, regular road upkeep can be negatively

impacted by construction crews’ ability to work

safely outdoors to maintain roads in the ho er

summer months.

In Boston, this challenge could

be somewhat mitigated by workers being able to

work longer into the winter months.

Increased average temperatures will also impact

natural systems and green infrastructure in

Boston. Natural systems—including the urban

tree canopy, public parks and open space, and

private and commercial green space—play a

signiﬁ cant role in mitigating extreme heat events.

These systems can also suﬀ er from chronic stress

related to increased average temperatures, drought,

and abnormally warm winter seasons.

While tree species near the southern end of their

native range and those which are intolerant of

urban conditions will be particularly stressed,

increased temperatures, mild winters, and

dramatic temperature ﬂ uctuations may disrupt

the seasonal cycles of many species. This would

potentially lead to damage or death. These

stressors can also leave urban forests particularly

vulnerable to pest and pathogens that more freely

proliferate with reduced frost depth and increased

frost-free days.

Heat-related vulnerabilities to the urban tree

canopy and natural systems are a compounding

issue. As rising temperatures lead to a potential

increase in tree mortality, any loss of canopy

coverage or green space will only contribute to

the urban heat island eﬀ ect, reduced air quality,

increased stormwater runoﬀ , and decreased

quality of life.

Source: “The Potential Impacts of Climate Change on U.S. Transportation.”

Transportation Research Board Special Report 290. National Research Council (NRC).

2008.

Source: “Workers at Risk from Excessive Heat.” Occupational Safety and Health

Administration. United States Department of Labor.

Climate Vulnerability Assessment 4140 City of Boston: Climate Ready Boston

STORMWATER FLOODING

Without improvements, the existing

stormwater system will not be capable of

conveying a 10-year, 24-hour rainfall event,

causing untreated stormwater runoff to

pond in the streets. Further, the system

currently struggles to convey the current

10-year, 24-hour rainfall event.

By mid-century, 7 percent of the total land area in

the city could be exposed to stormwater ﬂ ooding

for the 10-year, 24-hour event, with that percentage

increasing to 9 percent by the end of the century.

West Roxbury, Allston, Brighton, East Boston, and

South Dorchester have the largest areas of land

expected to be aﬀ ected by stormwater ﬂ ooding,

while the South End and South Boston can expect

NEIGHBORHOOD

TOTAL AREA

ACRES

2030S–2050S 2050S–2100S 2070S OR LATER

NEIGHBORHOOD 2030S–2050S 2050S–2100S 2070S OR LATER

West Roxbury 3,350 240 240 260

West Roxbury 7% 7% 8%

Allston/Brighton 2,940 200 200 220

Allston/Brighton 7% 7% 8%

Dorchester 3,780 330 360 410

Dorchester 9% 10% 11%

East Boston 3,430 180 210 260

East Boston 5% 6% 8%

Jamaica Plain 2,260 170 180 190

Jamaica Plain 8% 8% 9%

Hyde Park 3,260 170 170 180

Hyde Park 5% 5% 6%

Roslindale 2,250 170 170 180

Roslindale 7% 7% 8%

Roxbury 2,770 170 170 180

Roxbury 6% 6% 7%

Mattapan 1,560 130 130 140

Mattapan 8% 8% 9%

South Boston 1,940 120 150 190

South Boston 6% 8% 10%

South End 640 70 90 160

South End 11% 14% 26%

Charlestown 870 60 60 70

Charlestown 7% 7% 8%

Fenway/Kenmore 620 50 50 60

Fenway/Kenmore 8% 8% 9%

Downtown 770 40 40 50

Downtown 5% 6% 7%

Back Bay/Beacon Hill 460 30 30 30

Back Bay/Beacon Hill 6% 6% 7%

Harbor Islands 820 90 100 120

Harbor Islands 11% 12% 15%

Boston Total 31,720 2,200 2,350 2,720

Boston Total 7% 7% 9%

NEIGHBORHOOD ACRES FLOODED

LAND AREA EXPOSED TO FREQUENT STORMWATER FLOODING UNDER VARYING CLIMATE CONDITIONS

The Wastewater Facilities Study completed by

BWSC has greatly improved understanding of

stormwater ﬂ ood risk in Boston.

Data and insight provided by BWSC has

been instrumental in the completion of the

Vulnerability Assessment and the development

of the resilience initiatives. As discussed in the

Process Overview above, the BWSC’s analysis

of current and future ﬂ ooding for 10-year, 24-

hour rainfall events has provided a foundation

for this Vulnerability Assessment. Though the

BWSC stormwater ﬂ ooding exposure data are

not speciﬁ c enough to approximate structural

damage or other direct consequences, the

data provide ample details to assess areas

impacted by frequent (10-year, 24-hour) and

nuisance ﬂ ooding. Additionally, BWSC has been

an active partner through the Climate Ready

Boston process, providing insights necessary to

develop impactful resilience initiatives.

Top Three Affected by Acres in the Near TermTop Affected by Percentage in the Near Term

Land areas are based on the three 10-year, 24-hour stormwater ﬂ ood extents

developed by BWSC and outlined in the Process Overview section. Sea level rise is

accounted for in future climate conditions.

NEIGHBORHOOD

TOTAL AREA

ACRES

2030S–2050S 2050S–2100S 2070S OR LATER

NEIGHBORHOOD 2030S–2050S 2050S–2100S 2070S OR LATER

West Roxbury 3,350 240 240 260

West Roxbury 7% 7% 8%

Allston/Brighton 2,940 200 200 220

Allston/Brighton 7% 7% 8%

Dorchester 3,780 330 360 410

Dorchester 9% 10% 11%

East Boston 3,430 180 210 260

East Boston 5% 6% 8%

Jamaica Plain 2,260 170 180 190

Jamaica Plain 8% 8% 9%

Hyde Park 3,260 170 170 180

Hyde Park 5% 5% 6%

Roslindale 2,250 170 170 180

Roslindale 7% 7% 8%

Roxbury 2,770 170 170 180

Roxbury 6% 6% 7%

Mattapan 1,560 130 130 140

Mattapan 8% 8% 9%

South Boston 1,940 120 150 190

South Boston 6% 8% 10%

South End 640 70 90 160

South End 11% 14% 26%

Charlestown 870 60 60 70

Charlestown 7% 7% 8%

Fenway/Kenmore 620 50 50 60

Fenway/Kenmore 8% 8% 9%

Downtown 770 40 40 50

Downtown 5% 6% 7%

Back Bay/Beacon Hill 460 30 30 30

Back Bay/Beacon Hill 6% 6% 7%

Harbor Islands 820 90 100 120

Harbor Islands 11% 12% 15%

Boston Total 31,720 2,200 2,350 2,720

Boston Total 7% 7% 9%

PERCENT OF NEIGHBORHOOD FLOODED

All ﬁ gures

presented based

on current

available land.

Any change to

the landscape

from present

conditions, such

as subsidence or

land loss as a result

of sea level rise,

are not taken into

consideration.

to see the greatest increase in land area exposed

to stormwater ﬂ ooding as sea levels rise and

precipitation events become more extreme. Sea

level rise exacerbates stormwater ﬂ ooding issues

by preventing outﬂ ow or even causing backﬂ ow,

resulting in backup of water a empting to ﬂ ow

toward lower ground.

Every neighborhood in Boston will be

exposed to frequent stormwater ﬂ ooding.

Throughout every neighborhood in the city, there

are multiple areas at risk of stormwater ﬂ ooding

for the 10-year, 24-hour design storm, ranging in

size from hundreds of square feet along streets

to multiple city blocks. The largest areas of

stormwater ﬂ ooding generally are concentrated

at low points and in areas with poor hydraulic

conveyance or insuﬃ cient storage capacity. Key

areas include along the coast, where outfalls

may be unable to discharge (sea level rise will

exacerbate such conditions), transportation

corridors with impervious surfaces where water

cannot percolate, and designed drainage areas that

may be overwhelmed. In total, these ﬂ ooded areas

impact large portions of neighborhoods; 5 percent

or more of the land area in each of Boston’s 17

neighborhoods will be exposed to ﬂ ooding from

a 10-year, 24-hour storm as early as the 2030s.

Direct exposure to stormwater ﬂ ooding

increases steadily over time due to climate

change.

This trend is expected for frequent hazards like the

10-year, 24-hour storm and may not be consistent

for other, more severe events. When planning ways

to address stormwater ﬂ ooding, the long-term

rate of expected change in stormwater ﬂ ooding

(including potential planned system upgrades) is

important for implementation timing.

Climate Vulnerability Assessment 4342 City of Boston: Climate Ready Boston

FLOODING FROM 10-YEAR, 24-HOUR STORM WITH VARYING CLIMATE CONDITIONS

LAND AREA EXPOSED TO CHRONIC

STORMWATER FLOODING

Near term

(2030s–2050s)

Mid term

(2050s-2100s)

Late term

(2070s onwards)

Near term (2030s-2050s)

Mid term (2050s-2100s)

Late term (2070s onwards)

Major Roads

Climate Vulnerability Assessment 4544 City of Boston: Climate Ready Boston

Future frequent stormwater

ﬂ ooding will require gray and

green infrastructure investments.

Even with some improvements to the existing

stormwater system, untreated runoﬀ is expected to

pond. According to the BWSC Wastewater Facilities

Study, adding storage to the conveyance systems,

making major upgrades in individual pump station

capacities, or combinations of these alternatives

will improve hydraulics but may not be able to

mitigate stormwater ﬂ ooding in the future caused

by climate change. Further analyses are necessary

to examine the projected severity of ponding for

future climate projections after improvements are

made to the stormwater system.

PEOPLE

Over 85,000 people

currently live in

areas expected to be directly exposed

to frequent stormwater ﬂ ooding by the

end of the century.

Of the existing structures exposed to expected

stormwater ﬂ ooding, 80 percent are either

residential or mixed-use buildings, impacting

tens of thousands of residents and workers in the

exposed buildings and many more that use nearby

streets and open spaces that would be ﬂ ooded.

Stormwater ﬂ ooding can lower indoor air

quality and worsen asthma symptoms.

Because people spend at least 90 percent

of their time indoors, the quality of the air

indoors heavily aﬀ ects health status. Moisture

and air humidity as well as the dampness of

building materials can signiﬁ cantly impact

indoor air quality.

Any residential or commercial structures that

experience ﬂ ooding will face potential long-term

challenges related to mold growth and resulting

respiratory problems. This risk is exacerbated in

buildings that are adjacent to poorly drained soils,

have poorly sealed exterior windows and roofs, or

use forced hot air, which can become a conveyor

of air from damp basement areas.

Some socially vulnerable populations

may face signiﬁ cant challenges with

nuisance ﬂ ooding.

The presence of residential buildings in ﬂ ooded

areas likely translates to nuisance ﬂ ooding, which

rarely damages property but impacts road access

and mobility. Nuisance ﬂ ooding aﬀ ects quality of

life for people in general, with a higher probability

of impacting socially vulnerable populations.

Flooded sidewalks, for example, can especially

impact someone in a wheelchair or someone who

has diﬃ culty walking, making it more diﬃ cult to

get to a bus stop, to work, to a shop for groceries,

or to a healthcare appointment. Flooded roads and

sidewalks also disrupt neighborhood connectivity

and isolate residents from one another,

contributing to social isolation. For populations

burdened with signiﬁ cant stresses and fewer

resource redundancies, this hazard will cause

disproportionate impacts.

BUILDINGS

Without stormwater system improvements,

over 11,000 structures citywide

will

be directly exposed to late-century

stormwater ﬂ ooding as a result of sea level

rise and increased precipitation. Many

more will be indirectly impacted.

Though stormwater ﬂ ooding exposure is primarily

a nuisance and largely does not imply structural

damage even with direct exposure, ponding water

may compromise access to buildings, present

transportation challenges, and damage yards and

other landscaped areas. In addition, buildings

that are still connected to the combined sewer

system may experience wastewater backup issues.

Current building stock in areas expected to be exposed. The change in building stock

has not been projected.

Current population residing in areas expected to be exposed. The population has not

been projected into the future.

Although not evaluated within this Vulnerability

Assessment, rain events more extreme than the

10-year, 24-hour rainfall will have more severe

impacts in Boston, though the impacts would be

NEIGHBORHOOD 2030S–2050S 2060S–2090S 2070S–2100S

Dorchester 1,200 1,260 1,390

South End 1,110 1,320 2,040

Roslindale 880 890 960

Roxbury 870 900 950

East Boston 670 820 1,000

Allston/Brighton 660 660 730

Mattapan 640 670 710

Back Bay/Beacon Hill 530 580 600

Fenway/Kenmore 440 460 490

West Roxbury 420 420 450

Hyde Park 410 420 460

Jamaica Plain 340 350 390

South Boston 340 370 490

Downtown 260 310 350

Charlestown 200 210 240

Harbor Islands <10 <10 <10

Boston Total 8,970 9,610 11,230

BUILDINGS EXPOSED TO FREQUENT

STORMWATER FLOODING BY TYPE

(2070s TO 2100s)

BUILDINGS EXPOSED TO FREQUENT STORMWATER FLOODING WITH VARYING CLIMATE CONDITIONS

BUILDINGS EXPOSED TO CHRONIC

STORMWATER FLOODING

less frequent. Additional analysis on extreme event

ﬂ ooding and the sensitivity to climate change is

recommended for future analyses.

Climate Vulnerability Assessment 4746 City of Boston: Climate Ready Boston

INFRASTRUCTURE

Access and mobility can be impacted

at multiple scales ranging from building

entrances to local streets to major

thoroughfares like highways and

MBTA lines.

Without improvements to the stormwater

management system, frequent stormwater ﬂ ooding

is projected near major thoroughfares, such as

Columbus Avenue, Tremont Street, and Morrissey

Boulevard, as well as Interstates 90 and 93 and

along the MBTA Orange and Red Lines. Because

data resolution is not great enough, this analysis

may not be well suited to accurately reﬂ ect

stormwater ﬂ ooding extents along these MBTA

lines, roadways, and highways. Nevertheless, it is

clear that, at a minimum, the ﬂ ood data highlight

potential nuisance ﬂ ooding at intersections and

onramps providing access to these transportation

routes. Many of these transportation routes are also

designated evacuation routes, which may become

increasingly more ﬂ ood prone to heavy rainfall.

Increased precipitation may impact

emergency response time throughout

the city.

Several hospital campuses, ﬁ re stations, and

police stations are expected to experience frequent

stormwater ﬂ ooding in their vicinity and possibly

within structures in the future, including Carney

Hospital, Massachuse s General Hospital, Boston

Children’s Hospital, Boston Medical Center, and

the Boston Police Headquarters. Impeded vehicle

access to and from such facilities may impact

the timeliness of response vehicles to emergency

situations. Access issues due to stormwater

ﬂ ooding may also impact shift changes—

essential services operate around the clock, and

a delay in shift change could potentially result

in a diminished quality of service due to tired

employees. Every minute counts with essential

services, and extended service time is associated

with increased risk of mortality and harm in health

and safety situations.

ECONOMY

Frequent stormwater ﬂ ooding will

inconvenience customers and discourage

them from using nearby businesses.

Though this analysis does not have suﬃ cient

data to quantify economic impacts, it is expected

that local business may be negatively impacted

by frequent stormwater ﬂ ooding. Around 800

commercial buildings are expected to be within

late-century frequently ﬂ ooded areas, with greatest

concentrations of exposed commercial buildings

located in Downtown and Dorchester. Businesses

can expect brief closures during and after ﬂ ood

events, with the potential for prolonged closure if

there is direct damage to property. Even without

damages to buildings, continued ﬂ ood damage to

parking lots, sidewalks, and landscaping can cause

these assets to deteriorate more rapidly, potentially

contributing to uneven surfaces and negative

appearances that would impact safety, as well as

customer choices.

COASTAL AND RIVERINE FLOODING

The probability of high-impact

storms in the City of Boston is

increasing over time.

Coastal and riverine ﬂ ooding is expected

to lead to the most signiﬁ cant increases in

climate hazard consequences to people,

buildings, infrastructure, and the economy.

Over the course of the twenty-ﬁ rst century,

Boston will become incrementally more exposed

to extensive coastal and riverine ﬂ ooding in

neighborhoods fronting Boston Harbor, Fort Point

Channel, Dorchester Bay, and the Chelsea, Mystic,

and Charles Rivers. Neighborhoods fronting the

coastline, like Downtown, East Boston, and South

Boston, are especially vulnerable currently and

will grow more vulnerable in the coming decades.

Coastal and riverine ﬂ ooding

consequences will increase dramatically

by the middle and end of the century as

storm frequency increases and ﬂ ooding

via new pathways becomes more

probable.

Many areas impacted by lower probability events

(i.e., 1 percent annual chance ﬂ oods) in the early

to mid-century are expected to face exposure to

ﬂ ooding from the monthly highest tides by the

mid- to late century. As sea levels rise in Boston

Harbor, coastal ﬂ ooding is also signiﬁ cantly

more likely to penetrate inland through Fort

Point Channel to much of the South End and

the northern portion of Roxbury. Additionally,

neighborhoods along the Charles River, including

Allston/Brighton, Back Bay/Beacon Hill, and

Fenway/Kenmore, are more likely to face exposure

to ﬂ ooding late in the century when the Charles

River Dam is at a higher risk of being ﬂ anked or

overtopped.

Flood hazard data and adaptation recommendations

developed as part of the 2015 MassDOT-FHWA study

are an essential component of the Climate Ready

Boston analysis.

As discussed in this section and the Focus Areas

chapter, the rich MassDOT-FHWA ﬂ ood hazard

dataset has been critical to quantifying exposure

and consequences. Coupled with the Climate Ready

Boston general building stock and asset inventory, a

comprehensive assessment of coastal and riverine

ﬂ ooding exposure and consequences is possible

within Climate Ready Boston, while creating a

foundation for future studies.

The factors driving risk from coastal and

riverine ﬂ ooding vary greatly along the

waterfront.

Boston could manage much of the coastal ﬂ ooding

projected early in this century by addressing low

points at the waterfront through which water could

penetrate inland. This kind of approach could

be particularly eﬀ ective in Charlestown and East

Boston, where the length of waterfront sections

with low elevations is comparatively limited.

South Boston, in contrast, will be challenged

early in the century even with relatively moderate

increases in sea levels. In this neighborhood,

signiﬁ cant portions of the waterfront serve as

ﬂ ood entry points, so developing strategies to

increase protection would require more signiﬁ cant

investments in infrastructure or more complex

coastal ﬂ ood resiliency planning. Other ﬂ ood entry

points, such as the ﬂ anking of the Charles River

Dam or Fort Point Channel, are likely to require

large-scale infrastructure improvements to reduce

ﬂ ood risk but would likewise result in signiﬁ cant

beneﬁ ts, reducing ﬂ ood exposure across multiple

neighborhoods. See the Protected Shores resilience

initiatives (p.98) and the Focus Areas chapter (p.

148) for more details on potential ﬂ ood protection

systems.

Climate Vulnerability Assessment 4948 City of Boston: Climate Ready Boston

As the sea level continues to rise, the likelihood of major ﬂ oods

will increase from a 1% annual chance to a monthly reality

COASTAL AND RIVERINE FLOOD SCENARIOS

For each of the three sea level rise scenarios considered,

Climate Ready Boston also evaluated expected exposure

and impacts for four modeled ﬂ ood events, as well as the

average monthly high tide (see Process Overview for more

on the average monthly high tide). The modeled ﬂ ood events

coincide with the 10 percent, 2 percent, 1 percent, and 0.1

percent annual chance ﬂ ood events, plus appropriate sea

level rise. The lower probability the event, the higher the

magnitude and severity of impact can be expected from

the storm when it arrives.

PERCENT ANNUAL CHANCE

The 1 percent annual chance ﬂ ood has a 1 in 100 chance

of being equaled or exceeded in any given year and is the

primary coastal ﬂ ood hazard delineated in FEMA FIRMs. Percent

annual chance ﬂ ood elevations do not imply a period of time

between occurrences. Though the chance of occurrence each

year may seem relatively low, a 1 percent annual chance event

could occur multiple times in a given year, decade, or century.

Climate Ready Boston uses a 1 percent annual chance ﬂ ood

nomenclature rather than the “100-year” ﬂ ood, in order to

limit confusion related to the possible time horizon of an event

occurring. The 100-year ﬂ ood event terminology can more

easily be misinterpreted to imply that 100-year events occur

only once every 100 years. In reality, these events have close

to a one in three chance of occurring at least once during a

30-year period.

2030s–2050s: 9 INCHES OF SEA LEVEL RISE

2050s-2100s: 21 INCHES OF SEA LEVEL RISE

Future ﬂ ood extents shown only within City of Boston for all conditions.

Climate Vulnerability Assessment 5150 City of Boston: Climate Ready Boston

Neighborhoods Total

Land Area

(Acres)

9” SLR

1% annual

chance

21” SLR

1% annual

chance

36” SLR

1% annual

chance

36” SLR

AMHT

9” SLR

1% annual

chance

21” SLR

1% annual

chance

36” SLR

1% annual

chance

36” SLR

AMHT

I. Greatest Exposure & increasing throughout century

Charlestown 870 120 310 460 110 14% 36% 54% 12%

Downtown 770 110 240 350 70 14% 31% 45% 10%

East Boston 3,340 540 1,040 1,680 480 16% 30% 49% 14%

Harbor Islands 820 200 230 260 200 25% 28% 32% 24%

South Boston 1,940 470 930 1,220 360 24% 48% 63% 19%

II. Lower Exposure today, but signiﬁ cant jump late century

Allston / Brighton 2,940 30 70 240 20 1% 2% 7% 1%

Back Bay / Beacon Hill 460 <10 <10 80 <10 <1% 1% 17% <1%

Roxbury 2,770 <10 <10 130 <10 <1% <1% 5% <1%

Dorchester 3,780 240 430 750 220 6% 11% 20% 6%

South End 640 <10 20 450 <10 <1% 3% 71% <1%

III. Other Neighborhoods

Fenway / Kenmore 620 <10 <10 <10 <10 <1% <1% <1% <1%

Hyde Park 3,260 0 0 0 0 0 0 0 0

Jamaica Plain 2,260

0 0 0 0 0 0 0 0

Mattapan 1,560

0 0 0 0 0 0 0 0

Roslindale 2,250

0 0 0 0 0 0 0 0

West Roxbury 3,350

0 0 0 0 0 0 0 0

Boston Total 31,720

1,720 3,280 5,630 1,470 8% 10% 18% 8%

PERCENT OF NEIGHBORHOOD EXPOSEDLAND AREA EXPOSED (ACRES)

2070s OR LATER: 36 INCHES OF SEA LEVEL RISE

AREA AND PERCENT OF NEIGHBORHOOD EXPECTED TO EXPERIENCE FLOOD IMPACTS

UNDER THE 1 PERCENT ANNUAL CHANCE FLOOD EVENT IN EACH SEA LEVEL RISE SCENARIO

AMHT is the Average monthly highest tide

Ten percent of Boston’s land area

is expected face exposure to 1

percent annual chance coastal

and riverine ﬂ ooding as soon as

the 2050s. In the late century, this

increases to 18 percent.

As soon as the 2070s, almost 5

percent of Boston’s land area

is expected to face exposure

to inundation from the average

monthly high tide.

East Boston and South Boston have

the most land area affected by

coastal ﬂ ooding and sea level rise.

Climate Vulnerability Assessment 5352 City of Boston: Climate Ready Boston

BACK TO THE FUTURE?

Landmarks nearest the coast, like the Institute

for Contemporary Art, the New England

Aquarium, and Boston Children’s Museum, lie

in some of the most exposed parts of the city.

Faneuil Hall and Quincy Market are slightly

farther inland but without additional actions

are also at risk of ﬂ ooding during future high

tides. Many of the city’s oldest landmarks, such

as the Old State House, Paul Revere House, and

Old North Church, sit on higher ground, above

ﬂ ood risk. Why are many of the Boston’s oldest

landmarks out of the projected ﬂ oodplains?

The relative safety of these older landmarks

reﬂ ects the history of our city: transformed

through centuries of landﬁ ll, the original islands

and peninsula of the city remain higher and

more protected than areas built on ﬁ lled

tidelands. Comparison of Boston’s original

landforms to the 1 percent annual chance

ﬂ oodplain late in the century shows a close

parallel; large portions of the original landforms

in Charlestown, the North End, Downtown,

East Boston, and South Boston remain out of

the coastal ﬂ oodplain even late in the century

while areas that were ﬁ lled over time are at

higher risk of ﬂ ooding from coastal storms.

However, some ﬁ lled areas, like parts of

Columbia Point, were ﬁ lled to higher elevations

and therefore face less exposure to future

ﬂ ooding.

The impacts of climate change are not only

isolated to coastal storms. By late in the

century, the most noticeable changes to our

current landscape will likely be seen during

high tides, which will creep higher and higher

over the decades. By 2100, the extent of future

high tide could be similar to ﬂ ooding caused by

a major storm early in this century.

CITYWIDE LAND ACRES EXPOSED

CITYWIDE POPULATION EXPOSED

PEOPLE

In the late century, 75 percent of

buildings exposed will be either residential

or mixed-use, potentially exposing over

88,000 people (nearly 15 percent of

Boston’s population) to coastal and

riverine ﬂ ooding.

The majority of the more than 88,000 Bostonians

who will be exposed to late-century 1 percent

annual chance coastal storms and sea level rise

impacts reside in four neighborhoods: Downtown,

East Boston, South Boston, and the South End.

Projected future 10-year, 24-hour stormwater

ﬂ ooding for the same time period has similar

building and population exposure statistics.

Nevertheless, coastal and riverine ﬂ ooding is

considered more dangerous, as it is more likely

to result in massive property damage and injury

and can require years for full recovery. Further,

unresolved impacts following coastal storms can

become long-term chronic issues.

For late-century climate conditions, estimates

show that more than 9,000 people in these four

neighborhoods will be in need of public shelter due

to a coastal ﬂ ood. The existing emergency shelters

located in these neighborhoods have a combined

capacity of just over 1,000 people.

All population, structure, and infrastructure exposure ﬁ gures refer to potential future

hazards projected onto current conditions. No projections have been completed for

the purposes of the quantitative analysis due to inherent uncertainty.

Climate Vulnerability Assessment 5554 City of Boston: Climate Ready Boston

At the 36-inch sea level rise condition,

10 percent of Boston’s K–12 schools

are exposed to lower-probability ﬂ ood

impacts.

Closure of these schools as a result of ﬂ ooded

access or direct damage would aﬀ ect over 11,500

current students—15 percent of all of Boston’s

school-age population.

Coastal ﬂ ooding is particularly disruptive

and dangerous for those living in

chronically stressed neighborhoods,

without resources or education for disaster

preparedness and recovery.

Coastal ﬂ ooding will have a signiﬁ cant near-term

impact on socially vulnerable populations living

in waterfront areas like East Boston. Moreover,

with 36 inches of sea level rise, a major coastal

storm will impact even inland neighborhoods

Neighborhood Total AMHT 10% 1% 0.10% AMHT 10% 1% 0.10% AMHT 10% 1% 0.10%

East Boston 40,500 280 820 7,020 16,670 770 9,090 16,700 18,500 6,300 18,180 19,070 20,410

Downtown 30,020 630 2,190 4,680 9,600 860 3,770 9,940 12,810 2,990 11,120 13,950 16,090

South Boston 31,780 100 1,680 2,330 6,400 100 3,090 7,340 9,210 2,270 8,750 10,960 12,260

Dorchester 87,380 0 150 340 5,740 20 3,530 5,100 6,590 160 5,760 6,820 9,700

Charlestown 16,430 350 420 1,340 3,600 350 2,530 3,730 4,750 1220 3,920 5,180 5,540

South End 38,600 0 0 0 230 0 0 240 23,350 0 24,980 27,400 35,940

Back Bay/Beacon Hill 22,600 0 0 0 0 0 0 0 1,920 0 10 4,630 13,650

Roxbury 71,580 0 0 0 0 0 0 0 720 0 1060 1,830 3,590

Allston/Brighton 74,990 0 0 0 0 0 0 0 190 0 0 190 2,380

Fenway/Kenmore 44,260 0 0 0 0 0 0 0 0 0 0 60 31,400

Harbor Islands 0 0 0 0 0 0 0 0 0 0 0 0 0

Hyde Park 32,310 0 0 0 0 0 0 0 0 0 0 0 0

Jamaica Plain 42,070 0 0 0 0 0 0 0 0 0 0 0 0

Mattapan 33,680 0 0 0 0 0 0 0 0 0 0 0 0

West Roxbury 30,440 0 0 0 0 0 0 0 0 0 0 0 0

Roslindale 37,720 0 0 0 0 0 0 0 0 0 0 0

Boston Total 634,440 1,360 5,260 15,700 42,250 2,110 22,010 43,060 78,055 12,930 73,790 90,080 150,950

9” SLR (2030s - 2050s) 21” SLR (2050s - 2100s) 36” SLR (2070s or later)

POPULATION EXPOSED BY SEA LEVEL RISE CONDITION

like Roxbury and portions of Dorchester. This

is a concern because of the multiple layers of

vulnerability that these neighborhoods are

already facing.

The risk of major storms is very diﬃ cult for

members of the population to conceptualize if

they have not experienced one in their lifetime. As

such, risk may be underappreciated, and residents

may fail to prepare adequately or evacuate

on time. In communities with lower levels of

education and income, people may simply lack

the resources to adequately prepare. Additionally,

large-scale ﬂ ood defense infrastructure can result

in a false sense of security for some communities;

ﬂ ood defense systems, like in New Orleans, can

never fully eliminate risk of inundation, making

multiple mitigating lines of defense, as well as

preparedness and evacuation measures, vitally

important. Such factors together exacerbated

impacts of Hurricane Katrina in Louisiana in 2005.

Percentage of all schools mapped by Climate Ready Boston thus far.