ASSESSING THE VULNERABILITY OF TAMPA BAY COMPREHENSIVE CONSERVATION & MANAGEMENT PLAN GOALS

TO THE EFFECTS OF A CHANGING CLIMATE

MAYA BURKETAMPA BAY ESTUARY PROGRAM

TBEP TECHNICAL REPORT #10B-17

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ASSESSING THE VULNERABILITY OF TAMPA BAY COMPREHENSIVE

CONSERVATION & MANAGEMENT PLAN GOALS TO THE EFFECTS OF A

CHANGING CLIMATE

Introduction

The Tampa Bay Estuary Program (TBEP) was established in 1991 as part of a national network of 28 estuary

programs administered by the US Environmental Protection Agency (EPA). The TBEP was charged with

developing and implementing a plan to guide the protection and restoration of Tampa Bay between partners

at various levels of government: Hillsborough, Pinellas and Manatee counties (later Pasco County); the cities

of Tampa, St. Petersburg and Clearwater; the Southwest Florida Water Management District; the Florida

Department of Environmental Protection; and EPA. In 1998, these and other partners signed an Interlocal

Agreement, pledging work together to achieve the goals of the newly completed Comprehensive

Conservation and Management Plan (CCMP) for Tampa Bay.

Tampa Bay is a large, urbanized open-water estuary on the west central coast of Florida, spanning nearly 400

square miles and supporting a population of three million residents. Over the past century, land use practices

and economic development activities have resulted in extensive changes to the shoreline, bay bottom,

patterns of circulation, and to the suite of habitats present throughout the watershed. The CCMP establishes

an adaptive framework to restore ecologic function of the estuary given these conditions and is foundational

to accomplishing the mission of the TBEP. The CCMP identifies specific, measurable goals for bay

improvement in several core areas: Water & Sediment Quality, Bay Habitats, Fish & Wildlife, Dredging &

Dredged Material Management, Spill Prevention & Response, Invasive Species, Public Involvement and

Education, Public Access and, beginning in 2012, Climate Change.

Initially, climate-related CCMP actions sought to address the effects of sea-level rise on coastal habitats. This

emphasis reflected existing research priorities and a formal policy statement acknowledging locally-

documented increases in sea levels, likely threats to coastal habitats and fish and wildlife resources, and the

particular role of the TBEP in research, technology transfer and public education. As a participant in the EPA

Climate Ready Estuaries program, the TBEP developed a decision support tool for resource managers and

land use planners to visualize possible sea-level rise scenarios through 2100; compiled the “Gulf Coast

Community Handbook” to share examples of how communities around the Gulf of Mexico are

accommodating climate change in their habitat restoration projects; curated a collection of images

documenting extremely high “king tides” to help citizens envision how sea-level rise might affect structures

and shorelines; and implemented a long-term monitoring program to assess plant community and other

ecologic and functional changes in critical coastal habitats.

More recently, the TBEP has expanded its efforts to understand how the effects of climate change are

experienced locally in Tampa Bay, initiating projects to quantify the value of the bay’s salt marshes,

mangroves and seagrass beds in storing carbon and reducing greenhouse gas emissions, and establishing a

high-resolution pH monitoring site within the bay to assess whether seagrasses may buffer the effects of

global ocean acidification trends. Although this research has been incorporated into the most recent CCMP

(2017 Update), other climate stressors, such as increasing air and water temperatures or changing

precipitation patterns, are not addressed in a systematic way.

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In many cases, the goals of the CCMP expressly adopt science-based numeric targets for restoring Tampa

Bay’s living resources to meet conceptual goals identified by citizens and quantified by the technical and

management community. These targets are critical milestones for measuring the success and effectiveness of

the TBEP and have served as a useful rallying point to promote collective action to improve the health of

Tampa Bay throughout the region. Both the technical scientific community and local policy makers have

acknowledged that the myriad of impacts associated with climate change may adversely affect the

community’s ability attain the environmental goals it has set forth in the plan. The purpose of this

vulnerability assessment is to evaluate the extent to which the management goals of the CCMP are vulnerable

to a variety of climate stressors and, using regionally-relevant climate research, establish an adaptive resilience

framework for future adaptation or mitigation activities to ensure the protection and restoration of Tampa

Bay and its watershed for generations to come.

Methods

This vulnerability assessment closely follows the process (Figure 1) outlined in “Being Prepared for Climate

Change: A Workbook for Developing Risk-Based Adaptation Plans,” which aims to build the capacity of

local and regional organizations to attain their

programmatic goals while effectively planning for

and responding to climate change impacts. The

assessment (steps 1-5) employs a risk

management approach to evaluate the CCMP

goals and better understand the extent to which

successful accomplishment of those goals may be

threatened by specific climate stressors. The

recommendations developed as a result of this

collaborative assessment process will lay the

groundwork for future revisions to the actions

and strategies incorporated into the CCMP to

ensure that goals sought by the local community

remain attainable given changing climate

conditions (steps 6-10).

Step 1: Communication and Consultation

The Tampa Bay region has an active resource management community and a variety of networks involved in

climate adaptation planning. Rather than convening a new stakeholder group to conduct this assessment,

experts were primarily engaged through three existing forums: the TBEP Technical Advisory Committee, the

Agency on Bay Management, and the Tampa Bay Climate Science Advisory Panel. The TBEP Technical

Advisory Committee includes the scientific and technical staff of local, regional, state and federal agencies

involved in monitoring, managing or protecting Tampa Bay, university researchers, and private sector

representatives with scientific or technical expertise that assist TBEP in evaluating complex environmental

issues involving Tampa Bay and in implementing bay restoration and protection goals. The Agency on Bay

Management is the natural resources committee of the Tampa Bay Regional Planning Council and is an

association of representatives from the recreational, commercial fisheries, industrial, regulatory, academic and

scientific sectors, local, regional, state and federal governments, and legislators. The Agency has served as a

Figure 1. A process roadmap from “Being Prepared for Climate Change” showing Step 1 through Step 5 of the vulnerability assessment and Step 6 through Step 10 of action planning.

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broad-based forum for open discussion of the myriad issues involving the estuary, and as a voice for

protection, restoration, and wise use of the bay by the entire region since 1985. The Tampa Bay Climate

Science Advisory Panel is an ad hoc network of scientists and planners convened by Florida Sea Grant

working collaboratively to support local governments in the Tampa Bay region plan for a changing climate.

The Climate Science Advisory Panel published a Recommended Projection of Sea Level Rise in the Tampa

Bay Region to guide local government adaptation planning and generally promotes the pragmatic application

of scientific data in public policy. Collectively, these groups cover a broad cross-section of relevant actors

familiar with climate change impacts throughout the Tampa Bay watershed.

In-person meetings were held in July 2016, September 2016, and January 2017 and were focused on

establishing context, identifying risks, and evaluating risks, respectively. An assortment of techniques were

employed to collect input from stakeholders, including facilitated discussions, joint fact-finding, written

communications, one-on-one interviews, literature review, and “Poll Everywhere” live polling technology.

Step 2: Establishing Context

Initial facilitated discussions resulted in several key points of consensus regarding the scope of the

assessment. First, stakeholders agreed that the assessment would not attempt to inventory an exhaustive list

of plausible natural resource impacts likely to occur as a result of changing climatic conditions; nor would it

attempt to broadly characterize environmental outcomes at a watershed scale since many of these analyses

have already been performed for the Tampa Bay region (Sherwood and Greening 2014, Department of

Homeland Security 2015, CSAP 2015). Instead, the vulnerability assessment builds upon existing efforts to

characterize climate stressors throughout the watershed and is focused on the evaluating the extent to which

the eighteen individual resource management goals included in the 2017 update of the CCMP (Table 1) are

susceptible to specific climate risks.

Table 1. CCMP Goals (2017 Update)

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Finally, stakeholders reviewed the suite of climate stressors included in the National Climate Assessment

(NCA) and the Climate Change Indicators in the United States and determined that the assessment should

address the risks associated with the following climate stressors most likely to affect the Tampa Bay

watershed:

Sea-level rise

Increased air and water temperatures

Extended frost-free season

Storminess (extreme rainfall, hurricanes)

Drought

Ocean acidification

Step 3: Risk Identification

Plausible risks associated with the previously agreed upon

climate stressors were considered for each CCMP goal (Figure

2). Given the ecological complexity in natural systems and the

potentially far-reaching effects of climate change, discourse

was structured to discourage stakeholders from conjuring

elaborate and confounding climate sceanarios for the region

and instead focus on the discrete goals for which the TBEP

and its partners are responsible. Stakeholders were presented

with a goal, several examples of possible stressors and risks

relevant to its outcome, and then encouraged to offer insights,

additions, or corrections to the information presented. These

vigorous facilitated discussions identified the nearly fifty

climate-related risks challenging successful implementation of

CCMP goals, shown below in Table 2.

Figure 2. Risks were identified in context of specific CCMP goals and mutually agreed upon climate stressors.

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Table 2. CCMP Climate Change Vulnerability Assessment – Risk Identification

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Step 4: Risk Analysis

A literature review of best available, regionally-applicable scientific data was conducted to analyze the

likelihood and confidence associated with climate stressors and related risks.

Stressor: Sea-level rise

Likelihood: High

Data measured at the St. Petersburg tide

station shows that water levels in Tampa

Bay have increased approximately 6.6 inches

or approximately 1 inch per decade (Figure

3, CSAP 2015) since measurements began

being recorded in 1946. This rate of sea-

level rise is consistent with global sea-level

trends, which are predicted to continue to

increase into the next century. The Tampa

Bay Climate Science Advisory Panel

concludes that the region is likely to

experience somewhere between 6 inches to

2.5 feet of sea-level rise in 2050 and

between 1 to 7 feet in 2100 (Table 3, CSAP

2015). There is strong scientific consensus

regarding sea-level trends, confirmed by

measurements from both a large network of tide gauges and satellite observations. Uncertainty regarding

the behavior of ice sheets as they interact with the sea, air and land accounts for the variation in

projections of future sea-level conditions globally and in Tampa Bay. The Tampa Bay Estuary Program

has modeled a number of plausible sea-level rise scenarios and shown that even with adaptation strategies

implemented throughout the region, total critical coastal habitat coverage is estimated to decline (Figure 4,

Sherwood and Greening 2014).

Table 3. Relative Sea Level Change Scenarios for St. Petersburg, Florida in Feet above Local Mean Sea Level (LMSL).

Figure 4. Estimated composition of critical coastal habitats in Tampa Bay and expected changes due to climate change and sea-level rise under a worst-case scenario (SLAMM 2 m SLR by 2100).

Figure 3. Mean Sea Level Trend (relative to Mean Lower Low Water) in

St. Petersburg, Florida, NOAA Tide Gauge #8726520

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Stressor: Increased air and water temperatures; Extended frost-free season

Likelihood: High

The Tampa Bay watershed has

experienced a trend of warming

temperatures across all seasons,

with annual mean temperatures

rising approximately 0.2°F per

decade. From 1939 to 2013,

annual high temperatures have

increased by approximately 0.1°F

per decade, with the most notable

increases occurring during fall

months. Average low temperatures

have risen at a greater rate, nearly

0.3°F per decade, signaling fewer

nighttime hours of cooling. Over

the period from 1981 to 2010, the

average mean temperature was

73.4°F, with the coldest month in

January (average 60.8°F) and the

warmest month in August

(83.2°F). Climate projections included in hazard analysis for the Tampa Bay area suggest more days of

extreme heat in the summer, with as many as 23 to 122 days above 95°F and 0 to 27 days above 100°F by

2100 (Figure 5). Extreme temperatures may also persist for longer sustained periods, with anywhere from

7 to 54 consecutive days of temperatures

95° or greater. Oceans play an important

role in regulating the Earth’s climate and

are able to absorb and release large

amounts of heat over long periods of

time. Global sea surface temperature

trends have been increasing (Figure 6)

and data suggest that the coastal waters

off of the Southeast U.S. will warm from

1.8°F to 7.2°F by the end of the century

(International Panel on Climate Change

2013).

Figure 5. Projected changes in summer and winter temperatures. From DHS Hazards Analysis for the Tampa Bay Area (2015).

Figure 6. Average global sea surface temperature, 1880-2015

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Stressor: Storminess

Likelihood: Moderate

Projected changes in the frequency and intensity of rainfall events or tropical storms may fall within

patterns of natural variability. Existing climate models are effective at projecting large-scale processes, but

patterns of precipitation in the Tampa Bay watershed are largely influenced by small-scale processes such

as sea-breezes and summertime convective activity that are not easily characterized by these models.

Tampa Bay Water continues to research appropriate methods to capture the influence of these processes

through statistical downscaling of global and national datasets and other methods, but has not developed

high confidence model projections for the region (Asefa & Adams 2013). In the Tampa Bay region, the

likelihood of rainfall and the potential for extreme rainfall events is greatest during the summer, with a one

percent chance of an 11 inch rainfall event occurring in any given year and a fifty percent chance of a 4

inch rainfall event occurring in any given year. Increases in the frequency of extreme precipitation events

in the southeastern U.S. have been observed but projections do not show reliable trends beyond the scope

of natural variability for the Tampa Bay watershed (Figure 7).

Figure 7. Projected changes in the frequency of days per year with “very heavy” or “extremely heavy” precipitation (DHS 2015).

Similarly, the intensity, frequency, and duration of hurricanes in the North Atlantic basin have increased

substantially since the early 1980s; however there is insufficient evidence to suggest that this change is a

result of anthropogenic causes, nor is it clear that this trend will persist as the climate continues to warm.

An improved understanding of likely rainfall patterns throughout the Tampa Bay watershed is important,

particularly for water quality, given that total nitrogen loads have been highly correlated with variations in

annual rainfall (Greening & Janicki 2006).

Stressor: Drought

Likelihood: Low

The southeastern U.S. and the Tampa Bay watershed are located in an area of transition between projected

wetter conditions in the northeast and drier conditions in the southwest. Projections regarding changes in

patterns of precipitation are highly uncertain and likely to fall within the range of natural variability.

Moreover, reliable information regarding projected rates of evapotranspiration is not available (NCA 2014,

DHS 2015).

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Stressor: Ocean acidification

Likelihood: Low/Moderate

Global ocean acidification trends have been documented extensively; however associated impacts on

marine ecosystems are not as clear. Scientific understanding of the effects of ocean acidification on marine

organisms, including shellfish and juvenile fishes, are primarily based upon laboratory and mesocosm

experiments and limited ocean observations. The biological response of individual organisms, populations,

and communities of species to gradual changes in pH is uncertain. In Tampa Bay, long-term water quality

monitoring data from the Environmental Protection Commission of Hillsborough County indicates that

seawater pH in Tampa Bay has steadily

risen in Tampa Bay since the 1980s,

contrary to global trends (Figure 8).

Local scientists have hypothesized that

the recovery of seagrass in Tampa Bay

has helped buffer against the chemical

impacts of ocean acidification, may

confer some resiliency to organisms

(particularly shellfish and other

economically important fish species)

that are particularly sensitive to ocean

acidification, and may serve as an

important, regional ocean acidification

refuge (Yates et al 2016). Several projects

are underway to examine this hypothesis,

including the installation of a high-resolution pH monitoring site within the bay, but more information is

necessary to understand the potential effects of this climate stressor.

Step 5: Risk Evaluation

Live polling was conducted using “Poll Everywhere,” a smart phone-based application, to collect information

regarding the perceived severity of previously identified climate risks. Stakeholders were asked to rate the

potential severity of each risk (low, moderate, high), considering spatial and temporal scales and general

qualitative consequence to the ecologic function of the bay. Stakeholders were instructed to rate the severity

as if the risk had already occurred and no intervening measures had been employed to mitigate their potential

effect. This information was subsequently synthesized with the risk analysis data into a series of matrices

(shown below) comparing the relative likelihood of occurrence and perceived severity of each risk, by CCMP

goal.

Figure 8. Seagrass acreage and pH trends in Tampa Bay.

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Discussion

The results of the vulnerability assessment suggest that increased temperatures (air and water) and sea level

rise are climate stressors of particular importance to the Tampa Bay watershed and may have adverse impacts

upon key TBEP goals pertaining to water and sediment quality, bay habitats, and fish and wildlife if

appropriate adaptation and mitigation strategies are not implemented. Notably, the TBEP’s marquee goals:

Maintaining nitrogen loading rates at adopted limits to provide water clarity sufficient to recover and maintain

at least 38,000 acres of seagrass baywide; Restoring the historic balance of coastal wetland habitats by

restoring 1,918 acres of salt marsh habitat and 840 acres of salt barren habitat over 2008 levels, and

preserving 15,139 acres of existing mangrove habitat; and Preserving the abundance and diversity of Tampa

Bay's fish and wildlife, are also likely to be the most vulnerable to the effects of a changing climate.

The results of the vulnerability assessment validate the CCMP’s current focus on understanding the effects of

sea-level rise on critical coastal habitats and addressing knowledge gaps regarding the potential effects of

ocean acidification within Tampa Bay. However, the vulnerability assessment also makes the need for further

research to improve projections for both rainfall and evapotranspiration rates clear. It should also be noted

that portions of this vulnerability assessment rely heavily upon perceptions of risk, which may not be the

most accurate way to compare different climate risks and vary greatly between individuals given their personal

biases pertaining to certainty and fear (Morrow 2009). Nevertheless, this vulnerability assessment provides a

framework for moving forward with an iterative process to ensure that the CCMP remains an effective,

resilient management tool that guides the protection and restoration of Tampa Bay.

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References

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Department of Homeland Security. 2015. Hazard Analysis for the Tampa Bay Area, Florida

Technical Support Document.

Greening, H.S. and A. Janicki. 2006. Toward Reversal of Eutrophic Conditions in a Subtropical Estuary:

Water Quality and Seagrass Response to Nitrogen Loading Reductions in Tampa Bay, FL. Environmental

Management, 38(2), 163-178. doi: 10.1007/s00267-005-0079-4.

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