Virginia Burkett is the Chief Scientist for Climate and Land Use Change at the U.S. Geological Survey. She was formerly Chief of the Forest Ecology Branch at the USGS National Wetlands Research Center in Lafayette, Louisiana. Margaret Davidson is the director of the NOAA Coastal Services Center and was previously executive director of the South Carolina Sea Grant Consortium.

Margaret Davidson, the director of the NOAA Coastal Services Center, is no stranger to the coast or its many challenges. Before joining NOAA, Margaret A. Davidson was executive director of the South Carolina Sea Grant Consortium from 1983 to 1995. She also served as special counsel and assistant attorney general for the Louisiana Department of Justice.

Coastal Impacts, Adaptation, and Vulnerabilities

A Technical Input to the 2013 National Climate Assessment

By Virginia Burkett, Margaret Davidson

ISLAND PRESS

Copyright © 2012 The National Oceanic and Atmospheric Administration
All rights reserved.
ISBN: 978-1-61091-433-8

Contents

Key Terms,
Acronyms,
Communicating Uncertainty,
Executive Summary,
CHAPTER 1: INTRODUCTION AND CONTEXT,
1.1 Scope and Purpose,
1.2 Linkages and Overlapping Topics of the NCA,
1.3 Reliance on the Coastal Zone,
CHAPTER 2: PHYSICAL CLIMATE FORCES,
2.1 Overview of Climate and Sea-level-rise Effects on Coasts,
2.2 Sea-level Rise and Future Scenarios,
2.3 Extreme Events and Future Scenarios,
2.4 Changes in Wave Regimes and Circulation Patterns,
2.5 Relative Vulnerability of Coasts,
2.6 Changes in Precipitation Patterns,
2.7 Temperature Change Impacts with a Focus on Alaska,
CHAPTER 3: VULNERABILITY AND IMPACTS ON NATURAL RESOURCES,
3.1 Multiple Stressors Interact at the Coast,
3.2 Biota, Habitats, and Coastal Landforms that Are Impacted by Complex Stressor Interactions and Subject to Nonlinear Changes and Tipping Points,
3.3 Conclusions,
CHAPTER 4: VULNERABILITY AND IMPACTS ON HUMAN DEVELOPMENT,
4.1 Overview of Impacts on Human Development and Societal Vulnerability,
4.2 Relative Vulnerability, Exposure, and Human Losses,
4.3 Socio-economic Impacts and Implications,
4.4 Human Health Impacts and Implications,
4.5 Implications for Coastal Military Installations and Readiness,
CHAPTER 5: ADAPTATION AND MITIGATION,
5.1 Adaptation Planning in the Coastal Zone,
5.2 Coastal Resource Management and Restoration in the Context of Climate Change,
5.3 Tools and Resources,
5.4 Coastal Mitigation Opportunities,
CHAPTER 6: INFORMATION GAPS AND SCIENCE NEEDED TO SUPPORT SUSTAINABLE COASTS,
6.1 Science Research Needs to Support Sustainable Coastal Management,
Appendix A: Chesapeake Bay Case Study,
Appendix B: Gulf of Mexico Case Study,
REFERENCES,

CHAPTER 1

Introduction and Context

Key Findings

• Changes in the environment associated with human development activities compromise the ability of the coasts to continue to provide a multitude of benefits including food, clean water, jobs, recreation, and protection from storms. In some cases, these benefits are further impacted by the changing climate. High Confidence.

• Adapting to the changing climate will be a challenge for coastal economies that contributed $8.3 trillion to the GDP in 2010 and depend on coastal landforms, water resources, estuaries, and other natural resources to sustain them. High Confidence.

• Coastal states and communities will need strategies to enable them to manage current stressors and the confounding impacts of a changing climate to conserve, protect, and restore coastal habitats. Easing the existing pressures on coastal environments to improve their resiliency is one method of coping with the adverse effects of climate change. High Confidence.

1.1 Scope and Purpose

Impacts on coastal systems are among the most costly and most certain consequences of a warming climate (Nicholls et al., 2007). The warming atmosphere is expected to accelerate sea-level rise as a result of the decline of glaciers and ice sheets and the thermal expansion of sea water. As mean sea level rises, coastal shorelines will retreat and low-lying areas will tend to be inundated more frequently, if not permanently, by the advancing sea. As atmospheric temperature increases and rainfall patterns change, soil moisture and runoff to the coast are likely to be altered. An increase in the intensity of climatic extremes such as storms and heat spells, coupled with other impacts of climate change and the effects of human development, could affect the sustainability of many existing coastal communities and natural resources. This report examines the known effects and relationships of these and other climate change variables on coasts of the U.S. It also describes how several major sectors of the U.S. economy are likely to be affected as well as the diversity of adaptation options that are either being considered or already implemented in coastal regions.

This report is one of a series of technical inputs for the third NCA conducted under the auspices of the U.S. Global Change Research Program. The U.S. Global Change Research Act of 1990 requires that periodic national climate assessments be conducted and submitted to the President and the Congress. Each assessment acts as a national snapshot or status report on climate change science and impacts. Two previous national assessment reports, each containing a brief chapter on coastal impacts, were published in 2000 and 2009.

The primary purpose of this report is to provide a technical foundation for the coastal chapter of the third NCA. The third U.S. assessment report is intended for use by communities and the nation as a whole to create sustainable and environmentally sound development paths. It will also provide a basis for prioritizing federal climate science investments and for identifying the most likely hotspots of societal vulnerability during the coming decades.

This assessment of coastal impacts, adaptation, and vulnerability in coastal regions of the United States begins with a characterization of the economic, cultural, and ecological significance of the coastal zone. This first chapter also summarizes how this report links with other topics covered in the third NCA. Chapter 2 provides an overview of the physical drivers of change in coastal ecosystems. Chapters 3 and 4 describe the observed and projected impacts on natural coastal ecosystems and coastal communities, respectively. Chapter 5 addresses the societal adaptation and mitigation responses to climate change in the coastal zone. The last chapter of this report addresses the science needs of coastal decision makers as they begin to prepare for and adapt to climate change.

1.2 Linkages and Overlapping Topics of the NCA

A total of 35 U.S. states, commonwealths, and territories have coastlines that border the oceans or Great Lakes. This assessment is intended to broadly characterize climate impacts, adaptation, and vulnerabilities for U.S. coastal regions. Due to the geography of the U.S. coastline and the importance of the coast to the U.S. economy, this synthesis relating to coastal systems intersects with many other sectoral and regional assessment activities that are being conducted to support the NCA. Examples of these intersecting assessment activities include: • Regional Assessments. All eight regions of the NCA have coastal areas, whether on the Atlantic, Gulf of Mexico, Pacific Islands, or Great Lakes shores. Regional assessment reports will address impacts such as changing water levels, storm intensities, and precipitation more specifically, providing localized information using the available downscaled data, models, and regional scenarios developed for that area.

• Great Lakes. A separate report on the potential impacts of climate change on the Great Lakes region has been prepared, and some impacts on the U.S coasts of the lakes are discussed in this document.

• Water Resources. A variety of challenges to managing water supply and waste-water treatment will be encountered by water resource managers as they face changes in precipitation patterns and sea-level rise. Changes in the timing and supply of freshwater to coastal aquifers and through surface waters and salt-water intrusion into the system could impact water management infrastructure and water supplies for residential, commercial, and industrial uses, as well asirrigation for agriculture. Rising sea levels and increased storm intensity could impact water control structures such as levees and dams in the coastal zone.

• Agriculture. The impacts of climate change on agriculture may be intensified in low-lying coastal areas. Saltwater intrusion may render some lands inappropriate for farming. Stronger storms and increased precipitation or drought may lead to major changes in planting patterns and types of crops grown.

• Forestry. In coastal areas, forests may be affected by many of the same factors as agriculture, but increased severity of storms may have a greater impact on forests due to the longer cycle from planting to harvest. Loss of standing timber due to high winds may also have long term economic impacts. Saltwater encroachment and more frequent saturation of coastal forest soils may affect the potential for forest regeneration and other silvicultural practices.

• Public Health. Climate-related impacts on health and well-being include impacts on food supply, disease transmission, and environmental health. An increase is expected in contamination of coastal fishing and recreational waters in areas with high runoff and stressed sanitation systems; changes in access to and quality of food from the sea; and northward shifts in habitat. Vector-borne diseases may also be intensified in coastal areas as temperature and rainfall patterns change. Higher concentrations of populations in coastal areas may intensify the impacts of increased heat and humidity in coastal areas.

• Transportation. Increased flooding and inundation of roads and bridges in coastal areas may impede emergency preparation for and response to coastal storms, delay ground and other transportation, or alter traffic patterns. Improvements to maritime transportation infrastructure to respond to climate change may be a complex mix of public and private investment because most freight facilities are privately owned. Maintaining effective transportation through ports is of special concern due to their significant impact on the national economy.

• Energy Supply. Most saltwater consumption in U.S. coastal counties occurs during thermoelectric power generation. Changes in water temperature may reduce the effectiveness of water as a cooling medium. The coasts are areas of exploration for energy sources including traditional sources, such as the extraction and transportation of offshore oil to inland areas, and alternative sources, such as tidal, wave, and wind energy.

• Ecosystems and Biodiversity. The ecosystems and biodiversity report of the NCA will examine the impacts of rising sea levels and other changing climatic factors on land cover and ecosystems. Temperature and changes in the hydrologic cycle are likely to have significant effects on both coastal ecosystems and biodiversity. On the coast, wetlands and the associated species will face pressure from changes in salinity, inundation, and erosion. As coastal areas continue to develop, less upland area will be available for wetland restoration or migration due to the presence of hardened shorelines.

• Urban Infrastructure and Vulnerability. Most of the U.S. population lives with coastal watersheds and a significant portion of the nation’s infrastructure is at risk due to increased inundation and erosion from storms and sea-level rise.

• Marine. Identifying a firm boundary between coastal and marine issues associated with climate change is difficult. Sediments, water, and nutrients move across the coastal and marine systems affecting water quality conditions and habitats in both realms. Many intersections exist between the marine chapter and the coastal chapter because of the intersections between geography and resources. For example, estuaries and coastal marshes provide critical nursery habitats for many marine species.

1.3 Reliance on the Coastal Zone

The coast has long been an area that has provided communities with a multitude of benefits: food, clean water, jobs, recreation, and protection from hurricanes. Coasts provide natural harbors for commerce, trade, and transportation; beaches and shorelines that attract residents and tourists; and wetlands and estuaries that are critical for sustained fisheries. Healthy coastal ecosystems cycle and move nutrients, store carbon, detoxify wastes, and purify air and water. Coastal ecosystems help to mitigate floods and serve as buffers from coastal storms that bring high winds and salt water inland and erode the shore. Coastal regions have also been critical in the development, transportation, and processing of oil and natural gas resources and, more recently, have been explored as a source of energy captured from wind and waves. Over 56 percent of our nation’s total energy production occurred in coastal states in 2009 (NOAA, 2011a). The ability of coasts to provide this suite of ecosystem services is being compromised by environmental alterations associated with human development activities and, in some cases, further impacted by the changing climate.

Increasing Population and Changing Land Use

Employment, recreation, and tourism, water-based commerce, and energy and mineral production are driving forces of population migration to coastal areas (Bookman et al., 1999; H. John Heinz Center, 2000; U.S. Commission on Ocean Policy, 2004). In 2010, 164 million people, a little more than 50 percent of the nation’s total population, resided within the coastal watershed counties of the U.S. and territories, including the Great Lakes (Figure 1-1). From 1970 to 2010, U.S. population in these coastal watershed counties increased by 45 percent, or 50.9 million people (NOAA, 2011b). These population estimates do not include the large number of seasonal visitors to coastal areas that benefit from and place demands on natural resources. Examples of these areas include Florida, Southern California, Maine, and North Carolina that host a large number of seasonal homes (Crossett et al., 2004).

The fraction of the U.S. population living in coastal counties is expected to increase by 144 percent, or 131.2 million people, by the year 2100, according to EPA (2010) based on a population model consistent with the A2 scenario of the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC SRES) and by 50 percent, or 46.2 million people, using assumptions consistent IPCC SRES scenario B1 (Nakicenovic et al., 2000; U.S. EPA, 2010). Because the nation’s coastal watershed counties, excluding Alaska, represent only 17 percent of total U.S. land area (NOAA, 2011b), population densities are expected to be higher in these areas than in other parts of the country.

Concomitant with increasing populations, land use patterns have changed along the coast. Many agricultural and previously undeveloped areas have been converted into low-density residential, commercial, and industrial uses (Beach, 2002). Consequent sprawl and urbanization has affected coastal ecosystems in a variety of ways. Alterations to land use and natural inlets impact nutrient runoff, stormwater management, and water quality; shoreline hardening and dredging alters coastal circulation patterns exacerbating shoreline erosion and the ability to attenuate flooding; and development that alters land cover impairs habitats for native species. Coastal storms interact with changing land uses and land cover, particularly in terms of coastal flooding that puts people and property at risk.

The EPA developed a methodology for quantifying relationships between population, housing density, percent of impervious surfaces, and water quality impairment (EPA, 2009). If present relationships are maintained in the future, the increase in population through the end of this century, under the A2 emissions scenario, will contribute to 37 and, under the B1 emissions scenario, 11 additional coastal watersheds with a land surface of 10 percent or more total impervious surface cover, a threshold at which water quality and aquatic communities are likely to be impaired, though substantially lower thresholds have been shown (Angradi et al., 2010; Cuffney et al., 2010; King et al., 2011). Although the extent and permeability of impervious surfaces can be mitigated through a variety of strategies (Dietz, 2007) increased residential housing and commercial and industrial development are expected to continue to result in land and resource uses that degrade ecosystem services (Schlacher et al., 2011).

Changing Coastal Economy

The nation’s economy is highly dependent on the coasts. Fifty-eight percent of our nation’s Gross Domestic Product (GDP), valued at $8.3 trillion, is generated in the coastal watershed counties along the oceans and Great Lakes (NOAA, 2011c). If the nation’s coastal watershed counties were considered an individual country, they would rank number two in GDP globally, only behind the U.S. as a whole (NOAA, 2011c). Economic activity in U.S. coastal watershed counties accounts for approximately 66 million jobs and $3.4 trillion in wages (NOAA, 2011c) through a diversity of industries and commerce. Over $1.9 trillion in imports came through U.S. ports in 2010, and these commercial ports directly supported over 13 million jobs (NOAA, 2011f).

Traditionally the U.S. coastal economy was dominated by manufacturing, but service industries are now the primary contributors (Kildow et al., 2009). Urban areas, where more than 9 in 10 residents and jobs are located, are the economic centers of the coast (Kildow et al., 2009). In 2007, coastal counties were more specialized than the U.S. as a whole in four major economic sectors: professional and business services, information services, financial activities including real estate, and other services (Kildow et al., 2009). In addition, shore-adjacent counties show greater specialization in the leisure and hospitality service sector, reflecting the importance of coasts for tourism and recreation. Every coastal state hosts more than one million coastal visitors each year (Pendleton, 2008).

Our nation’s ocean and Great Lakes coasts are important centers for commercial and recreational fishing. The U.S. seafood industry includes the commercial harvest sector, seafood processors and dealers, seafood wholesalers and distributors, importers, and seafood retailers. In 2009, this industry supported approximately 1 million full- and part-time jobs and generated $116 billion in sales impacts, $32 billion in income impacts, and $48 billion in value added impacts (NOAA, 2011d). Recreational fishing also plays a large part in the economy, which contributed $50 billion in sales impacts to the U.S. economy, generated $23 billion in value added impacts, and supported over 327,000 jobs in 2009 (NOAA, 2011e).

The anticipated growth in coastal population alone is likely to increase the demand on resources that are critical to coastal economies. The next thirty years could bring the largest shift in the ocean and coastal economies since the arrival of industrialization and rapid urbanization in the late 19th century (Kildow et al., 2009).

(Continues…)Excerpted from Coastal Impacts, Adaptation, and Vulnerabilities by Virginia Burkett, Margaret Davidson. Copyright © 2012 The National Oceanic and Atmospheric Administration. Excerpted by permission of ISLAND PRESS.
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