🌊Coastal Resilience Engineering Unit 2 – Coastal Climate Change Impacts

Key Concepts and Definitions

• Climate change refers to long-term shifts in global or regional climate patterns, primarily due to increased levels of atmospheric carbon dioxide produced by the use of fossil fuels
• Sea level rise (SLR) is the increase in the level of the world's oceans due to the effects of climate change, such as thermal expansion caused by warming of the ocean and increased melting of land-based ice (glaciers and ice sheets)
• Coastal erosion is the loss or displacement of land along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms
  • Coastal erosion can be exacerbated by human activities (coastal development, sand mining) and natural processes (sea level rise, more frequent and intense storms)
• Coastal flooding occurs when normally dry, low-lying land is inundated by seawater, often due to extreme tidal events, storm surges, or sea level rise
• Saltwater intrusion is the movement of saline water into freshwater aquifers, which can lead to contamination of drinking water sources and other consequences for human and ecological communities
• Coastal ecosystems, such as wetlands, mangroves, and coral reefs, provide critical habitats for diverse species and offer important ecosystem services (coastal protection, carbon sequestration, water filtration)
• Coastal resilience refers to the ability of a coastal system, including its socioeconomic and ecological components, to withstand, recover from, and adapt to the impacts of climate change and other stressors

Coastal Climate Change Drivers

• Greenhouse gas emissions, primarily from human activities like burning fossil fuels and deforestation, trap heat in the atmosphere and contribute to global warming
• Rising global temperatures lead to thermal expansion of the oceans, as water expands when it warms, contributing to sea level rise
• Melting of land-based ice, such as glaciers and ice sheets (Greenland and Antarctic), due to increasing temperatures adds significant volumes of water to the oceans, further driving sea level rise
  • Melting of sea ice (Arctic) does not directly contribute to sea level rise, as this ice is already displacing its own weight in the water
• Changes in precipitation patterns, including more frequent and intense rainfall events, can lead to increased coastal flooding and erosion
• More frequent and intense extreme weather events, such as hurricanes, typhoons, and storm surges, can cause severe damage to coastal infrastructure and ecosystems
• Ocean acidification, caused by the absorption of excess atmospheric carbon dioxide, can have detrimental effects on marine organisms (shellfish, coral reefs) and the ecosystems they support
• Shifts in ocean currents and circulation patterns, influenced by changes in temperature and salinity, can affect the distribution of marine species and alter coastal processes

Physical Impacts on Coastal Environments

• Sea level rise leads to increased coastal flooding, particularly during high tides, storm surges, and extreme weather events
• Coastal erosion is accelerated by rising sea levels, changes in wave patterns, and more frequent and intense storms, leading to shoreline retreat and loss of land
• Saltwater intrusion into freshwater aquifers and surface waters can occur as sea levels rise, contaminating drinking water sources and affecting agricultural activities
  • Saltwater intrusion can also alter soil chemistry, impacting coastal vegetation and ecosystems
• Changes in sediment transport and deposition patterns, influenced by altered wave and current dynamics, can affect the stability and morphology of coastlines (beaches, dunes, estuaries)
• Increased frequency and severity of extreme weather events can cause damage to coastal infrastructure (buildings, roads, bridges) and disrupt essential services
• Rising water tables, due to sea level rise and changes in precipitation, can lead to groundwater flooding and reduced drainage capacity in low-lying coastal areas
• Ocean acidification can impair the growth and survival of calcifying organisms (oysters, clams, coral reefs), leading to changes in coastal ecosystem structure and function
• Thermal stress, caused by rising ocean temperatures, can lead to coral bleaching events and the degradation of coral reef ecosystems, which provide critical habitats and coastal protection

Ecological and Biodiversity Effects

• Coastal habitat loss and degradation, due to sea level rise, erosion, and other climate change impacts, can lead to declines in biodiversity and ecosystem functioning
  • Wetlands, mangroves, and seagrass beds are particularly vulnerable to sea level rise and may struggle to keep pace with rising water levels
• Shifts in species distribution and abundance can occur as organisms respond to changing environmental conditions (temperature, salinity, pH) and habitat availability
  • Some species may migrate to higher latitudes or elevations seeking more suitable conditions, while others may face local extinctions
• Disruption of ecological interactions and food webs can result from changes in species composition, phenology (timing of life cycle events), and behavior
• Increased spread of invasive species, which may be better adapted to changing conditions, can outcompete native species and alter ecosystem dynamics
• Reduced ecosystem resilience and adaptive capacity, as multiple stressors (climate change, pollution, overfishing) interact and compound their effects on coastal ecosystems
• Changes in primary productivity and carbon sequestration, as rising temperatures, ocean acidification, and other factors influence the growth and survival of phytoplankton, algae, and other primary producers
• Potential loss of ecosystem services, such as coastal protection, nutrient cycling, and fisheries production, as coastal ecosystems become degraded or transformed
• Increased vulnerability of rare, threatened, and endangered species, which may have limited ability to adapt to rapid environmental changes or shift their ranges

Socioeconomic Consequences

• Damage to coastal infrastructure, including buildings, roads, ports, and energy facilities, can result in significant economic losses and disruption of essential services
• Displacement of coastal communities, particularly in low-lying and densely populated areas, as rising sea levels and increased flooding render some areas uninhabitable
  • Climate-induced migration can lead to social, cultural, and political challenges in both origin and destination communities
• Impacts on coastal tourism and recreation, as beach erosion, coral reef degradation, and other changes affect the attractiveness and accessibility of coastal destinations
• Reduced agricultural productivity in coastal regions, due to saltwater intrusion, flooding, and changes in temperature and precipitation patterns
• Increased costs associated with coastal protection, adaptation, and disaster recovery, placing financial burdens on governments, businesses, and individuals
• Potential disruption of global trade and supply chains, as climate change impacts affect the reliability and efficiency of coastal transportation networks (ports, shipping routes)
• Exacerbation of existing socioeconomic inequalities, as vulnerable communities (low-income, indigenous) may have fewer resources to cope with and adapt to climate change impacts
• Increased public health risks, such as waterborne diseases, heat stress, and mental health challenges, associated with flooding, displacement, and other climate-related stressors

Vulnerability Assessment Methods

• Coastal vulnerability indices (CVI) integrate multiple physical, ecological, and socioeconomic variables (elevation, geology, wave exposure, population density) to assess the relative vulnerability of different coastal segments
• Geospatial analysis and mapping tools (GIS, remote sensing) are used to visualize and analyze spatial patterns of coastal vulnerability, exposure, and risk
  • These tools can help identify hotspots of vulnerability and prioritize areas for adaptation interventions
• Scenario-based modeling approaches simulate potential future conditions under different climate change and socioeconomic scenarios to assess the range of possible impacts and inform decision-making
• Participatory vulnerability assessments engage local communities and stakeholders in identifying and prioritizing climate change risks, impacts, and adaptation options
  • These assessments can incorporate local knowledge, values, and perceptions to ensure that adaptation strategies are socially and culturally appropriate
• Indicator-based approaches use a set of quantitative or qualitative indicators (sea level rise, coastal erosion rates, population at risk) to measure and track changes in coastal vulnerability over time
• Risk assessment frameworks consider the likelihood and consequences of different climate change impacts to prioritize risks and guide adaptation planning
• Economic valuation methods, such as cost-benefit analysis and ecosystem service valuation, are used to assess the potential economic impacts of climate change and the benefits of adaptation measures
• Multi-criteria decision analysis (MCDA) is a structured approach for evaluating and prioritizing adaptation options based on multiple criteria (effectiveness, cost, feasibility, social acceptance)

Adaptation Strategies and Solutions

• Coastal protection measures, such as seawalls, dikes, and revetments, can help defend against sea level rise, flooding, and erosion, but may have unintended ecological consequences
• Nature-based solutions, such as beach nourishment, dune restoration, and living shorelines, work with natural processes to enhance coastal resilience while providing co-benefits for biodiversity and ecosystem services
  • Green infrastructure (wetlands, mangroves, oyster reefs) can dissipate wave energy, trap sediments, and provide valuable habitats
• Managed retreat or planned relocation involves moving people, infrastructure, and activities away from high-risk coastal areas to minimize exposure to climate change impacts
• Adaptation of coastal infrastructure, such as elevating buildings, retrofitting drainage systems, and designing flood-resistant structures, can reduce vulnerability to sea level rise and extreme weather events
• Coastal zoning and land-use planning can guide development away from high-risk areas and promote sustainable coastal management practices
• Early warning systems and emergency response plans can help communities prepare for and respond to coastal hazards, such as storm surges and flooding
• Ecosystem-based adaptation focuses on conserving, restoring, and sustainably managing coastal ecosystems to enhance their natural resilience and the ecosystem services they provide
• Capacity building and education initiatives can raise awareness about climate change impacts, promote behavior change, and build local capacity for adaptation planning and implementation

Case Studies and Real-World Examples

• The Netherlands' Delta Works is a series of dams, sluices, locks, dikes, and storm surge barriers designed to protect the low-lying country from coastal flooding and sea level rise
  • This innovative system of coastal defenses showcases the importance of long-term planning and investment in adaptation infrastructure
• The Maldives, a low-lying island nation in the Indian Ocean, is implementing a range of adaptation measures to address sea level rise and coastal erosion, including beach nourishment, coral reef conservation, and coastal vegetation planting
• In the United States, the Louisiana Coastal Master Plan outlines a comprehensive strategy for restoring and protecting the state's rapidly eroding coastline, using a combination of structural (levees, floodgates) and nature-based (wetland restoration, sediment diversion) approaches
• The Seychelles is promoting ecosystem-based adaptation by establishing marine protected areas, restoring coral reefs, and engaging local communities in sustainable coastal resource management
  • These efforts aim to enhance coastal resilience while supporting the country's tourism-dependent economy
• In Bangladesh, the Coastal Embankment Improvement Project is working to upgrade and rehabilitate the country's extensive network of coastal embankments, which protect millions of people from tidal flooding and storm surges
• The City of Miami Beach, Florida, is investing in a range of adaptation measures, including elevating streets and installing pumps to manage sea level rise and flooding, as well as encouraging green infrastructure and resilient building design
• The Pacific Island nation of Kiribati is exploring options for planned relocation and "migration with dignity" as a long-term adaptation strategy, recognizing the existential threat posed by sea level rise to its low-lying atolls
• In Australia, the Great Barrier Reef Marine Park Authority is implementing a comprehensive Climate Change Adaptation Strategy to build the resilience of the world's largest coral reef system in the face of warming temperatures, ocean acidification, and other stressors