Glossary

are a critical aspect of Coastal Resilience Engineering. Historical records, including and geological evidence, provide insights into past sea levels, while offers precise modern measurements. Understanding these trends is crucial for predicting future coastal changes and developing .

Sea level rise results from complex interactions between oceans, atmosphere, and ice. of oceans and melting land-based ice are major contributors. Regional variations, caused by factors like and , complicate the global picture. This knowledge is essential for effective coastal management and engineering solutions.

Historical sea level records

  • Sea level records provide crucial insights into past climate conditions and help predict future coastal changes in Coastal Resilience Engineering
  • Understanding historical sea level trends informs adaptation strategies for coastal communities and
  • Combining multiple data sources enhances the accuracy and reliability of long-term sea level reconstructions

Tide gauge measurements

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  • Continuous sea level observations recorded by mechanical float gauges since the 18th century
  • Network of tide gauges globally measures local sea level changes relative to a fixed point on land
  • Longest tide gauge record from Amsterdam dates back to 1700
  • Challenges include accounting for vertical land movements and uneven global distribution of gauges

Geological evidence

  • Provides sea level data over much longer timescales (thousands to millions of years)
  • Includes analysis of coral reefs, marine terraces, and sediment cores
  • Microfossils (foraminifera) in sediment cores indicate past sea levels and environmental conditions
  • Reconstructs sea level history during past warm periods (interglacials) for comparison with current trends

Satellite altimetry data

  • Space-based measurements of global sea surface height since 1992
  • Satellites (TOPEX/Poseidon, Jason series) use radar to measure distance between satellite and sea surface
  • Provides near-global coverage and high-precision measurements (accuracy of a few centimeters)
  • Allows detection of regional variations and short-term fluctuations in sea level

Causes of global sea level rise

  • Global sea level rise results from complex interactions between ocean, atmosphere, and cryosphere systems
  • Understanding these causes is essential for accurate projections and effective coastal management strategies
  • Coastal Resilience Engineering must account for multiple contributing factors to develop comprehensive adaptation plans

Thermal expansion of oceans

  • Occurs as seawater warms and increases in volume
  • Responsible for about 30-50% of observed global sea level rise since 1971
  • Rate of thermal expansion varies with depth and location in the ocean
  • Deeper, colder waters expand more than surface waters for the same temperature increase

Melting of land-based ice

  • Contributes freshwater to the oceans, raising global sea level
  • Major sources include glaciers, ice caps, and ice sheets (Greenland and Antarctica)
  • Greenland Ice Sheet loss has accelerated, contributing about 0.7 mm/year to sea level rise
  • Antarctic Ice Sheet contribution remains uncertain but potentially significant for future sea level rise

Groundwater extraction vs storage

  • Groundwater depletion adds water to the oceans, raising sea level
  • Estimated contribution of 0.3-0.4 mm/year to global sea level rise
  • Counteracted by increased water storage in artificial reservoirs and dams
  • Net effect on sea level depends on balance between extraction and storage over time

Regional variations in sea level

  • Sea level changes are not uniform globally, with significant regional differences
  • Understanding regional variations crucial for local coastal management and adaptation planning
  • Coastal Resilience Engineering must consider site-specific sea level trends for effective design and implementation

Vertical land movements

  • Caused by geological processes (tectonics, isostatic rebound) and human activities (subsidence)
  • Post-glacial rebound raises land in formerly glaciated regions (Scandinavia, Canada)
  • Subsidence in delta regions due to sediment compaction and
  • Can amplify or reduce relative sea level rise at local scales

Ocean circulation patterns

  • Influence regional sea level through redistribution of heat and mass
  • Changes in major currents (Gulf Stream, Antarctic Circumpolar Current) affect local sea levels
  • El Niño-Southern Oscillation (ENSO) causes temporary sea level variations in the Pacific
  • Long-term changes in ocean circulation can lead to persistent regional sea level anomalies

Gravitational effects

  • Redistribution of mass from melting ice sheets alters Earth's gravitational field
  • Leads to lower sea level rise near melting ice sheets and higher rise in distant locations
  • Greenland ice loss causes sea level to fall nearby but rise more in the Southern Hemisphere
  • Complicates global sea level projections and requires consideration in regional assessments
  • Monitoring global sea level trends essential for understanding on coastal systems
  • Observed trends inform policy decisions and adaptation strategies in Coastal Resilience Engineering
  • Combining multiple data sources provides a comprehensive picture of past and present sea level changes

20th century rates

  • Average rate of global sea level rise during the 20th century estimated at 1.7 mm/year
  • Acceleration observed in the latter half of the century
  • Tide gauge records show significant spatial and temporal variability
  • Reconstruction methods combine tide gauge data with proxy records to estimate global trends

Recent acceleration

  • Satellite altimetry reveals global mean sea level rise of 3.3 mm/year since 1993
  • Acceleration detected in the altimetry record, with rates increasing to 4.5 mm/year in recent years
  • Increased contributions from ice sheet melting and thermal expansion drive acceleration
  • Observed acceleration consistent with projections from climate models

Projections for 21st century

  • IPCC projects global mean sea level rise of 0.43-0.84 m by 2100 under intermediate emissions scenario
  • High-end scenarios suggest potential rise exceeding 1 m by 2100
  • Long-term projections indicate continued sea level rise for centuries due to thermal inertia of oceans
  • Uncertainties in future emissions and ice sheet dynamics affect projection accuracy

Impacts on coastal systems

  • Sea level rise poses significant challenges to coastal environments and human settlements
  • Coastal Resilience Engineering focuses on mitigating these impacts through adaptive strategies
  • Understanding and quantifying impacts essential for effective coastal management and planning

Coastal erosion and flooding

  • Increased wave energy and storm surge heights exacerbate
  • Low-lying areas face more frequent and severe flooding events
  • Shoreline retreat threatens coastal infrastructure and habitats
  • Adaptation measures include beach nourishment, , and

Saltwater intrusion

  • Rising sea levels push saltwater further inland in coastal aquifers and estuaries
  • Threatens freshwater resources for drinking water and agriculture
  • Alters soil chemistry and impacts coastal vegetation
  • Mitigation strategies include improved water management and desalination technologies

Ecosystem changes

  • Inundation of coastal wetlands and mangroves leads to habitat loss
  • Shifts in species distribution and composition of coastal ecosystems
  • Coral reefs face increased stress from sea level rise combined with ocean warming and acidification
  • (living shorelines) can enhance ecosystem resilience to sea level rise

Measurement techniques and technologies

  • Accurate and precise measurements crucial for understanding sea level changes
  • Advances in technology improve spatial and temporal resolution of sea level data
  • Integration of multiple measurement techniques enhances overall understanding of sea level dynamics

Tide gauges vs satellite altimetry

  • Tide gauges provide long-term local records but limited spatial coverage
  • Satellite altimetry offers near-global coverage but shorter time series
  • Combining both methods allows for cross-validation and improved accuracy
  • Tide gauges essential for calibrating satellite measurements and studying local effects

GPS and geodetic observations

  • GPS measurements track vertical land movements at tide gauge locations
  • Improves accuracy of relative sea level trends derived from tide gauges
  • Geodetic techniques (VLBI, SLR) provide reference frame for satellite altimetry
  • Continuous GPS networks monitor regional land deformation patterns

Gravimetry for mass changes

  • GRACE satellite mission measures changes in Earth's gravity field
  • Allows estimation of ocean mass changes contributing to sea level rise
  • Distinguishes between steric (thermal expansion) and mass-related sea level changes
  • Provides insights into ice sheet mass balance and terrestrial water storage variations

Uncertainties and challenges

  • Addressing uncertainties crucial for improving sea level projections and risk assessments
  • Challenges in sea level science inform research priorities and data collection strategies
  • Understanding limitations essential for effective communication of sea level risks to stakeholders

Data quality and coverage

  • Historical tide gauge records have varying quality and may contain gaps
  • Uneven global distribution of tide gauges limits understanding of regional variations
  • Satellite altimetry faces challenges in coastal areas and high latitudes
  • Efforts to digitize historical records and expand monitoring networks ongoing
  • Interannual to decadal climate oscillations (ENSO, PDO) influence sea level
  • Distinguishing natural variability from anthropogenic trends requires long time series
  • Statistical methods (empirical mode decomposition) help separate different timescales
  • Understanding natural variability crucial for detecting acceleration in sea level rise

Model limitations

  • Climate models struggle to accurately represent all processes affecting sea level
  • Ice sheet dynamics and ocean-ice interactions not fully captured in current models
  • Uncertainties in future emissions scenarios affect long-term projections
  • Ensemble approaches and model intercomparison projects address model limitations

Future scenarios and projections

  • Projecting future sea level rise essential for long-term coastal planning and adaptation
  • Multiple scenarios consider different emissions pathways and socioeconomic developments
  • Coastal Resilience Engineering must account for range of possible future sea level scenarios

IPCC projections

  • Latest IPCC report (AR6) provides updated sea level projections
  • Likely range of global mean sea level rise by 2100 spans 0.28-1.01 m across scenarios
  • Projections include contributions from thermal expansion, glaciers, and ice sheets
  • Low-likelihood, high-impact scenarios explore potential for larger rises (up to 2 m by 2100)

Emission scenarios

  • Representative Concentration Pathways (RCPs) and Shared Socioeconomic Pathways (SSPs) used
  • Range from low-emission (RCP2.6, SSP1-2.6) to high-emission (RCP8.5, SSP5-8.5) scenarios
  • Sea level projections vary significantly depending on future greenhouse gas emissions
  • Mitigation efforts to reduce emissions can substantially lower long-term sea level rise

Tipping points and thresholds

  • Potential for abrupt changes in ice sheet dynamics could lead to rapid sea level rise
  • Marine ice sheet instability in West Antarctica represents major tipping point
  • Greenland Ice Sheet may have threshold temperature for irreversible melting
  • Deep uncertainty surrounds timing and magnitude of potential tipping points

Implications for coastal management

  • Sea level rise poses significant challenges for coastal communities and infrastructure
  • Coastal Resilience Engineering plays crucial role in developing adaptive management strategies
  • Integration of sea level projections into planning and policy essential for long-term resilience

Adaptation strategies

  • Range from protection (seawalls, levees) to accommodation (elevated structures) to retreat
  • Nature-based solutions (mangrove restoration, living shorelines) gain increasing attention
  • Adaptive pathways approach allows flexibility in response to changing sea level conditions
  • Cost-benefit analysis helps prioritize adaptation measures based on local context

Infrastructure planning

  • Long-lived coastal infrastructure must account for future sea level rise
  • Design standards and building codes updated to incorporate sea level projections
  • Critical facilities (ports, power plants) require special consideration for resilience
  • Green infrastructure approaches complement traditional engineering solutions

Policy and decision-making

  • Integration of sea level rise into coastal zone management policies
  • Development of risk-based frameworks for assessing and managing coastal hazards
  • Challenges in addressing deep uncertainty in long-term sea level projections
  • Need for improved communication of sea level risks to policymakers and public

Sea level rise in climate models

  • Climate models crucial tools for understanding and projecting future sea level changes
  • Continuous improvement in model resolution and process representation
  • Integration of sea level components enhances overall climate system understanding

Coupled climate-ice sheet models

  • Incorporate dynamic ice sheet models into global climate models
  • Improve representation of ice-ocean interactions and ice sheet mass balance
  • Allow for feedbacks between climate change and ice sheet evolution
  • Enhance ability to project long-term sea level rise under different scenarios

Model validation and improvement

  • Comparison of model outputs with observational data (tide gauges, satellites)
  • Paleoclimate simulations test model performance under different climate states
  • Ongoing efforts to improve representation of key processes (ice shelf melting, ocean eddies)
  • Development of high-resolution regional models for better coastal projections

Ensemble projections

  • Multiple model runs with varying initial conditions and parameters
  • Provide range of possible outcomes and quantify uncertainties
  • Multi-model ensembles (CMIP6) combine results from different climate models
  • Probabilistic projections inform risk assessment and adaptation planning in coastal areas

Key Terms to Review (30)

Adaptation Strategies: Adaptation strategies refer to the approaches and methods implemented to adjust and respond to the impacts of environmental changes, particularly those related to climate change. These strategies aim to minimize vulnerability and enhance resilience in communities facing challenges like rising sea levels, coastal erosion, and extreme weather events. By focusing on practical solutions, adaptation strategies are essential for managing risks associated with various hazards linked to changing environmental conditions.
Climate adaptation plans: Climate adaptation plans are strategic frameworks designed to prepare and respond to the impacts of climate change on communities, ecosystems, and economies. These plans often involve assessing vulnerabilities, identifying necessary actions, and implementing measures to enhance resilience against climate-related risks such as rising sea levels, extreme weather events, and changing ecosystems.
Climate change impacts: Climate change impacts refer to the various effects that climate change has on natural and human systems, including alterations in weather patterns, rising sea levels, and disruptions to ecosystems. These impacts can lead to significant challenges such as habitat loss, increased flooding, and threats to cultural heritage sites. Understanding these impacts is crucial for developing effective strategies for resilience and adaptation in coastal environments.
Coastal Erosion: Coastal erosion is the process by which coastlines are eroded and reshaped by the action of waves, currents, tides, and human activity. This natural process is influenced by various factors, including sediment transport and sea level changes, which can significantly impact coastal landforms and ecosystems.
Displacement risk: Displacement risk refers to the potential for individuals or communities to be forced to leave their homes due to environmental factors, particularly those associated with climate change such as rising sea levels, extreme weather events, and habitat loss. This risk is directly tied to global sea level trends, as coastal areas are increasingly vulnerable to inundation and erosion, leading to significant social, economic, and cultural implications for affected populations.
Ecosystem changes: Ecosystem changes refer to alterations in the structure, composition, and functioning of ecosystems due to natural processes or human activities. These changes can significantly impact biodiversity, species interactions, and the overall health of the environment. Understanding these changes is crucial for assessing environmental health and developing strategies for conservation and resilience.
Ecosystem-based adaptation: Ecosystem-based adaptation refers to the use of biodiversity and ecosystem services to help communities adapt to the impacts of climate change. This approach integrates natural systems into adaptation strategies, promoting resilience and reducing vulnerability by utilizing the services that ecosystems provide. By enhancing natural processes, such as restoring wetlands or conserving forests, communities can mitigate risks associated with climate change while also fostering sustainable development.
Emission Scenarios: Emission scenarios are projections that estimate future greenhouse gas emissions based on different assumptions about socio-economic development, technological advancements, and policy decisions. These scenarios help in understanding how various factors, such as population growth or energy consumption patterns, influence climate change and its impacts, including global sea level trends.
Flood barriers: Flood barriers are structures designed to prevent or mitigate the impact of flooding by blocking or redirecting water. These barriers can be temporary or permanent, and they play a crucial role in protecting infrastructure, homes, and ecosystems from rising water levels due to heavy rainfall, storm surges, or sea level rise. Effective flood barriers are vital as sea levels continue to rise globally, making adaptation strategies increasingly important.
Glacial melt: Glacial melt refers to the process by which glaciers and ice sheets lose mass as ice transforms into water, primarily due to rising global temperatures. This phenomenon contributes significantly to sea level rise and is a key indicator of climate change, impacting global sea level trends and coastal environments.
Global sea level trends: Global sea level trends refer to the long-term changes in the average height of the world's oceans relative to land, primarily influenced by factors such as climate change, melting ice sheets, and thermal expansion of seawater. Understanding these trends is crucial as they have significant implications for coastal communities, ecosystems, and global climate patterns.
Gravitational effects: Gravitational effects refer to the influence of Earth's gravity on the movement of water, which plays a significant role in determining sea level variations. These effects can cause localized changes in sea level due to the redistribution of mass, such as melting ice sheets or the accumulation of sediments, impacting global sea level trends. Understanding these gravitational influences is crucial for accurately predicting future sea level scenarios and assessing coastal resilience.
Groundwater extraction: Groundwater extraction refers to the process of removing water from underground aquifers, primarily through wells, for various uses such as agricultural irrigation, drinking water supply, and industrial processes. This practice can significantly impact the surrounding environment and contribute to issues like land subsidence and changes in local hydrology, which are closely tied to hazards associated with both landslides and global sea level trends.
Infrastructure planning: Infrastructure planning is the systematic process of designing, developing, and maintaining essential physical structures and facilities, such as roads, bridges, water supply systems, and energy sources. This process is critical for accommodating population growth and urbanization, especially in areas vulnerable to environmental changes, such as rising sea levels. By ensuring that infrastructure is resilient and adaptable, communities can better withstand the impacts of climate change and other hazards.
Integrated Coastal Zone Management: Integrated Coastal Zone Management (ICZM) is a process that promotes a sustainable management approach to coastal areas, balancing environmental, economic, social, and cultural objectives. This approach recognizes the interconnectedness of coastal ecosystems and human activities, aiming to address complex issues such as coastal erosion, habitat loss, and socio-economic pressures through coordinated planning and decision-making.
IPCC Projections: IPCC projections refer to the climate forecasts made by the Intergovernmental Panel on Climate Change (IPCC), which provide estimates of future climate conditions based on different greenhouse gas emission scenarios. These projections utilize complex climate models to predict changes in temperature, precipitation, sea levels, and other climate-related factors, helping to inform policymakers and communities about potential impacts and necessary adaptations.
John A. Church: John A. Church is a prominent scientist known for his contributions to understanding global sea level rise and its implications for climate change. His research focuses on the physical processes driving sea level changes, making him a key figure in the field of coastal resilience and environmental science. He has played a significant role in synthesizing data on sea level trends and advocating for actionable responses to mitigate the impacts of rising seas on vulnerable communities.
Managed retreat: Managed retreat is a strategic approach to climate adaptation that involves relocating human populations and infrastructure away from vulnerable coastal areas to reduce risks associated with sea level rise, flooding, and erosion. This concept balances the need for human safety with environmental sustainability by allowing natural coastal processes to occur while minimizing human impact.
National Flood Insurance Program: The National Flood Insurance Program (NFIP) is a federal program in the United States designed to provide flood insurance to property owners, renters, and businesses while promoting sound floodplain management. It connects flood insurance availability with community efforts to reduce flood risk through zoning, land-use planning, and construction standards, influencing various aspects of coastal resilience and risk management.
Nature-based solutions: Nature-based solutions are strategies that utilize natural processes and ecosystems to address societal challenges, particularly in the context of environmental resilience and sustainability. These solutions leverage biodiversity and ecosystem services to mitigate risks, such as flooding or coastal erosion, while also providing benefits like enhanced biodiversity, improved air quality, and recreational opportunities.
Ocean circulation patterns: Ocean circulation patterns refer to the large-scale movement of water in the world's oceans, driven by factors such as wind, temperature differences, salinity variations, and the Earth's rotation. These patterns are crucial for regulating climate and weather systems, influencing sea level trends, and distributing heat and nutrients across marine ecosystems.
Resilient design: Resilient design is an approach to planning and building that aims to create structures and environments capable of withstanding and recovering from adverse conditions, such as natural disasters and climate change impacts. This concept emphasizes the importance of flexibility, adaptability, and sustainability in architectural and engineering practices, ensuring that developments can cope with rising sea levels and other environmental challenges.
Saltwater Intrusion: Saltwater intrusion is the process where saltwater encroaches into freshwater aquifers, often due to over-extraction of groundwater and rising sea levels. This phenomenon is increasingly relevant as climate change contributes to both sea level rise and changes in precipitation patterns, directly affecting coastal water resources. As aquifers become contaminated with saltwater, they lose their ability to provide clean drinking water, impacting ecosystems and communities that rely on these sources.
Satellite altimetry: Satellite altimetry is a remote sensing technology that measures the distance between a satellite and the Earth's surface to determine variations in sea surface height. This technique provides critical data for monitoring sea level rise, understanding ocean dynamics, and assessing changes in regional sea levels, making it essential for various studies related to coastal resilience and climate change.
Seawalls: Seawalls are coastal defense structures designed to protect shorelines from erosion and damage caused by waves, storm surges, and high tides. They serve to absorb and reflect wave energy, reducing the impact on the land behind them, which is crucial as storm patterns change and sea levels rise. These structures play a vital role in adaptation strategies for protecting coastal communities and infrastructure from climate-related threats.
Thermal expansion: Thermal expansion is the process by which matter increases in volume as its temperature rises. This phenomenon is significant in the context of oceans, as the warming of seawater due to climate change leads to an increase in ocean volume, contributing to rising sea levels. Understanding thermal expansion is crucial for analyzing global sea level trends and regional variations, particularly how different areas may experience varying impacts from climate-induced changes in temperature.
Tide gauges: Tide gauges are instruments used to measure the change in sea level over time, specifically capturing the height of the water surface relative to a fixed point on land. These gauges provide critical data on tides and long-term sea level trends, enabling scientists to understand patterns related to climate change, land subsidence, and oceanographic processes.
Vertical land movements: Vertical land movements refer to the geological processes that result in the elevation or subsidence of land surfaces over time. These movements can be caused by natural factors such as tectonic activity, glacial rebound, and sediment compaction, or by human activities like mining and groundwater extraction. Understanding these movements is crucial as they directly impact sea level changes and coastal resilience.
Vulnerability Assessment: A vulnerability assessment is a systematic process used to identify, evaluate, and prioritize the weaknesses and risks faced by a community, ecosystem, or infrastructure due to environmental hazards. This assessment helps in understanding how various factors, such as coastal erosion, extreme weather events, and rising sea levels, can impact communities and their resilience against these threats.
William A. Nierenberg: William A. Nierenberg was a prominent American physicist and oceanographer known for his extensive contributions to climate science, particularly in understanding global sea level rise and trends. He served as the director of the Scripps Institution of Oceanography and played a significant role in various scientific committees that shaped research on climate change and its impacts, connecting the dots between scientific inquiry and policy-making.
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