Sea-Level Rise and Climate Change Impacts to Reefs Completed
Learn how the USGS studies sea-level rise and climate change impacts to coral reefs.
This study is part of the USGS Coral Reef Project.
The Problem
There is a growing body of evidence indicating that the rate of sea-level rise has increased relative to the past century and will continue to increase in the 21st century; that evidence has recently been summarized by the Intergovernmental Panel on Climate Change (IPCC). If all aspects of reef morphology—colony size and shape, cross-reef relief, surface rugosity, and so on—keep pace with the rising sea levels, then it is likely that changes in depth-controlled physical processes will be minimal to non-detectible. However, based on rates of vertical reef accretion in Hawaiʻi and throughout the Pacific (which are an order of magnitude smaller than predicted rates of sea-level rise), it is unlikely that reefs there and other locations will keep pace, and their inability to do so will lead to subtle but important changes in selected physical processes on some coral reefs.
In addition, recent studies indicate the flux of submarine groundwater discharge from land to coral reefs in Hawaiʻi and other high islands is substantial, and often significantly colder and enriched in terrestrial-derived nutrients than surrounding seawater. Ecosystem functions of submarine groundwater discharge to coral reef ecosystems are not quantified but can be hypothesized to (1) buffer thermal stress (bleaching) in corals experiencing warming, and (2) supply nutrients to otherwise oligotrophic coastal waters. While an excess of the latter has been observed to cause complete phase shifts in the form of wholesale loss of coral and replacement by macroalgae, the role of the former has not been tested. Both may be significantly altered by impending climate change and proposed land use that alter groundwater quantity, quality, flux, composition, and fate, especially in rapidly developing areas. This effort is focused on submarine groundwater discharge, its role in shaping coral reef ecosystem structure, and the ecosystem services it provides.
The Approach
The overall objective of this research effort is to better understand how climate change may impact coral reefs. Achievement of this objective requires an understanding of the physical parameters driving change in coral reefs and the resulting ecosystem processes. The goals of this effort are to:
- How will reefs respond to rapid sea-level rise at a decadal time-scale?
- How will increased wave energy and altered circulation across reefs affect circulation and sediment, nutrient, contaminant, and larval dynamics?
- Do thresholds exist in the rate of sea-level rise that would push a reef ecosystem from a state of stability to one of net loss?
- How may changes in precipitation, recharge, and human-induced withdraws impact submarine groundwater discharge to the coastal zone?
- How will coral reefs respond to variations in submarine groundwater discharge predicted to occur due to climate change?
The approach to these interdisciplinary studies will rely on a combination of field measurements and physics-based numerical monitoring. We use a wide range of tools to try to answer these questions, including: oceanographic instruments (for example, acoustic Doppler current profilers, wave/tide gauges, temperature sensors, salinity sensors, chemical sensors) mounted on the seabed or on moorings, water-column profilers with similar suites of sensors, coral cores, geophysical water-column and sub-bottom surveys, and physics-based numerical models.
Below are data releases associated with this project.
Below are publications associated with this study.
Projected atoll shoreline and run-up changes in response to sea-level rise and varying large wave conditions at Wake and Midway Atolls, Northwestern Hawaiian Islands
Rare earth element behavior during groundwater – seawater mixing along the Kona Coast of Hawaii
Identification and classification of very low frequency waves on a coral reef flat
Changes to extreme wave climates of islands within the Western Tropical Pacific throughout the 21st century under RCP 4.5 and RCP 8.5, with implications for island vulnerability and sustainability
Observations of wave transformation over a fringing coral reef and the importance of low-frequency waves and offshore water levels to runup, overwash, and coastal flooding
Reconstructing surface ocean circulation with 129I time series records from corals
Coral calcification and ocean acidification
The influence of coral reefs and climate change on wave-driven flooding of tropical coastlines
Ground-truthing electrical resistivity methods in support of submarine groundwater discharge studies: Examples from Hawaii, Washington, and California
Modeled changes in extreme wave climates of the tropical Pacific over the 21st century: Implications for U.S. and U.S.-Affiliated atoll islands
A Geochemical and Geophysical Assessment of Coastal Groundwater Discharge at Select Sites in Maui and O’ahu, Hawai’i
The effectiveness of coral reefs for coastal hazard risk reduction and adaptation
- Overview
Learn how the USGS studies sea-level rise and climate change impacts to coral reefs.
This study is part of the USGS Coral Reef Project.
The Problem
There is a growing body of evidence indicating that the rate of sea-level rise has increased relative to the past century and will continue to increase in the 21st century; that evidence has recently been summarized by the Intergovernmental Panel on Climate Change (IPCC). If all aspects of reef morphology—colony size and shape, cross-reef relief, surface rugosity, and so on—keep pace with the rising sea levels, then it is likely that changes in depth-controlled physical processes will be minimal to non-detectible. However, based on rates of vertical reef accretion in Hawaiʻi and throughout the Pacific (which are an order of magnitude smaller than predicted rates of sea-level rise), it is unlikely that reefs there and other locations will keep pace, and their inability to do so will lead to subtle but important changes in selected physical processes on some coral reefs.
In addition, recent studies indicate the flux of submarine groundwater discharge from land to coral reefs in Hawaiʻi and other high islands is substantial, and often significantly colder and enriched in terrestrial-derived nutrients than surrounding seawater. Ecosystem functions of submarine groundwater discharge to coral reef ecosystems are not quantified but can be hypothesized to (1) buffer thermal stress (bleaching) in corals experiencing warming, and (2) supply nutrients to otherwise oligotrophic coastal waters. While an excess of the latter has been observed to cause complete phase shifts in the form of wholesale loss of coral and replacement by macroalgae, the role of the former has not been tested. Both may be significantly altered by impending climate change and proposed land use that alter groundwater quantity, quality, flux, composition, and fate, especially in rapidly developing areas. This effort is focused on submarine groundwater discharge, its role in shaping coral reef ecosystem structure, and the ecosystem services it provides.
The Approach
The overall objective of this research effort is to better understand how climate change may impact coral reefs. Achievement of this objective requires an understanding of the physical parameters driving change in coral reefs and the resulting ecosystem processes. The goals of this effort are to:
- How will reefs respond to rapid sea-level rise at a decadal time-scale?
- How will increased wave energy and altered circulation across reefs affect circulation and sediment, nutrient, contaminant, and larval dynamics?
- Do thresholds exist in the rate of sea-level rise that would push a reef ecosystem from a state of stability to one of net loss?
- How may changes in precipitation, recharge, and human-induced withdraws impact submarine groundwater discharge to the coastal zone?
- How will coral reefs respond to variations in submarine groundwater discharge predicted to occur due to climate change?
The approach to these interdisciplinary studies will rely on a combination of field measurements and physics-based numerical monitoring. We use a wide range of tools to try to answer these questions, including: oceanographic instruments (for example, acoustic Doppler current profilers, wave/tide gauges, temperature sensors, salinity sensors, chemical sensors) mounted on the seabed or on moorings, water-column profilers with similar suites of sensors, coral cores, geophysical water-column and sub-bottom surveys, and physics-based numerical models.
- Data
Below are data releases associated with this project.
- Publications
Below are publications associated with this study.
Filter Total Items: 40Projected atoll shoreline and run-up changes in response to sea-level rise and varying large wave conditions at Wake and Midway Atolls, Northwestern Hawaiian Islands
Atoll islands are dynamic features that respond to seasonal alterations in wave conditions and sea level. It is unclear how shoreline wave run-up and erosion patterns along these low elevation islands will respond to projected sea-level rise (SLR) and changes in wave climate over the next century, hindering communities' preparation for the future. To elucidate how these processes may respond to clAuthorsJames B. Shope, Curt D. Storlazzi, Ron HoekeRare earth element behavior during groundwater – seawater mixing along the Kona Coast of Hawaii
Groundwater and seawater samples were collected from nearshore wells and offshore along the Kona Coast of the Big Island of Hawaii to investigate rare earth element (REE) behavior in local subterranean estuaries. Previous investigations showed that submarine groundwater discharge (SGD) is the predominant flux of terrestrial waters to the coastal ocean along the arid Kona Coast of Hawaii. GroundwatAuthorsKaren H. Johannesson, C. Dianne Palmore, Joseph Fackrell, Nancy G. Prouty, Peter W. Swarzenski, Darren A. Chevis, Katherine Telfeyan, Christopher D. White, David J. BurdigeIdentification and classification of very low frequency waves on a coral reef flat
Very low frequency (VLF, 0.001–0.005 Hz) waves are important drivers of flooding of low-lying coral reef-islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a 5 month data set of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the Marshall Islands, the observed VLF motions were categorizedAuthorsMatthijs Gawehn, Ap van Dongeran, Arnold van Rooijen, Curt D. Storlazzi, Olivia Cheriton, Ad ReniersChanges to extreme wave climates of islands within the Western Tropical Pacific throughout the 21st century under RCP 4.5 and RCP 8.5, with implications for island vulnerability and sustainability
Waves are the dominant influence on coastal morphology and ecosystem structure of tropical Pacific islands. Wave heights, periods, and directions for the 21st century were projected using near-surface wind fields from four atmosphere-ocean coupled global climate models (GCM) under representative concentration pathways (RCP) 4.5 and 8.5. GCM-derived wind fields forced the global WAVEWATCH-III waveAuthorsJames B. Shope, Curt D. Storlazzi, Li H. Erikson, Christie HegermillerObservations of wave transformation over a fringing coral reef and the importance of low-frequency waves and offshore water levels to runup, overwash, and coastal flooding
Many low-lying tropical islands are susceptible to sea level rise and often subjected to overwash and flooding during large wave events. To quantify wave dynamics and wave-driven water levels on fringing coral reefs, a 5 month deployment of wave gauges and a current meter was conducted across two shore-normal transects on Roi-Namur Island in the Republic of the Marshall Islands. These observationsAuthorsOlivia Cheriton, Curt D. Storlazzi, Kurt J. RosenbergerReconstructing surface ocean circulation with 129I time series records from corals
The long-lived radionuclide 129I (half-life: 15.7 × 106 yr) is well-known as a useful environmental tracer. At present, the global 129I in surface water is about 1–2 orders of magnitude higher than pre-1960 levels. Since the 1990s, anthropogenic 129I produced from industrial nuclear fuels reprocessing plants has been the primary source of 129I in marine surface waters of the Atlantic and around thAuthorsChing-Chih Chang, George S. Burr, A. J. Timothy Jull, Joellen L. Russell, Dana Biddulph, Lara White, Nancy G. Prouty, Yue-Gau Chen, Chuan-Chou Shen, Weijian Zhou, Doan Dinh LamCoral calcification and ocean acidification
Over 60 years ago, the discovery that light increased calcification in the coral plant-animal symbiosis triggered interest in explaining the phenomenon and understanding the mechanisms involved. Major findings along the way include the observation that carbon fixed by photosynthesis in the zooxanthellae is translocated to animal cells throughout the colony and that corals can therefore live as autAuthorsPaul L. Jokiel, Christopher P. Jury, Ilsa B. KuffnerThe influence of coral reefs and climate change on wave-driven flooding of tropical coastlines
A numerical model, XBeach, calibrated and validated on field data collected at Roi-Namur Island on Kwajalein Atoll in the Republic of Marshall Islands, was used to examine the effects of different coral reef characteristics on potential coastal hazards caused by wave-driven flooding and how these effects may be altered by projected climate change. The results presented herein suggest that coasts fAuthorsEllen Quataert, Curt D. Storlazzi, Arnold van Rooijen, Ap van Dongeren, Olivia CheritonGround-truthing electrical resistivity methods in support of submarine groundwater discharge studies: Examples from Hawaii, Washington, and California
Submarine groundwater discharge (SGD) is an important conduit that links terrestrial and marine environments. SGD conveys both water and water-borne constituents into coastal waters, where these inflows may impact near-shore ecosystem health and sustainability. Multichannel electrical resistivity techniques have proven to be a powerful tool to examine scales and dynamics of SGD and SGD forcings. HAuthorsCordell Johnson, Peter W. Swarzenski, Christina M. Richardson, Christopher G. Smith, Kevin D. Kroeger, Priya M. GanguliModeled changes in extreme wave climates of the tropical Pacific over the 21st century: Implications for U.S. and U.S.-Affiliated atoll islands
Wave heights, periods, and directions were forecast for 2081–2100 using output from four coupled atmosphere–ocean global climate models for representative concentration pathway scenarios RCP4.5 and RCP8.5. Global climate model wind fields were used to drive the global WAVEWATCH-III wave model to generate hourly time-series of bulk wave parameters for 25 islands in the mid to western tropical PacifAuthorsJ.B. Shope, Curt D. Storlazzi, Li H. Erikson, C.A. HegermillerA Geochemical and Geophysical Assessment of Coastal Groundwater Discharge at Select Sites in Maui and O’ahu, Hawai’i
This chapter summarizes fieldwork conducted to derive new estimates of coastal groundwater discharge and associated nutrient loadings at select coastal sites in Hawai’i, USA. Locations for this work were typically identified based on pronounced, recent ecosystem degradation that may at least partially be attributable to sustained coastal groundwater discharge. Our suite of tools used to evaluate gAuthorsPeter W. Swarzenski, Curt D. Storlazzi, M.L. Dalier, C.R. Glenn, C.G. SmithThe effectiveness of coral reefs for coastal hazard risk reduction and adaptation
The world’s coastal zones are experiencing rapid development and an increase in storms and flooding. These hazards put coastal communities at heightened risk, which may increase with habitat loss. Here we analyse globally the role and cost effectiveness of coral reefs in risk reduction. Meta-analyses reveal that coral reefs provide substantial protection against natural hazards by reducing wave enAuthorsFilippo Ferrario, Michael W. Beck, Curt D. Storlazzi, Fiorenza Micheli, Christine C. Shepard, Laura Airoldi