Runaway Barrier Island Transgression Concept: Global Case Studies

FitzGerald, Duncan M.; Hein, Christopher J.; Hughes, Zoë; Kulp, Mark A.; Georgiou, Ioannis Y.; Miner, Michael D.

doi:10.1007/978-3-319-68086-6_1

Cited by 39 publications

(36 citation statements)

References 138 publications

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“…For instance, previous work suggests that two‐way feedbacks between barrier islands and their associated backbarrier environments can result in threshold behaviors that can in turn lead to a whole‐scale reorganization of the barrier system (Carrasco et al, ; Deaton et al, ; FitzGerald et al, ; Lauzon et al, ; Lorenzo‐Trueba & Mariotti, ; Walters et al, ). RSL rise and wave action can cause not only barrier shoreline retreat but also drastic changes in backbarrier marsh vegetation, including marsh loss (J. P. Donnelly & Bertness, ; Kirwan & Megonigal, ; Lorenzo‐Trueba & Mariotti, ; Mariotti & Fagherazzi, ).…”

Section: Coastal Flooding In a Dynamic Physical Environmentmentioning

confidence: 99%

“…RSL rise and wave action can cause not only barrier shoreline retreat but also drastic changes in backbarrier marsh vegetation, including marsh loss (J. P. Donnelly & Bertness, ; Kirwan & Megonigal, ; Lorenzo‐Trueba & Mariotti, ; Mariotti & Fagherazzi, ). The loss of marshlands would change the hypsometry of the backbarrier, increasing tidal exchange between the ocean and backbarrier and enhancing the rate of barrier landward migration, which in turn could accelerate barrier disintegration and drowning (FitzGerald et al, ; Lorenzo‐Trueba & Mariotti, ). In general, this work highlights that backbarrier environment characteristics that are typically not directly related to barrier evolution—such as the extent of marsh platforms, lagoon fetch, suspended sediment concentrations in the lagoon, and the mainland slope—could play a major role in the long‐term barrier response to RSL rise.…”

Section: Coastal Flooding In a Dynamic Physical Environmentmentioning

confidence: 99%

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Usable Science for Managing the Risks of Sea‐Level Rise

et al. 2019

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Sea-level rise sits at the frontier of usable climate climate change research, because it involves natural and human systems with long lags, irreversible losses, and deep uncertainty. For example, many of the measures to adapt to sea-level rise involve infrastructure and land-use decisions, which can have multigenerational lifetimes and will further influence responses in both natural and human systems. Thus, sea-level science has increasingly grappled with the implications of (1) deep uncertainty in future climate system projections, particularly of human emissions and ice sheet dynamics; (2) the overlay of slow trends and high-frequency variability (e.g., tides and storms) that give rise to many of the most relevant impacts; (3) the effects of changing sea level on the physical exposure and vulnerability of ecological and socioeconomic systems; and (4) the challenges of engaging stakeholder communities with the scientific process in a way that genuinely increases the utility of the science for adaptation decision making. Much fundamental climate system research remains to be done, but many of the most critical issues sit at the intersection of natural sciences, social sciences, engineering, decision science, and political economy. Addressing these issues demands a better understanding of the coupled interactions of mean and extreme sea levels, coastal geomorphology, economics, and migration; decision-first approaches that identify and focus research upon those scientific uncertainties most relevant to concrete adaptation choices; and a political economy that allows usable science to become used science.Plain Language Summary The impacts of sea-level rise pose growing threats to coastal communities, economies, and ecosystems, and decisions made today-in areas like land-use policies, coastal development, and infrastructure investment-will affect exposure and vulnerability for generations to come. Thus, the usability of sea-level science is a pressing concern. Ensuring usability requires grappling with deep uncertainty in long-term sea-level projections, the relationship between long-term trends and the impacts of short-lived extreme events, and the ways in which the physical coast, as well as people and ecosystems along the coast, respond to increasingly frequent flooding. At the same time, it also requires more extensive and deliberate stakeholder engagement throughout the scientific process, as well as cognizance of the political economy of linking stakeholder-engaged science to action.

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Section: Coastal Flooding In a Dynamic Physical Environmentmentioning

confidence: 99%

Section: Coastal Flooding In a Dynamic Physical Environmentmentioning

confidence: 99%

Usable Science for Managing the Risks of Sea‐Level Rise

et al. 2019

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“…Barrier islands are highly vulnerable to global climate change because of the tight coupling among island ecological processes, geomorphological processes, and oceanic/atmospheric drivers of disturbance (e.g., hurricanes, nor'easters, sea-level rise) (Arkema et al, 2013;Zinnert, Stallins, Brantley, & Young, 2017). The processes which maintain these islands are being disrupted by rising sea level and increased storm intensity and frequency (FitzGerald et al, 2018). Barrier island systems are the front to >20,000 km or ~10% of coastline globally (Stutz & Pilkey, 2011).…”

Section: Introductionmentioning

confidence: 99%

Connectivity in coastal systems: Barrier island vegetation influences upland migration in a changing climate

Zinnert

Via

Nettleton

et al. 2019

Global Change Biology

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Due to their position at the land–sea interface, barrier islands are vulnerable to both oceanic and atmospheric climate change‐related drivers. In response to relative sea‐level rise, barrier islands tend to migrate landward via overwash processes which deposit sediment onto the backbarrier marsh, thus maintaining elevation above sea level. In this paper, we assess the importance of interior upland vegetation and sediment transport (from upland to marsh) on the movement of the marsh–upland boundary in a transgressive barrier system along the mid‐Atlantic Coast. We hypothesize that recent woody expansion is altering the rate of marsh to upland conversion. Using Landsat imagery over a 32 year time period (1984–2016), we quantify transitions between land cover (bare, grassland, woody vegetation, and marsh) and the marsh–upland boundary. We find that the Virginia Barrier Islands have both gains and losses in backbarrier marsh and upland, with 19% net loss from the system during the timeframe of the study and increased variance in marsh to upland conversion. This is consistent with recent work indicating a shift toward increasing rates of landward barrier island migration. Despite a net loss of upland area, macroclimatic winter warming resulted in 41% increase in woody vegetation in protected, low‐elevation areas, introducing new ecological scenarios that increase resistance to sediment movement from upland to marsh. Our analysis demonstrates how the interplay between elevation and interior island vegetative cover influences landward migration of the boundary between upland and marsh (a previously underappreciated indicator that an island is migrating), and thus, the importance of including ecological processes in the island interior into coastal modeling of barrier island migration and sediment movement across the barrier landscape.

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“…The correlation between elevation and the UVVR is most readily explained by the development of marshes along a preexisting transgressive coastal landscape (FitzGerald et al, 2018). In the initial response to sealevel rise, hydrodynamic processes extract sediment from the back-barrier system to compensate for increased depth (i.e., accommodation space).…”

Section: Marshes In a Transgressive Landscapementioning

confidence: 99%

Are Elevation and Open‐Water Conversion of Salt Marshes Connected?

Ganju

Defne

Fagherazzi

2020

Geophysical Research Letters

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Salt marsh assessments focus on vertical metrics such as accretion or lateral metrics such as open‐water conversion, without exploration of how the dimensions are related. We exploited a novel geospatial data set to explore how elevation is related to the unvegetated‐vegetated marsh ratio (UVVR), a lateral metric, across individual marsh “units” within four estuarine‐marsh systems. We find that elevation scales consistently with the UVVR across systems, with lower elevation units demonstrating more open‐water conversion and higher UVVRs. A normalized elevation‐UVVR relationship converges across systems near the system‐mean elevation and a UVVR of 0.1, a critical threshold identified by prior studies. This indicates that open‐water conversion becomes a dominant lateral instability process at a relatively conservative elevation threshold. We then integrate the UVVR and elevation to yield lifespan estimates, which demonstrate that higher elevation marshes are more resilient to internal deterioration, with an order‐of‐magnitude longer lifespan than predicted for lower elevation marshes.

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Runaway Barrier Island Transgression Concept: Global Case Studies

Cited by 39 publications

References 138 publications

Usable Science for Managing the Risks of Sea‐Level Rise

Usable Science for Managing the Risks of Sea‐Level Rise

Connectivity in coastal systems: Barrier island vegetation influences upland migration in a changing climate

Are Elevation and Open‐Water Conversion of Salt Marshes Connected?

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