scholarly journals Coastal Louisiana in crisis: Subsidence or sea level rise?

Eos ◽  
2006 ◽  
Vol 87 (45) ◽  
pp. 493 ◽  
Author(s):  
Juan L. González ◽  
Torbjörn E. Tornqvist
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Louisiana

scholarly journals Tipping points of Mississippi Delta marshes due to accelerated sea-level rise

2020 ◽  
Vol 6 (21) ◽  
pp. eaaz5512 ◽  
Author(s):  
Torbjörn E. Törnqvist ◽  
Krista L. Jankowski ◽  
Yong-Xiang Li ◽  
Juan L. González
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Mississippi Delta ◽  
Time Windows ◽  
Open Water ◽  
Tipping Points ◽  
Coastal Marshes ◽  
Short Term ◽  
Global Sea Level ◽  
Coastal Louisiana

Coastal marshes are threatened by relative sea-level (RSL) rise, yet recent studies predict marsh survival even under the high rates of RSL rise expected later in this century. However, because these studies are mostly based on short-term records, uncertainty persists about the longer-term vulnerability of coastal marshes. We present an 8500-year-long marsh record from the Mississippi Delta, showing that at rates of RSL rise exceeding 6 to 9 mm year−1, marsh conversion into open water occurs in about 50 years. At rates of RSL rise exceeding ~3 mm year−1, marsh drowning occurs within a few centuries. Because present-day rates of global sea-level rise already surpass this rate, submergence of the remaining ~15,000 km2 of marshland in coastal Louisiana is probably inevitable. RSL-driven tipping points for marsh drowning vary geographically, and those for the Mississippi Delta may be lower than elsewhere. Nevertheless, our findings highlight the need for consideration of longer time windows in determining the vulnerability of coastal marshes worldwide.

scholarly journals Measuring rates of present-day relative sea-level rise in low-elevation coastal zones: A critical evaluation

2018 ◽  
Author(s):  
Molly E. Keogh ◽  
Torbjörn E. Törnqvist
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Surface ◽  
Tide Gauge ◽  
Tide Gauges ◽  
Coastal Zones ◽  
Tide Gauge Data ◽  
Relative Sea Level ◽  
Gauge Data ◽  
Coastal Louisiana

Abstract. Although tide gauges are the primary source of data used to calculate multi-decadal to century-scale rates of relative sea-level change, we question the reliability of tide-gauge data in rapidly subsiding low-elevation coastal zones (LECZs). Tide gauges measure relative sea-level rise (RSLR) with respect to the base of associated benchmarks. Focusing on coastal Louisiana, the largest LECZ in the United States, we find that these benchmarks (n = 35) are anchored an average of 21.5 m below the land surface. Because at least 60 % of subsidence occurs in the top 5–10 m of the sediment column in this area, tide gauges in coastal Louisiana do not capture the primary contributor to RSLR. Similarly, GPS stations (n = 10) are anchored an average of > 14.3 m below the land surface and therefore also do not capture shallow subsidence. As a result, tide gauges and GPS stations in coastal Louisiana, and likely in LECZs worldwide, systematically underestimate rates of RSLR as experienced at the land surface. We present an alternative approach that explicitly measures RSLR in LECZs with respect to the land surface and eliminates the need for tide-gauge data. Shallow subsidence is measured by rod surface-elevation table‒marker horizons (RSET-MHs) and added to measurements of deep subsidence from GPS data, plus sea-level rise from satellite altimetry. We show that for a LECZ the size of coastal Louisiana (25,000–30,000 km2), about 40 RSET-MH instruments suffice to collect useful data. Rates of RSLR obtained from this approach are substantially higher than rates as inferred from tide-gauge data. We therefore conclude that LECZs may be at higher risk of flooding, and within a shorter time horizon, than previously assumed.

scholarly journals A multiple knowledge approach for adaptation to environmental change: lessons learned from coastal Louisiana's tribal communities

2014 ◽  
Vol 21 (1) ◽  
pp. 61 ◽  
Author(s):  
Julie Koppel Maldonado
Keyword(s):  
Environmental Change ◽  
Political Ecology ◽  
Sea Level Rise ◽  
Sea Level ◽  
Environmental Changes ◽  
Policy Implications ◽  
Governance Structures ◽  
Forced Displacement ◽  
Tribal Communities ◽  
Coastal Louisiana

Environmental changes, such as sea level rise, are forcibly displacing communities around the world. Forced displacement, inadequate governance mechanisms to address relocation and economic-based adaptation and restoration efforts are leading to devastating social, cultural, health, and economic consequences for the people and communities affected. This article focuses on three tribal communities in coastal Louisiana that are experiencing rapid environmental change and risk of displacement due to historical discriminatory processes, oil and dam-related development projects, oil disasters, increased exposure to hurricanes, and relative sea level rise. Focusing on the political ecology of the communities' experiences of environmental change, including the impacts of displacement and decisions to stay in-place vs. relocate, this paper addresses broader issues of adaptive governance structures and policy implications. Building on Bronen's (2011) rights-based approach to adaptation and Shearer's (2012) approach to a political ecology of adaptation, I argue that governance structures should be put in place that support communities' in-situ adaptation efforts or, if the community decides its current location is no longer inhabitable, to assist community-led relocation efforts. Multiple forms of knowledge should be incorporated into and should inform the structures supporting the adaptation process. I highlight the social, political, environmental and economic context within which environmental changes are occurring in coastal Louisiana through discussion on the loss of the commons, the creation of an energy sacrifice zone, costbenefit based restoration efforts and forced displacement and relocation.Key words: Environmental change, displacement, relocation, adaptation

Layering of Natural and Human-Caused Disasters in the Context of Sea Level Rise: Coastal Louisiana Communities at the Edge

2015 ◽  
pp. 225-238 ◽  
Author(s):  
Shirley Laska ◽  
Kristina Peterson ◽  
Crystlyn Rodrigue ◽  
Tia Cosse’ ◽  
Rosina Philippe ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Louisiana

Modelling coastal marsh stability in response to sea level rise: a case study in coastal Louisiana, USA

1992 ◽  
Vol 64 (1) ◽  
pp. 47-64 ◽  
Author(s):  
Gail L. Chmura ◽  
Robert Costanza ◽  
Elisabeth C. Kosters
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Marsh ◽  
Coastal Louisiana

scholarly journals Measuring rates of present-day relative sea-level rise in low-elevation coastal zones: a critical evaluation

Ocean Science ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 61-73 ◽  
Author(s):  
Molly E. Keogh ◽  
Torbjörn E. Törnqvist
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Surface ◽  
Tide Gauge ◽  
Tide Gauges ◽  
Coastal Zones ◽  
Tide Gauge Data ◽  
Relative Sea Level ◽  
Gauge Data ◽  
Coastal Louisiana

Abstract. Although tide gauges are the primary source of data used to calculate multi-decadal- to century-scale rates of relative sea-level change, we question the usefulness of tide-gauge data in rapidly subsiding low-elevation coastal zones (LECZs). Tide gauges measure relative sea-level rise (RSLR) with respect to the base of associated benchmarks. Focusing on coastal Louisiana, the largest LECZ in the United States, we find that these benchmarks (n=35) are anchored an average of 21.5 m below the land surface. Because at least 60 % of subsidence occurs in the top 5 m of the sediment column in this area, tide gauges in coastal Louisiana do not capture the primary contributor to RSLR. Similarly, global navigation satellite system (GNSS) stations (n=10) are anchored an average of > 14.3 m below the land surface and therefore also do not capture shallow subsidence. As a result, tide gauges and GNSS stations in coastal Louisiana, and likely in LECZs worldwide, systematically underestimate rates of RSLR as experienced at the land surface. We present an alternative approach that explicitly measures RSLR in LECZs with respect to the land surface and eliminates the need for tide-gauge data in this context. Shallow subsidence is measured by rod surface-elevation table–marker horizons (RSET-MHs) and added to measurements of deep subsidence from GNSS data, plus sea-level rise from satellite altimetry. We show that for an LECZ the size of coastal Louisiana (25 000–30 000 km2), about 40 RSET-MH instruments suffice to collect useful data. Rates of RSLR obtained from this approach are substantially higher than rates as inferred from tide-gauge data. We therefore conclude that LECZs may be at higher risk of flooding within a shorter time horizon than previously assumed.

Glacial Contributions to 21st Century Sea Level Rise

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Kate Wheeling
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Mass Change ◽  
Sources Of Uncertainty

Researchers identify the main sources of uncertainty in projections of global glacier mass change, which is expected to add about 8–16 centimeters to sea level, through this century.

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