Limits on the adaptability of coastal marshes to rising sea level

Abstract

[1] Assumptions of a static landscape inspire predictions that about half of the world's coastal wetlands will submerge during this century in response to sea-level acceleration. In contrast, we use simulations from five numerical models to quantify the conditions under which ecogeomorphic feedbacks allow coastal wetlands to adapt to projected changes in sea level. In contrast to previous sea-level assessments, we find that non-linear feedbacks among inundation, plant growth, organic matter accretion, and sediment deposition, allow marshes to survive conservative projections of sealevel rise where suspended sediment concentrations are greater than ∼20 mg/L. Under scenarios of more rapid sea-level rise (e.g., those that include ice sheet melting), marshes will likely submerge near the end of the 21st century. Our results emphasize that in areas of rapid geomorphic change, predicting the response of ecosystems to climate change requires consideration of the ability of biological processes to modify their physical environment.

The secret gardener: vegetation and the emergence of biogeomorphic patterns in tidal environments

“…In particular, it is seen that thresholds exist above which the marsh and the tidal flat equilibria no longer exist (R > 9.7 mm yr −1 and R > 15.5 mm yr −1 , respectively, for the values of H and C 0 assumed in figure 1). These thresholds signal transitions to regimes characterized by a reduced number of possible biogeomorphic patterns and mark limits to the resilience of tidal systems as we currently know them [2,20,39]. In the multi-species case (not reproduced here for brevity), because organic soil production increases monotonically with elevation, no stable marsh equilibrium is possible for C 0 = 20 g m 3 and R = 8.5 mm yr −1 , and only subtidal platform and tidal flat equilibria exist (a marsh equilibrium can be recovered, however, either by lowering the value of R or by increasing the value of C 0 ).…”

“…[1][2][3][4]). An outcome of such pursuit is the generation of some striking biological and morphological patterns at different scales.…”

A global standard for monitoring coastal wetland vulnerability to accelerated sea-level rise

“…Coastal wetland models continue to evolve, and vary in the extent that they incorporate complex ecological and physical processes occurring at the surface and shallow subsurface levels 27 . Recent numerical models that integrate non linear feedbacks among inundation, plant growth, organic matter accretion and mineral sediment deposition have been developed to identify the circumstances that lead to coastal wetland resilience and thresholds that result in the submergence of coastal wetlands 27,28 . These models are addressing a major knowledge gap in understanding the limits of wetland adaptation to SLR 28 and the processes affecting coastal marsh response.…”

“…Recent numerical models that integrate non linear feedbacks among inundation, plant growth, organic matter accretion and mineral sediment deposition have been developed to identify the circumstances that lead to coastal wetland resilience and thresholds that result in the submergence of coastal wetlands 27,28 . These models are addressing a major knowledge gap in understanding the limits of wetland adaptation to SLR 28 and the processes affecting coastal marsh response. Indeed, marshes are also subjected to other external drivers that may interact with inundation and lead to wetland loss apart from changes in surface elevation.…”

Tropical limestone forest resilience and late Pleistocene foraging during MIS-2 in the Tràng An massif, Vietnam

“…While the corpus of literature on the impact to coastal habitats globally gathers apace (e.g. Virah-Sawmy et al 2009;Kirwan et al 2010;Holland 2012;Mendoza-González et al 2013;Hunter et al 2015), with few recent exceptions (e.g. Wetzel et al 2012;Faridah-Hanum et al 2014;Latinne et al 2015) the effect of climate change on coastal tropical terrestrial habitats is still an underrepresented field, and a body of research to which this study contributes.…”