Cultural ecosystem services caught in a ‘coastal squeeze’ between sea level rise and urban expansion

Intertidal coastal wetlands, including tidal marshes and mangrove forests, are at risk of disappearing under the influence of global sea level rise (SLR). Loss of their ecosystem services could significantly impact global carbon budgets, increase coastal erosion and flooding and lead to loss of fisheries, particularly along densely populated coastal zones such as large estuaries and deltas. Regional to global-scale projections suggest a reduction in present-day coastal wetland area by 20% to 90% in response to projected rates of future SLR. Recent studies have highlighted the importance of coastal squeeze, i.e. the inhibition of inland migration of tidal coastal wetlands due to the existence of anthropogenic infrastructure, in combination with wetland loss due to sea level rise, which is aggravated by a global decline in coastal sediment supply.Nature-based adaptation, consisting of the reservation or creation of space for inland wetland expansion, is widely regarded as a promising strategy to counteract coastal squeeze and create/restore natural habitats through inland migration. Based on global and regional modelling outputs, this paper discusses how different scenarios of global population growth, expected declines in global sediment supply, delta subsidence and various coastal management strategies impact on global areas of intertidal coastal wetlands, and coastal squeeze in particular. For example, we estimate that until the year 2100 up to 280,000 km2 of coastal wetlands may be lost due to coastal squeeze. If strategically implemented on a regional to global scale nature-based solutions to coastal management could increase the global total area of intertidal coastal wetlands by up to 60%.However our current understanding of this process is very limited, partly due to the limited field evidence in sedimentary archives (e.g. during the early Holocene where SLR were high). We argue that this is related to the combined effects of wetland inland migration and wetland drowning during periods of high SLR rates, raising the question as to whether or not future coastal wetland will be able to provide ecosystem services comparable to those of natural systems.

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Approaching Sea-Level Rise (SLR) Change: Strengthening Local Responses to Sea-Level Rise and Coping with Climate Change in Northern Mozambique

Journal of Marine Science and Engineering ◽

10.3390/jmse9020205 ◽

2021 ◽

Vol 9 (2) ◽

pp. 205

Author(s):

Serafino Afonso Rui Mucova ◽

Ulisses Miranda Azeiteiro ◽

Walter Leal Filho ◽

Carina Lurdes Lopes ◽

João Miguel Dias ◽

...

Keyword(s):

Ecosystem Services ◽

Sea Level Rise ◽

Sea Level ◽

North Coast ◽

Coastal Regions ◽

Mean Sea Level ◽

Representative Concentration Pathways ◽

Local Responses ◽

Ipcc Report ◽

Global Estimates

Mean sea-level is expected to rise significantly by 2100 in all scenarios, including those compatible with the objectives of the Paris Climate Agreement. Global sea level rise projections indicate devastating implications for populations, ecosystem services and biodiversity. The implications of the sea-level rise (SLR) on low-lying islands and coastal regions and communities are substantial and require deep-rooted coping measures. In the absence of adequate responses for coping, Mozambique is expected to record huge losses, with an impact on the economy and development in many sectors of its coastal regions mainly in northern Mozambique. This research aimed to perform projections on SLR in Mozambique, and to understand its role and implications on the north coast of the country. SLR was estimated through the analysis of model outputs that support the global estimates of the fifth IPCC report near the Mozambican coast, for each of the four representative concentration pathways (RCPs) scenarios. Regional coastline retreat and coastal erosion were estimated through the results of global sandy coastlines projections developed by Vousdoukas. Mean sea-level rise projections indicate that regional estimates for the Mozambican coast are relative higher than global estimates (~0.05 m) for all representative concentration pathways (RCPs). Yet, we highlight significant differences in sea-level rises of 0.5 m, 0.7 m or 1.0 m by 2100 compared to the global mean. It is expected that with the increase in the mean sea level in the northern part of the Mozambican coast, erosive effects will increase, as well as the retreat of the coastline until 2100. With this, the tourism sector, settlements, ecosystem services and local populations are expected to be significantly affected by 2050, with increased threats in 2100 (RCP4.5, RCP8.5). Local responses for coping are proposed and properly discussed for the RCP4.5 and RCP8.5 scenarios through 2100.

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