On the need of considering the uncertainty cascade for decision making on climate-change adaptation to coastal erosion

Climate change is posing growing risks to coastal areas exacerbating the problems these systems already face. One of these problems is coastal erosion, which happens at two different time scales. On one hand, mean sea-level rise leads to the chronic loss of beach surface; on the other, the combined effect of waves, storm surges and tides causes episodic erosion, which due to this increase in mean sea level will become more frequent. In light of this, while some systems will be able to undergo a landward retreat, others will suffer from coastal squeeze, which occurs when an eroding coast approaches seawalls or resistant natural cliffs, leading to adverse impacts to both environment and society. Coastal erosion risks need to be addressed with adaptation, and this is particularly challenged by the high uncertainty in climate change-related erosion forcing conditions. Expanding scientific knowledge of uncertainty treatment in climate-change coastal erosion projections is thus key to effective decision making (Toimil et al., 2021a). Here, we show progress on decomposition, factorisation, attribution, and visualisation of the uncertainty sources involved in shoreline change projections, which arise from climate-change scenarios, climate models, and erosion models, and cascade through the complete impact modelling process. This uncertainty accumulates in coastal erosion estimates, is further inherited by erosion risks and can highly influence adaptation planning (Toimil et al., 2021b).

Toimil A, Camus P, Losada IJ, Álvarez-Cuesta M (2021a) Visualising the uncertainty cascade in multi-ensemble probabilistic coastal erosion projections. Front. Mar. Sci. 8:683535.

Toimil A, Losada IJ, Hinkel J, Nicholls RJ (2021b) Using quantitative dynamic adaptive policy pathways to manage climate change-induced coastal erosion. Clim. Risk Manag. 33, 100342.