Multiple climate change-driven tipping points for coastal systems

Abstract

As the climate evolves over the next century, the interaction of accelerating sea level rise (SLR) and storms, combined with confining development and infrastructure, will place greater stresses on physical, ecological, and human systems along the ocean-land margin. Many of these valued coastal systems could reach “tipping points,” at which hazard exposure substantially increases and threatens the present-day form, function, and viability of communities, infrastructure, and ecosystems. Determining the timing and nature of these tipping points is essential for effective climate adaptation planning. Here we present a multidisciplinary case study from Santa Barbara, California (USA), to identify potential climate change-related tipping points for various coastal systems. This study integrates numerical and statistical models of the climate, ocean water levels, beach and cliff evolution, and two soft sediment ecosystems, sandy beaches and tidal wetlands. We find that tipping points for beaches and wetlands could be reached with just 0.25 m or less of SLR (~ 2050), with > 50% subsequent habitat loss that would degrade overall biodiversity and ecosystem function. In contrast, the largest projected changes in socioeconomic exposure to flooding for five communities in this region are not anticipated until SLR exceeds 0.75 m for daily flooding and 1.5 m for storm-driven flooding (~ 2100 or later). These changes are less acute relative to community totals and do not qualify as tipping points given the adaptive capacity of communities. Nonetheless, the natural and human built systems are interconnected such that the loss of natural system function could negatively impact the quality of life of residents and disrupt the local economy, resulting in indirect socioeconomic impacts long before built infrastructure is directly impacted by flooding.

Dynamic restoration and the impact of native versus invasive vegetation on coastal foredune morphodynamics, Lanphere Dunes, California, USA

“…Estimated trends and modelled sea level rise (between 0.9 and 1.8 m) have shown that 4.2-13.1 million US citizens could be at risk of inundation (Hauer et al, 2016). Recent assessments (Barnard et al, 2019(Barnard et al, , 2021 suggest that many coastal regions could be reaching a 'tipping point' with regard to coastal flooding hazard, biodiversity, and ecosystem function if current trends in sea level rise hold constant or accelerate and steps to mitigate these trends are not taken.…”

Exploring urban growth–climate change–flood risk nexus in fast growing cities

“…Therefore, the urban growth-climate change-flood risk nexus in these urban hubs must be managed. Also, since most urban development occurs along coasts in the Arabian Gulf, climate change puts these hubs at additional risk of rising sea levels 1 , 36 . Hence, unless wise and proactive flood and sea-level rise mitigation and adaptation actions are taken, the environmental cost of urban growth and climate change will exacerbate, and tipping points may be reached in the region’s physical systems.…”

Human‐in‐the‐Loop Segmentation of Earth Surface Imagery

“…The imagery is from North and South Carolina taken after Hurricane Florence (2018). Post storm imagery can be used to monitor the effects of hurricanes on coastal communities (Chen et al., 2018) and ecosystems (Barnard et al., 2021) and coastal change (Goldstein et al., 2020). The images are labeled using the following classes: (a) water, (b) sand, (c) vegetated surface, and (d) development.…”