Pacific Coastal and Marine Science Center, U.S. Geological Survey, Santa Cruz, CA, 95060, USA.
Marine Science Institute, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
Sci Rep. 2021 Jul 30;11(1):15560. doi: 10.1038/s41598-021-94942-7.
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.
随着下个世纪气候的演变，海平面上升（SLR）和风暴的相互作用，再加上限制发展和基础设施，将使海洋与陆地边缘的物理、生态和人类系统承受更大的压力。这些具有重要价值的沿海系统中的许多系统可能会达到“临界点”，在这个点上，灾害暴露会大大增加，并威胁到社区、基础设施和生态系统目前的形式、功能和生存能力。确定这些临界点的时间和性质对于有效的气候适应规划至关重要。在这里，我们提供了一个来自美国加利福尼亚州圣巴巴拉的多学科案例研究，以确定各种沿海系统与气候变化相关的临界点。本研究综合了气候、海洋水位、海滩和悬崖演化以及两个软泥沙生态系统（沙滩和潮汐湿地）的数值和统计模型。我们发现，海滩和湿地的临界点可能在海平面上升 0.25 米或更少（约 2050 年）时达到，随后会有超过 50%的栖息地损失，这将降低整体生物多样性和生态系统功能。相比之下，该地区五个社区预计到海平面上升 0.75 米以上才会出现日常洪水泛滥和 1.5 米以上才会出现风暴驱动洪水泛滥的最大社会经济暴露变化（约 2100 年或以后）。与社区总数相比，这些变化不那么剧烈，并且由于社区的适应能力，它们不符合临界点的标准。尽管如此，自然和人类建造的系统是相互关联的，因此自然系统功能的丧失可能会对居民的生活质量产生负面影响，并扰乱当地经济，从而在基础设施直接受到洪水影响之前，就会产生间接的社会经济影响。
