Resilient coasts: optimising co-benefit solutions (Co-Opt)

海洋和社会在海岸的相互作用最为强烈，那里的社区既受益于海洋环境，也受到海洋环境的威胁。2017年，在英国政府的风险登记册上，沿海洪水是仅次于大流行性流感的第二大风险。仅在英格兰，就有180多万户家庭面临海岸洪水和侵蚀的风险。极端事件已经对海岸产生了非常重大的影响，2013/14年冬季沿海洪水造成的损失超过5亿英镑，平均每年的直接经济影响超过2.6亿英镑。沿海灾害将在下个世纪增加，主要是由于不可避免的海平面上升。与此同时，英国承诺到2050年实现净零碳排放。因此，必须确保对英国海岸进行管理，以使海岸保护能够适应未来的气候，并实现净零排放的目标。通过在目前计划的所有地点维持坚硬的“灰色”防御来保护海岸不太可能具有成本效益。因此，可持续的沿海管理和适应将需要更广泛的行动，并更多地使用与自然相结合的、多功能的、可以带来额外效益的软“绿色”解决方案。这样的例子已经存在，包括有管理的重新调整，海岸栖息地的恢复，以及超大的沙子营养。然而，对绿色解决方案的吸收仍然参差不齐。根据气候变化委员会的数据，实现有管理的调整的速度是2030年既定目标的五倍。原因是复杂的，跨越了整个人-环境系统。基于自然的解决方案往往缺乏公众舆论的支持和社会阻力。尽管消除了对硬防御的长期承诺，但由于前期成本高、难以评估所提供的多种协同效益以及未来环境和社会经济预测固有的不确定性，绿色方法的经济理由仍然不确定。用于支持当前海岸管理和政策制定的框架（例如海岸线管理计划）没有提供全面和一致的方法来解决这些问题。其后果是这些政策措施的有效性降低。因此，实现英国海岸的可持续管理将需要新的框架，包括整个复杂的人类环境系统，并提供全面的科学基础，以确定不同的价值系统如何与决策相互作用，气候变化将如何影响沿海生态系统服务，以及决策支持工具如何结合多种不确定性。Co-Opt将提供一个新的综合和跨学科的基于系统的框架，将有效地支持沿海和海岸线管理从硬“灰色”防御到软“绿色”解决方案的必要过渡。该框架将首次结合复杂的沿海社会生态系统的概念表示、气候变化下沿海生态系统服务的定量评估，以及社会观念和价值观如何影响前两个要素的特征。我们的新框架将与国家、地区和地方利益相关者合作，在英国进行四个案例研究。这将提供一个可扩展和适应性的解决方案，以支持沿海管理和政策制定。Co-Opt是与项目合作伙伴共同设计的，这些合作伙伴对沿海和海岸线管理的实施和交付至关重要（例如环境署、威尔士自然资源、NatureScot、沿海组织），并将满足他们的具体需求，包括制定彻底的成本效益分析和在首选政策发生变化时为行动计划提出建议。通过支持对复杂的沿海人-环境系统进行更综合和跨学科的表征，Co-Opt将进一步有利于广泛的沿海科学基础。

Sea and society interact most strongly at the coast where communities both benefit from and are threatened by the marine environment. Coastal flooding was the second highest risk after pandemic flu on the UK government's risk register in 2017. Over 1.8 million homes are at risk of coastal flooding and erosion in England alone. Extreme events already have very significant impacts at the coast, with the damage due to coastal flooding during the winter 2013/14 in excess of £500 million, and direct economic impacts exceeding £260 million per year on average. Coastal hazards will be increasing over the next century primarily driven by unavoidable sea level rise. At the same time, the UK is committed to reach net zero carbon emissions by 2050. It is therefore essential to ensure that UK coasts are managed so that coastal protection is resilient to future climate and the net zero ambition is achieved. Protecting the coast by maintaining hard 'grey' defences in all locations currently planned is unlikely to be cost-effective. Sustainable coastal management and adaptation will therefore require a broader range of actions, and greater use of softer 'green' solutions that work with nature, are multifunctional, and can deliver additional benefits.Examples already exist and include managed realignment, restoration of coastal habitats, and sand mega-nourishments. However, the uptake of green solutions remains patchy. According to the Committee on Climate Change, the uptake of managed realignment is five times too slow to meet the stated 2030 target. Reasons are complex and span the whole human-environment system. Nature-based solutions often lack support from public opinion and meet social resistance. Despite removing long-term commitment to hard defences, the economic justification for green approaches remains uncertain due to high upfront costs, difficulty in valuing the multiple co-benefits offered, and uncertainties inherent to future environmental and socio-economic projections. The frameworks used to support present day coastal management and policy making (e.g. Shoreline Management Plans) do not provide comprehensive and consistent approaches to resolve these issues. Consequences are that the effectiveness of these policy approaches is reduced. Delivering sustainable management of UK coasts will therefore require new frameworks that embrace the whole complex human-environment system and provide thorough scientific underpinning to determine how different value systems interact with decision making, how climate change will impact coastal ecosystem services, and how decision support tools can combine multiple uncertainties.Co-Opt will deliver a new integrated and interdisciplinary system-based framework that will effectively support the required transition from hard 'grey' defences to softer 'green' solutions in coastal and shoreline management. This framework will combine for the first time a conceptual representation of the complex coastal socio-ecological system, quantitative valuation of coastal ecosystem services under a changing climate, and the characterisation of how social perceptions and values influence both previous elements. Our new framework will be demonstrated for four case studies in the UK in collaboration with national, regional, and local stakeholders. This will provide a scalable and adaptive solution to support coastal management and policy development. Co-Opt has been co-designed with project partners essential to the implementation and delivery of coastal and shoreline management (e.g. Environment Agency, Natural Resources Wales, NatureScot, coastal groups) and will address their specific needs including development of thorough cost-benefit analyses and recommendations for action plans when preferred policy changes. Co-Opt will further benefit the broad coastal science base by supporting more integrated and interdisciplinary characterisation of the complex coastal human-environment system.