Global Ocean Conservation Priorities – Carbon Protection

Numerical ranking of the global ocean to prioritize conservation actions aimed at safeguarding carbon stored in sediments. The conservation action being prioritized is highly protected Marine Protected Areas (MPAs). Most important pixels are ranked higher (1) and least important pixels are ranked lower (0). Pixels ranked between 0.95-1, correspond to the most important 5% of the ocean. Pixels ranked between 0.9-1, correspond to the most important 10% of the ocean, and so on. Existing highly protected MPAs represent the starting condition of the analyses and are placed at the top of the ranking. Variable mapped: Global priority ranking for safeguarding carbon Data Projection: Mollweide Equal Area Mosaic Projection: Mollweide Equal Area Extent: Global Cell Size: 50km Source Type: Thematic Source: National Geographic Society Publication: Sala, Enric, Juan Mayorga, Darcy Bradley, Reniel B. Cabral, Trisha B. Atwood, Arnaud Auber, William Cheung, et al. “Protecting the Global Ocean for Biodiversity, Food and Climate.” Nature, March 17, 2021. https://doi.org/10.1038/s41586-021-03371-z. We define the carbon benefits of a given set of MPAs as the change in carbon content in marine sediments relative to business as usual. We model this benefit by combining a global map of the carbon stored in the first meter of marine sediments, with the global footprint of bottom trawling detected with Global Fishing Watch (2015-2019, 1 km2 resolution), and relevant oceanographic variables that are known to affect carbon loss including: Sediment resettlement ratio – the fraction of disturbed sediment that resettles in the same 1km2 pixel and therefore is trackable by our model. Labile carbon ratio – proportion of carbon that is labile and thus more prone to remineralization after a disturbance. The labile fraction was estimated as a function of the type of sediment. First-order degradation constant—The first-order degradation rate constants were assigned as a function of oceanic region, and were estimated from ranges of values presented in the literature for oxic sediments本数据集为全球海洋的数值排名，用于优先排序旨在保护沉积物中储存碳的保护行动，优先实施保护的对象为严格保护海洋保护区（Marine Protected Areas，MPAs）。排名越接近1的像元代表对应海域重要性越高，排名越接近0则代表海域重要性越低。数值处于0.95-1区间的像元，对应全球海洋中最重要的5%海域；数值处于0.9-1区间的像元，对应全球海洋中最重要的10%海域，以此类推。现有严格保护MPAs作为分析的初始条件，位列排名首位。 本次映射的变量为：用于保护海洋碳储的全球优先级排名。 数据投影：摩尔魏特等面积投影（Mollweide Equal Area） 覆盖范围：全球 像元分辨率：50千米 数据来源类型：专题数据 数据来源：国家地理学会（National Geographic Society） 相关文献：Sala, Enric、Juan Mayorga、Darcy Bradley等学者于2021年3月17日发表在《自然》（Nature）的论文"Protecting the Global Ocean for Biodiversity, Food and Climate."，DOI: 10.1038/s41586-021-03371-z。 本研究将给定MPAs集合的碳效益定义为：相较于常规发展情景，海洋沉积物中碳含量的变化量。我们通过以下方式对该效益进行建模：结合海洋表层1米沉积物碳储量的全球分布图、由全球捕捞观察平台（Global Fishing Watch）于2015-2019年监测得到的全球底拖网捕捞足迹（分辨率为1平方千米），以及已知会影响碳损失的相关海洋学变量，具体包括： 1. 沉积物再沉降比例：受扰动沉积物在同一1平方千米像元内重新沉降的比例，因此可被本模型追踪； 2. 活性碳比例：沉积物中活性碳的占比，这类碳在受到扰动后更易发生再矿化。活性碳占比根据沉积物类型进行估算； 3. 一级降解常数：一级降解速率常数根据海洋区域进行赋值，其取值范围基于已发表文献中针对有氧沉积物的相关研究结果估算得到。