PDF(Pubmed)
Abstract：
Mitigating global climate change will require gigaton-scale carbon dioxide removal (CDR) as a supplement to rapid emissions reduction. The oceans cover 71% of the Earth surface and have the potential to provide much of the required CDR. However, none of the proposed marine CDR (mCDR) methods is sufficiently well understood to determine their real-world efficiency and environmental side effects. Here, we argue that using natural mCDR analogs should become the third interconnecting pillar in the mCDR assessment as they bridge the gap between numerical simulations (i.e., large scale/reduced complexity) and experimental studies (i.e., small scale/high complexity). Natural mCDR analogs occur at no cost, can provide a wealth of data to inform mCDR, and do not require legal permission or social license for their study. We propose four simple criteria to identify particularly useful analogs: 1) large scale, 2) abruptness of perturbation, 3) availability of unperturbed control sites, and 4) reoccurrence. Based on these criteria, we highlight four examples: 1) equatorial upwelling as a natural analog for artificial upwelling, 2) downstream of Kerguelen Island for ocean iron fertilization, 3) the Black and Caspian Seas for ocean alkalinity enhancement, and 4) the Great Atlantic Sargassum Belt for ocean afforestation. These natural analogs provide a reality check for experimental assessments and numerical modeling of mCDR. Ultimately, projections of mCDR efficacy and sustainability supported by observations from natural analogs will provide the real-world context for the public debate and will facilitate political decisions on mCDR implementation. We anticipate that a rigorous investigation of natural analogs will fast-forward the urgently needed assessment of mCDR.
摘要：
缓解全球气候变化将需要gigaton规模的二氧化碳去除（CDR）作为快速减排的补充。海洋覆盖了地球表面的71％，并有可能提供大量所需的CDR。然而,所提出的海洋CDR(mCDR)方法中没有一种被充分理解以确定它们的真实世界效率和环境副作用。这里,我们认为，使用天然mCDR类似物应该成为mCDR评估中的第三个互连支柱，因为它们弥合了数值模拟之间的差距(即，大规模/降低复杂性)和实验研究(即小规模/高复杂性)。天然mCDR类似物是免费的，可以提供丰富的数据通知mCDR，他们的学习不需要法律许可或社会许可。我们提出了四个简单的标准来识别特别有用的类似物：1)大规模，2)突然的扰动，3)无扰动控制地点的可用性，4）复发。基于这些标准,我们强调了四个例子:1)赤道上升流作为人工上升流的自然类似物，2)在克格伦岛下游进行海洋铁施肥，3）黑海和里海增强海洋碱度，和4)海洋造林大大西洋马尾藻带。这些天然类似物为mCDR的实验评估和数值模拟提供了现实检验。最终,在自然类似物的观察支持下，对mCDR功效和可持续性的预测将为公众辩论提供现实世界的背景，并将促进关于mCDR实施的政治决定。我们预计对天然类似物的严格研究将快速推进迫切需要的mCDR评估。
