Abstract

Finding ways to keep global warming under 1.5 degrees Celsius is urgent and will need a portfolio of solutions. Seaweeds are marine photosynthetic organisms that humans harvest either from the wild or farm, to be used in many applications and providing various ecosystem services. Large scale farming of seaweeds for absorbing carbon has lately been promoted as a climate “fix”. The major shortcomings of this argument relate to the idea that a carbon sink function should exist through carbon accumulation in seaweed biomass simultaneously as seaweeds are consumed as food by humans, fed to animals, or used in many alternative applications. This carbon instead enters the fast carbon cycle and does not provide any “carbon sink” function. Radical suggestions of intentionally transfer of farmed seaweeds to the deep-sea to accomplish a longer removal are highly questionable from feasibility, economic, ecosystem effects and ethical resource use perspectives. Development of “ocean forests” for carbon capturing through farming should not be compared to forests on land as these provide carbon removal from the atmosphere at sufficiently long time scales to be qualified as carbon sequestration - thus making a difference related to reducing atmospheric greenhouse gas concentrations. Seaweeds can, however, play a role in reducing greenhouse gas emissions from the overall food system through carbon offset - i.e. if replacing food, feed, and/or materials that have larger carbon footprints. The fate/cycling of carbon as particulate and dissolved matter from both farmed and wild seaweeds, are however not fully understood, especially with respect to pathways and time scales relevant for carbon removal/storage. Another potential pathway for their role in decarbonization may be through reducing enteric methane emissions from ruminants and also through bioenergy production. More research is, however, needed for understanding the contributions from such interventions. Presenting seaweed farming as a quick fix for the climate risks facilitating misdirected investments (for carbon abatement solutions) and reducing demand for specific research and technological development that will be needed for increasing our understanding about seaweeds’ contribution to food/feed systems and additional sustainability services and benefits.

Supplemental data for this article is available online at https://doi.org/10.1080/23308249.2022.2048792 .

摘要

寻找将全球变暖控制在 1.5 摄氏度以下的方法刻不容缓，需要采取一系列解决方案。海藻是海洋光合生物，人类从野外或农场收获，用于许多应用并提供各种生态系统服务。用于吸收碳的大规模海藻养殖最近被提倡为气候“修复”。这一论点的主要缺点与以下观点有关：碳汇功能应该通过海藻生物量中的碳积累而存在，同时海藻被人类作为食物消费、喂养动物或用于许多替代应用。这种碳反而进入快速碳循环，不提供任何“碳汇”功能。从可行性、经济、生态系统影响和道德资源利用的角度来看，有意将养殖海藻转移到深海以实现更长时间清除的激进建议是非常值得怀疑的。通过农业捕获碳的“海洋森林”的开发不应与陆地上的森林相比较，因为这些森林可以在足够长的时间范围内从大气中去除碳，从而达到碳封存的资格，从而在降低大气温室气体浓度方面产生影响。然而，海藻可以通过碳抵消在减少整个食品系统的温室气体排放方面发挥作用，即替代具有较大碳足迹的食品、饲料和/或材料。养殖和野生海藻中碳作为颗粒物和溶解物的命运/循环，然而，尚未完全理解，特别是在与碳去除/储存相关的途径和时间尺度方面。它们在脱碳中发挥作用的另一个潜在途径可能是减少反刍动物的肠道甲烷排放以及生物能源生产。然而，需要更多的研究来了解此类干预措施的贡献。将海藻养殖作为应对气候风险的快速解决方案，会促进错误投资（碳减排解决方案），并减少对特定研究和技术开发的需求，而这些需求是加深我们对海藻对食品/饲料系统和其他可持续发展服务的贡献的了解所必需的和好处。它们在脱碳中发挥作用的另一个潜在途径可能是减少反刍动物的肠道甲烷排放以及生物能源生产。然而，需要更多的研究来了解此类干预措施的贡献。将海藻养殖作为应对气候风险的快速解决方案，会促进错误投资（碳减排解决方案），并减少对特定研究和技术开发的需求，而这些需求是加深我们对海藻对食品/饲料系统和其他可持续发展服务的贡献的了解所必需的和好处。它们在脱碳中发挥作用的另一个潜在途径可能是减少反刍动物的肠道甲烷排放以及生物能源生产。然而，需要更多的研究来了解此类干预措施的贡献。将海藻养殖作为应对气候风险的快速解决方案，会促进错误投资（碳减排解决方案），并减少对特定研究和技术开发的需求，而这些需求是加深我们对海藻对食品/饲料系统和其他可持续发展服务的贡献的了解所必需的和好处。了解此类干预措施的贡献是必要的。将海藻养殖作为应对气候风险的快速解决方案，会促进错误投资（碳减排解决方案），并减少对特定研究和技术开发的需求，而这些需求是加深我们对海藻对食品/饲料系统和其他可持续发展服务的贡献的了解所必需的和好处。了解此类干预措施的贡献是必要的。将海藻养殖作为应对气候风险的快速解决方案，会促进错误投资（碳减排解决方案），并减少对特定研究和技术开发的需求，而这些需求是加深我们对海藻对食品/饲料系统和其他可持续发展服务的贡献的了解所必需的和好处。

本文的补充数据可在线获取：https://doi.org/10.1080/23308249.2022.2048792。