Institute of Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia.
Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France.
J Phycol. 2024 Feb;60(1):4-14. doi: 10.1111/jpy.13405. Epub 2023 Nov 9.
To limit global warming below 2°C by 2100, we must drastically reduce greenhouse gas emissions and additionally remove ~100-900 Gt CO from the atmosphere (carbon dioxide removal, CDR) to compensate for unavoidable emissions. Seaweeds (marine macroalgae) naturally grow in coastal regions worldwide where they are crucial for primary production and carbon cycling. They are being considered as a biological method for CDR and for use in carbon trading schemes as offsets. To use seaweeds in carbon trading schemes requires verification that seaweed photosynthesis that fixes CO into organic carbon results in CDR, along with the safe and secure storage of the carbon removed from the atmosphere for more than 100 years (sequestration). There is much ongoing research into the magnitude of seaweed carbon storage pools (e.g., as living biomass and as particulate and dissolved organic carbon in sediments and the deep ocean), but these pools do not equate to CDR unless the amount of CO removed from the atmosphere as a result of seaweed primary production can be quantified and verified. The draw-down of atmospheric CO into seawater is via air-sea CO equilibrium, which operates on time scales of weeks to years depending upon the ecosystem considered. Here, we explain why quantifying air-sea CO equilibrium and linking this process to seaweed carbon storage pools is the critical step needed to verify CDR by discrete seaweed beds and nearshore and open ocean aquaculture systems prior to their use in carbon trading.
为了在 2100 年前将全球变暖限制在 2°C 以下，我们必须大幅减少温室气体排放，并额外从大气中去除约 100-900 吉吨 CO（二氧化碳去除，CDR）以补偿不可避免的排放。海藻（海洋大型藻类）自然生长在全球沿海地区，它们对初级生产和碳循环至关重要。它们被认为是 CDR 的一种生物方法，并作为抵消措施用于碳交易计划。要在碳交易计划中使用海藻，需要验证将 CO 固定为有机碳的海藻光合作用会导致 CDR，以及从大气中去除的碳在 100 多年（隔离）内安全可靠地储存。目前正在进行大量研究来确定海藻碳储存池的规模（例如，作为活生物质以及沉积物和深海中的颗粒态和溶解态有机碳），但除非可以量化和验证由于海藻初级生产而从大气中去除的 CO 量，否则这些储存池并不等同于 CDR。大气 CO 被拉到海水中是通过空气-海洋 CO 平衡来实现的，这一过程的作用时间范围从几周到几年不等，具体取决于所考虑的生态系统。在这里，我们解释了为什么量化空气-海洋 CO 平衡并将这一过程与海藻碳储存池联系起来是在将离散海藻床和近岸及开阔海域水产养殖系统用于碳交易之前验证 CDR 的关键步骤。
