School of Environmental Sciences, University of Liverpool, Liverpool, UK.
Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA.
Glob Chang Biol. 2023 Sep;29(18):5250-5260. doi: 10.1111/gcb.16854. Epub 2023 Jul 6.
Climate change scenarios suggest that large-scale carbon dioxide removal (CDR) will be required to maintain global warming below 2°C, leading to renewed attention on ocean iron fertilization (OIF). Previous OIF modelling has found that while carbon export increases, nutrient transport to lower latitude ecosystems declines, resulting in a modest impact on atmospheric CO . However, the interaction of these CDR responses with ongoing climate change is unknown. Here, we combine global ocean biogeochemistry and ecosystem models to show that, while stimulating carbon sequestration, OIF may amplify climate-induced declines in tropical ocean productivity and ecosystem biomass under a high-emission scenario, with very limited potential atmospheric CO drawdown. The 'biogeochemical fingerprint' of climate change, that leads to depletion of upper ocean major nutrients due to upper ocean stratification, is reinforced by OIF due to greater major nutrient consumption. Our simulations show that reductions in upper trophic level animal biomass in tropical regions due to climate change would be exacerbated by OIF within ~20 years, especially in coastal exclusive economic zones (EEZs), with potential implications for fisheries that underpin the livelihoods and economies of coastal communities. Any fertilization-based CDR should therefore consider its interaction with ongoing climate-driven changes and the ensuing ecosystem impacts in national EEZs.
气候变化情景表明，为了将全球变暖控制在 2°C 以下，需要大规模的二氧化碳去除（CDR），这导致人们重新关注海洋铁施肥（OIF）。先前的 OIF 建模研究发现，尽管碳的输出增加了，但营养物质向低纬度生态系统的输送减少了，这导致大气 CO2 的含量略有下降。然而，这些 CDR 反应与正在发生的气候变化之间的相互作用尚不清楚。在这里，我们结合全球海洋生物地球化学和生态系统模型，表明尽管 OIF 刺激了碳的封存，但在高排放情景下，它可能会放大气候引起的热带海洋生产力和生态系统生物量的下降，而对大气 CO2 的吸收量非常有限。由于海洋上分层导致上层海洋主要营养物质枯竭的“生物地球化学指纹”，由于 OIF 而进一步加剧，因为 OIF 消耗了更多的主要营养物质。我们的模拟表明，由于气候变化导致热带地区上层营养级动物生物量减少，如果再加上 OIF，这种情况将在 20 年内加剧，特别是在沿海专属经济区（EEZ），这可能对渔业产生影响，而渔业是沿海社区生计和经济的基础。因此，任何基于施肥的 CDR 都应考虑其与正在发生的气候驱动变化的相互作用，以及由此对国家 EEZ 生态系统产生的影响。
