Yamamoto Akitomo, Hajima Tomohiro, Yamazaki Dai, Noguchi Aita Maki, Ito Akinori, Kawamiya Michio
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan.
Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan.
Sci Adv. 2022 Jul;8(26):eabl9207. doi: 10.1126/sciadv.abl9207. Epub 2022 Jul 1.
Nutrient inputs from the atmosphere and rivers to the ocean are increased substantially by human activities. However, the effects of increased nutrient inputs are not included in the widely used CMIP5 Earth system models, which introduce bias into model simulations of ocean biogeochemistry. Here, using historical simulations by an Earth system model with perturbed atmospheric and riverine nutrient inputs, we show that the contribution of anthropogenic nutrient inputs to past global changes in ocean biogeochemistry is of similar magnitude to the effect of climate change. Anthropogenic nutrient inputs increase oceanic productivity and carbon uptake, offsetting climate-induced decrease and accelerating climate-driven deoxygenation in the upper ocean. Moreover, accounting for anthropogenic nutrient inputs improves the known carbon budget imbalance and model underestimation of the observed decrease in the global oxygen inventory. Considering the effects of both nutrient inputs and climate change is crucial in assessing anthropogenic impacts on ocean biogeochemistry.
人类活动大幅增加了从大气和河流到海洋的营养物质输入。然而，增加的营养物质输入的影响并未包含在广泛使用的CMIP5地球系统模型中，这给海洋生物地球化学的模型模拟带来了偏差。在此，我们使用一个对大气和河流营养物质输入进行了扰动的地球系统模型进行历史模拟，结果表明，人为营养物质输入对过去全球海洋生物地球化学变化的贡献与气候变化的影响幅度相当。人为营养物质输入增加了海洋生产力和碳吸收，抵消了气候导致的海洋上层生产力下降，并加速了气候驱动的海洋上层脱氧过程。此外，考虑人为营养物质输入改善了已知的碳收支不平衡问题，以及模型对全球氧气储量观测到的减少量的低估。在评估人为活动对海洋生物地球化学的影响时，同时考虑营养物质输入和气候变化的影响至关重要。
