Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services
Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services
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DOI：
10.3389/fclim.2021.738224
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发表时间：
2021-11
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影响因子：
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通讯作者：
A. Tagliabue;L. Kwiatkowski;L. Bopp;M. Butenschön;W. Cheung;M. Lengaigne;J. Vialard
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作者：
A. Tagliabue;L. Kwiatkowski;L. Bopp;M. Butenschön;W. Cheung;M. Lengaigne;J. Vialard
海洋净初级生产力（NPP）是海洋浮游植物固定CO2的结果，催化有机物质和能量向海洋生态系统的转移，支持大多数海洋食物网和渔业生产，并刺激海洋碳固存。因此，作为第五和第六次耦合模式相互比较项目（CMIP 5和CMIP 6）工作的一部分，地球系统模型实验量化了海洋NPP对气候变化的响应，预计将改变关键的生态系统服务。尽管自CMIP 5以来，模式间变异性有所减少，但由于不完全理解和观测约束不足，CMIP 6模式的海洋组成部分在当代NPP的幅度和空间分布方面存在大约2倍的差异。对NPP绝对值变化的预测显示，CMIP 6存在很大的不确定性，尤其是在北大西洋和印度洋-太平洋区域，后者解释了模型间不确定性的三分之二以上。虽然印度洋-太平洋地区此前已被确定为气候对生物多样性和渔业影响的热点地区，但NPP预测的模型间变异性增加进一步加剧了依赖海洋的人类社区气候风险的不确定性。区域尺度NPP变化的不确定性驱动因素整合了不同的物理和地球化学因素，需要在未来的研究中进行更有针对性的机制评估。在全球范围内，自CMIP 5以来，NPP预测变化的模型间不确定性有所增加，这加剧了与相关生态系统服务管理相关的挑战。值得注意的是，尽管历史时期区域NPP率的不确定性降低，但CMIP 6预测的NPP变化的区域不确定性增加。改善对海洋净初级生产力大小的限制及其空间变异性的机械驱动因素将提高对未来变化的信心。CMIP 6模式集合不太可能对NPP的完全不确定性进行采样，包括额外的机械现实主义可能会在未来进一步扩大预测，特别是在区域尺度上。这对评估生态系统影响具有重要影响。最终，我们需要一个综合的机制框架，考虑NPP和海洋生态系统如何应对气候变化的影响，以及其他非气候驱动因素。
Ocean net primary production (NPP) results from CO2 fixation by marine phytoplankton, catalysing the transfer of organic matter and energy to marine ecosystems, supporting most marine food webs, and fisheries production as well as stimulating ocean carbon sequestration. Thus, alterations to ocean NPP in response to climate change, as quantified by Earth system model experiments conducted as part of the 5th and 6th Coupled Model Intercomparison Project (CMIP5 and CMIP6) efforts, are expected to alter key ecosystem services. Despite reductions in inter-model variability since CMIP5, the ocean components of CMIP6 models disagree roughly 2-fold in the magnitude and spatial distribution of NPP in the contemporary era, due to incomplete understanding and insufficient observational constraints. Projections of NPP change in absolute terms show large uncertainty in CMIP6, most notably in the North Atlantic and the Indo-Pacific regions, with the latter explaining over two-thirds of the total inter-model uncertainty. While the Indo-Pacific has previously been identified as a hotspot for climate impacts on biodiversity and fisheries, the increased inter-model variability of NPP projections further exacerbates the uncertainties of climate risks on ocean-dependent human communities. Drivers of uncertainty in NPP changes at regional scales integrate different physical and biogeochemical factors that require more targeted mechanistic assessment in future studies. Globally, inter-model uncertainty in the projected changes in NPP has increased since CMIP5, which amplifies the challenges associated with the management of associated ecosystem services. Notably, this increased regional uncertainty in the projected NPP change in CMIP6 has occurred despite reduced uncertainty in the regional rates of NPP for historical period. Improved constraints on the magnitude of ocean NPP and the mechanistic drivers of its spatial variability would improve confidence in future changes. It is unlikely that the CMIP6 model ensemble samples the complete uncertainty in NPP, with the inclusion of additional mechanistic realism likely to widen projections further in the future, especially at regional scales. This has important consequences for assessing ecosystem impacts. Ultimately, we need an integrated mechanistic framework that considers how NPP and marine ecosystems respond to impacts of not only climate change, but also the additional non-climate drivers.