The Mediterranean region has been shown to be particularly exposed to climate change, with observed trends that are more pronounced than the global tendency. In forecast studies based on a RCP 8.5 scenario, there seems to be a consensus that, along with an increase in temperature and salinity over the next century, a reduction in the intensity of deep-water formation and a shallowing of the mixed layer [especially in the North-Western Mediterranean Sea (MS)] are expected. By contrast, only a few studies have investigated the effects of climate change on the biogeochemistry of the MS using a 3D physical/biogeochemical model. In this study, our aim was to explore the impact of the variations in hydrodynamic forcing induced by climate change on the biogeochemistry of the MS over the next century. For this purpose, high-resolution simulations under the RCP 8.5 emission scenario have been run using the regional climate system model CNRM-RCSM4 including the NEMO-MED8 marine component, coupled (off-line) with the biogeochemical model Eco3M-Med. The results of this scenario first highlight that most of the changes in the biogeochemistry of the MS will occur (under the RCP 8.5 scenario) after 2050. They suggest that the MS will become increasingly oligotrophic, and therefore less and less productive (14% decrease in integrated primary production in the Western Basin and in the Eastern Basin). Significant changes would also occur in the planktonic food web, with a reduction (22% in the Western Basin and 38% in the Eastern Basin) of large phytoplankton species abundance in favor of small organisms. Organisms will also be more and more N-limited in the future since NO3 concentrations are expected to decline more than those of PO4 in the surface layer. All these changes would mainly concern the Western Basin, while the Eastern Basin would be less impacted.

中文翻译：

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在RCP 8.5区域气候情景下，气候引起的流体动力学变化对地中海生物地球化学的预测影响

地中海地区已被证明特别容易受到气候变化的影响，观察到的趋势比全球趋势更明显。在基于 RCP 8.5 情景的预测研究中，似乎有一个共识，即随着下个世纪温度和盐度的升高，深水形成强度的降低和混合层的变浅 [特别是在西北地中海 (MS)] 预计。相比之下，只有少数研究使用 3D 物理/生物地球化学模型研究了气候变化对 MS 生物地球化学的影响。在这项研究中，我们的目的是探索气候变化引起的水动力强迫变化对下个世纪 MS 生物地球化学的影响。以此目的，RCP 8.5 排放情景下的高分辨率模拟已经使用区域气候系统模型 CNRM-RCSM4 运行，包括 NEMO-MED8 海洋成分，与生物地球化学模型 Eco3M-Med 耦合（离线）。该情景的结果首先强调了 MS 生物地球化学的大部分变化将在 2050 年之后发生（在 RCP 8.5 情景下）。他们表明 MS 将变得越来越贫营养，因此生产力越来越低（减少 14%西部盆地和东部盆地的综合初级生产)。浮游食物网也将发生重大变化，大型浮游植物物种丰度减少（西部盆地 22%，东部盆地 38%），有利于小型生物。生物体在未来也将越来越受 N 限制，因为预计表层中 NO3 的浓度下降得比 PO4 的浓度下降得更多。所有这些变化将主要涉及西部盆地，而东部盆地受到的影响较小。