Given the importance of coastal upwelling systems to ocean productivity, fisheries, and biogeochemical cycles, their response to climate change is of great interest. However, there is no consensus on future productivity changes in these systems, which may be controlled by multiple drivers including wind-driven and geostrophic transport, stratification, and source water properties. Here we use an ensemble of regional ocean projections and recently developed upwelling indices for the California Current System to disentangle these sometimes-competing influences. Some changes are consistent among models (e.g., decreased mixed layer depth), while for others there is a lack of agreement even on the direction of future change (e.g., nitrate concentration in upwelled waters). Despite models' diverging projections of productivity changes, they agree that those changes are predominantly driven by subsurface nitrate concentrations, not by upwelling strength. Our results highlight the need for more attention to processes governing subsurface nutrient changes, not just upwelling strength.

中文翻译：

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将上升流动力学和地下营养物与加州海流系统中预计的生产力变化联系起来

鉴于沿海上升流系统对海洋生产力、渔业和生物地球化学循环的重要性，它们对气候变化的响应引起了人们的极大兴趣。然而，对于这些系统未来生产力的变化尚未达成共识，这可能受到多种驱动因素的控制，包括风驱动和地转输送、分层和水源水特性。在这里，我们使用区域海洋预测和最近开发的加州洋流系统上升流指数的集合来理清这些有时相互竞争的影响。一些变化在模型之间是一致的（例如，混合层深度减少），而对于其他变化，甚至在未来变化的方向上也缺乏共识（例如，上升水域中的硝酸盐浓度）。尽管模型对生产力变化的预测存在分歧，但他们一致认为这些变化主要是由地下硝酸盐浓度驱动的，而不是由上升流强度驱动的。我们的结果强调需要更多地关注控制地下营养物变化的过程，而不仅仅是上升流强度。