Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method
Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method
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DOI：
10.5194/bg-10-1799-2013
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发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Le Quere, C.
中科院分区：
文献类型：
--
作者：
Andrews, O. D.;Bindoff, N. L.;Le Quere, C.
过去 50 年来，所有主要海洋盆地均观察到海洋缺氧现象。尽管这一信号与人为气候变化预期的氧气变化基本一致，但相对于自然内部变率，外部强迫对近期脱氧趋势的贡献尚未确定。在这里，我们使用两个地球系统模型（MPI-ESM-LR 和 HadGEM2-ES）的模拟进行正式的最佳指纹分析，以调查外部强迫是否对 1970 年和 1992 年之间观测到的溶解氧浓度 ([O-2]) 变化产生了可检测的影响。我们以 90% 的置信度检测对外部强迫的响应，并发现观察到的 [O-2] 变化与模型模拟的内部变化不一致。对于两个模型中 [O-2] 变化的深度平均 (1-D) 地带平均模式，该结果在全球海洋中是稳健的。 MPI-ESMLR 模型的进一步分析显示，全球和太平洋的深度分辨 (2-D) 纬向平均 [O-2] 变化具有类似的阳性检测结果。观测到的大西洋氧气变化与自然内部变化无法区分。两个模型的模拟始终低估了响应外力的历史 [O-2] 变化幅度，这表明模型对未来海洋脱氧的预测也可能被低估。
Ocean deoxygenation has been observed in all major ocean basins over the past 50 yr. Although this signal is largely consistent with oxygen changes expected from anthropogenic climate change, the contribution of external forcing to recent deoxygenation trends relative to natural internal variability is yet to be established. Here we conduct a formal optimal fingerprinting analysis to investigate if external forcing has had a detectable influence on observed dissolved oxygen concentration ([O-2]) changes between similar to 1970 and similar to 1992 using simulations from two Earth System Models (MPI-ESM-LR and HadGEM2-ES). We detect a response to external forcing at a 90% confidence level and find that observed [O-2] changes are inconsistent with internal variability as simulated by models. This result is robust in the global ocean for depth-averaged (1-D) zonal mean patterns of [O-2] change in both models. Further analysis with the MPI-ESMLR model shows similar positive detection results for depth-resolved (2-D) zonal mean [O-2] changes globally and for the Pacific Ocean individually. Observed oxygen changes in the Atlantic Ocean are indistinguishable from natural internal variability. Simulations from both models consistently underestimate the amplitude of historical [O-2] changes in response to external forcing, suggesting that model projections for future ocean deoxygenation may also be underestimated.