The role of ocean dynamics in king penguin range estimation
The role of ocean dynamics in king penguin range estimation
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海洋动力学在王企鹅分布范围估计中的作用
DOI：
10.1038/s41558-018-0388-2
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发表时间：
2019
影响因子：
30.7
通讯作者：
E. Young
中科院分区：
文献类型：
--
作者：
A. Meijers;M. Meredith;E. Murphy;D. Chambers;M. Belchier;E. Young
1英国南极调查局，英国剑桥。2南佛罗里达大学海洋科学学院，美国佛罗里达州圣彼得堡。* 电子邮件：andmei@bas.ac.uk在最近的一篇文章中，Cristofari等人1讨论了南极极锋的运动对历史上王企鹅种群的影响，并根据潜在的气候变化情景对未来进行了预测。他们预测，世界上70%的繁殖人口将受到严重影响，因为极地前沿的营养丰富的上升流和高生产力，将向极地移动，超出许多企鹅殖民地的觅食范围。然而，我们在这里强调，对所用模型的详细分析并不支持极锋未来位置向极方向移动的预测，最近的分析表明，在过去几十年中没有发生这种移动的证据。Cristofari等人1使用恒定海表面温度（SST）等温线的位置作为极锋位置的代表，从而确定觅食范围。在短的时间尺度上，这个代理与实际的前沿一致，被确定为深入的强水平属性梯度和高流速，并与企鹅觅食范围2相关。然而，在未来的气候强迫情景下，SST和深锋的位置（及其相关的营养梯度，强流和上升流）由于强烈的表面变暖而变得脱钩，从而质疑SST和觅食范围之间的经验相关性的持续有效性。在Cristofari等人使用的耦合模型相互比较项目第5阶段（CMIP 5）模型集合中，到21003年，这种表面变暖使SST等温线显著向极移动（平均向极移动2.1 ± 0.7 °;在某些地区可达300-400 km;图1）。相比之下，表明南极绕极流（ACC）内平均锋面位置（包括极地rFont）的输送核心显示没有这种系统性位移，即使在最强的气候强迫情景下（代表性浓度路径8.5，RCP8.5）4，只有小于100 km的区域位移和整个集合的显著不确定性（图1）。在其他研究中也出现了不适当地使用SST作为未来锋面位置的代表2，5。这些都是一个持续的症状，但不正确的，叙述，极锋，其强大的属性梯度和上升流，正在向极地转移，并将继续这样做，在未来的变暖情景。在过去十年和更长的时间里，物理海洋学界对ACC锋的移动进行了大量辩论。然而，最近达成了一个广泛的共识，即从1993年至今的卫星观测期间，锋面位置没有统计上的显著趋势，而最初的说法中的错误来源却被确定为相反7 -9。此外，虽然上一代耦合气候模式（CMIP 3）表明ACC锋可能在未来世纪发生向极移动，但最近的CMIP 5中更高的分辨率和改进的物理学表明整个集合4没有系统性的变化。我们还强调，虽然与锋面位置相关的ACC电流核心可以在CMIP 5集合中追踪，但这些模型在表示上升流和其他已知对生产力具有重要控制作用的锋面过程（包括垂直分层和涡动活动变化）方面存在重大局限性10。因此，调查未来气候对锋面生产力和企鹅觅食成功的影响，需要一个更复杂的处理比可以得到一个简单的SST度量在当前一代的耦合气候模型。我们在这里并没有提出一个更好的代表觅食成功，而是敦促谨慎使用简单的经验得出的代理复杂和不断变化的海洋特征，如前线和地区的上升流;我们强调，未来对南大洋性质和环流的预测存在很大的不确定性11，我们鼓励采取多学科方法，了解气候变化将如何影响生态系统12，以便在今后的分析中正确地纳入这些因素。海洋动力学在王企鹅活动范围估计中的作用
1British Antarctic Survey, Cambridge, UK. 2College of Marine Science, University of South Florida, St Petersburg, FL, USA. *e-mail: andmei@bas.ac.uk In a recent Article, Cristofari et al.1 discuss the impact that movements of the Antarctic Polar Front have had on historical king penguin populations, and make future projections based on potential climate change scenarios. They predict that 70% of the world’s breeding population will be severely impacted as the Polar Front, with its nutrient-rich upwelling and high productivity, moves polewards beyond the foraging range of many penguin colonies. We highlight here, however, that a detailed analysis of the models used does not support the projection of a poleward shift in the Polar Front’s future position, and that recent analyses show no evidence for such a shift having occurred in the last several decades. As a proxy for the Polar Front location, and thus foraging range, Cristofari et al.1 use the position of a constant sea surface temperature (SST) isotherm. On short timescales this proxy aligns with the actual front, identified as deep-reaching strong horizontal property gradients and high flow speeds, and correlates well with penguin foraging range2. Under future climate forcing scenarios, however, the SST and the location of the deep front (and its associated nutrient gradients, strong flow and upwelling) become decoupled due to strong surface warming, throwing into question the ongoing validity of an empirical correlation between SST and foraging range. In the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble of models used by Cristofari et al., this surface warming displaces SST isotherms significantly poleward by 21003 (mean displacement of 2.1 ± 0.7o polewards; up to 300–400 km in some regions; Fig. 1). In contrast, the transport core indicating the mean frontal locations (including the Polar rFont) within the Antarctic Circumpolar Current (ACC) displays no such systematic displacement, even under the strongest climate forcing scenario (Representative Concentration Pathway 8.5, RCP8.5)4, with only regional shifts of less than 100 km and significant uncertainty across the ensemble (Fig. 1). The inappropriate use of SST as a proxy for future frontal location also appears in other studies2,5. These are symptomatic of a persistent, yet incorrect, narrative that the Polar Front, with its strong property gradients and upwelling, is shifting poleward, and will continue to do so under future warming scenarios. The movement of the ACC fronts have been much debated in the physical oceanography community over the past decade and longer6. Recently, however, a broad consensus has been arrived at that there have been no statistically significant trends in the fronts’ positions during the satellite observation period from 1993 to the present, and the source of the error in initial claims to the contrary has been identified7–9. Additionally, while the previous generation of coupled climate models (CMIP3) suggested that a poleward shift of ACC fronts may occur in the coming century, the higher resolution and improved physics in the more recent CMIP5 show no systematic shift across the ensemble4. We stress also that, while the ACC current core associated with frontal positions can be traced in the CMIP5 ensemble, such models have significant limitations in their representation of upwelling and other frontal processes known to be important controls on productivity, including vertical stratification and changes in eddy activity10. Investigation of future climatic impacts on frontal productivity and penguin foraging success thus requires a more sophisticated treatment than can be obtained using a simple SST metric in the current generation of coupled climate models. We do not propose here a better proxy for foraging success, but instead urge caution in the use of simplistic empirically derived proxies for complex and changing oceanographic features such as fronts and regions of upwelling; we stress that there is great uncertainty in future projections of Southern Ocean properties and circulation11, and we encourage multidisciplinary approaches to understand how climate change will impact ecosystems12 so that such factors can be correctly incorporated in future analyses. The role of ocean dynamics in king penguin range estimation
影响因子：
3.6
作者：
Meijers, A. J. S.;Shuckburgh, E.;Wang, Z.
通讯作者：
Wang, Z.