Twenty first century changes in Antarctic and Southern Ocean surface climate in CMIP6
Twenty first century changes in Antarctic and Southern Ocean surface climate in CMIP6
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DOI：
10.1002/asl.984
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发表时间：
2020-05-28
影响因子：
3
通讯作者：
Wainer, Ilana
中科院分区：
文献类型：
--
作者：
Bracegirdle, Thomas J.;Krinner, Gerhard;Wainer, Ilana
进入 21 世纪二十年，越来越多的证据表明南极和南大洋气候变化对全球产生影响。因此，对南极气候系统在未来外部气候强迫的一系列情景下如何表现的可靠估计是当务之急。作为耦合模型比对项目第 6 阶段 (CMIP6) 的一部分，新模型模拟的输出为综合分析最新一代最先进的气候模型提供了机会，该模型遵循比之前的 CMIP 阶段更广泛的实验类型和情景。此处显示了 CMIP6 模型提供的主要大尺度 21 世纪南极预测，涵盖四种强迫情景：SSP1-2.6、SSP2-4.5、SSP3-7.0 和 SSP5-8.5。在这些情景中，本世纪末南极地表气温变化（相对于 1995-2014 年）为 1.3、2.5、3.7 和 4.8 摄氏度。相应的降水率变化比例为 8、16、24 和 31%。除了这些世纪末的变化之外，还对 21 世纪绝对和全球相对预测路径的情景依赖性进行了评估。区域反应的潜在差异与南极洲沿海地区特别相关，例如，那里的生态系统和冰架对跨越大气和海洋条件关键阈值的时间高度敏感。总体而言，我们发现南极洲沿海地区的预计变化并不与全球强迫呈线性关系。我们确定了两个似乎有所贡献的因素：（a）随着南大洋继续变暖，全球相对南大洋变暖趋于稳定（SSP2-4.5）和积极减缓（SSP1-2.6）情景；（b）预计南半球平流层臭氧的恢复及其对中纬度西风带的影响。主要含义是，在低强迫情景下，与未来高强迫情景相比，到 2100 年，南极洲沿海地区的地表变暖相对于全球平均地表变暖更为强烈。
Two decades into the 21st century there is growing evidence for global impacts of Antarctic and Southern Ocean climate change. Reliable estimates of how the Antarctic climate system would behave under a range of scenarios of future external climate forcing are thus a high priority. Output from new model simulations coordinated as part of the Coupled Model Intercomparison Project Phase 6 (CMIP6) provides an opportunity for a comprehensive analysis of the latest generation of state-of-the-art climate models following a wider range of experiment types and scenarios than previous CMIP phases. Here the main broad-scale 21st century Antarctic projections provided by the CMIP6 models are shown across four forcing scenarios: SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5. End-of-century Antarctic surface-air temperature change across these scenarios (relative to 1995-2014) is 1.3, 2.5, 3.7 and 4.8 degrees C. The corresponding proportional precipitation rate changes are 8, 16, 24 and 31%. In addition to these end-of-century changes, an assessment of scenario dependence of pathways of absolute and global-relative 21st century projections is conducted. Potential differences in regional response are of particular relevance to coastal Antarctica, where, for example, ecosystems and ice shelves are highly sensitive to the timing of crossing of key thresholds in both atmospheric and oceanic conditions. Overall, it is found that the projected changes over coastal Antarctica do not scale linearly with global forcing. We identify two factors that appear to contribute: (a) a stronger global-relative Southern Ocean warming in stabilisation (SSP2-4.5) and aggressive mitigation (SSP1-2.6) scenarios as the Southern Ocean continues to warm and (b) projected recovery of Southern Hemisphere stratospheric ozone and its effect on the mid-latitude westerlies. The major implication is that over coastal Antarctica, the surface warming by 2100 is stronger relative to the global mean surface warming for the low forcing compared to high forcing future scenarios.