Department of Solar Energy and Environmental Physics, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel;
Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel.
Proc Natl Acad Sci U S A. 2018 Dec 26;115(52):E12128-E12134. doi: 10.1073/pnas.1811068115.
Global climate warming poses a significant challenge to humanity; it is associated with, e.g., rising sea level and declining Arctic sea ice. Increasing extreme events are also considered to be a result of climate warming, and they may have widespread and diverse effects on health, agriculture, economics, and political conflicts. Still, the detection and quantification of climate change, both in observations and climate models, constitute a main focus of the scientific community. Here, we develop an approach based on network and percolation frameworks to study the impacts of climate changes in the past decades using historical models and reanalysis records, and we analyze the expected upcoming impacts using various future global warming scenarios. We find an abrupt transition during the evolution of the climate network, indicating a consistent poleward expansion of the largest cluster that corresponds to the tropical area, as well as the weakening of the strength of links in the tropic. This is found both in the reanalysis data and in the Coupled Model Intercomparison Project Phase 5 (CMIP5) 21st century climate change simulations. The analysis is based on high-resolution surface (2 m) air temperature field records. We discuss the underlying mechanism for the observed expansion of the tropical cluster and associate it with changes in atmospheric circulation represented by the weakening and expansion of the Hadley cell. Our framework can also be useful for forecasting the extent of the tropical cluster to detect its influence on different areas in response to global warming.
全球气候变暖给人类带来了重大挑战；它与海平面上升和北极海冰减少等现象有关。人们还认为，极端事件的增加也是气候变暖的结果，它们可能对健康、农业、经济和政治冲突产生广泛而多样的影响。尽管如此，观测和气候模型中气候变化的检测和量化仍然是科学界的主要关注点。在这里，我们开发了一种基于网络和渗流框架的方法，使用历史模型和再分析记录来研究过去几十年气候变化的影响，并使用各种未来全球变暖情景来分析即将到来的影响。我们发现气候网络的演化过程中存在一个突然的转变，表明最大集群（对应热带地区）的极点扩张是一致的，热带地区的链路强度也在减弱。这在再分析数据和耦合模式比较计划第五阶段（CMIP5）的 21 世纪气候变化模拟中都有发现。分析基于高分辨率的地面（2 米）空气温度场记录。我们讨论了观测到的热带集群扩张的潜在机制，并将其与大气环流的变化联系起来，这些变化表现为哈德利环流的减弱和扩张。我们的框架还可用于预测热带集群的范围，以检测其对全球变暖背景下不同地区的影响。
