| 摘要: |
| 目前，人类活动导致的温室气体增加是全球气候变化的主要驱动因素之一，但其在轨道尺度上对未来气候影响的研究却很少。利用海-陆-气耦合模式，对早全新世（距今10 ka前）、现代和未来10 ka后的气候进行了一系列敏感性数值试验，主要探讨了在轨道尺度上自然强迫和人为温室气体对全球季风区气候变化的可能影响。模拟结果表明：在自然强迫驱动下，未来10 ka后的地球气候与早全新世类似，北半球的地表温度和降水将高于工业革命前的水平，而南半球则相反。在人类活动驱动下，未来10 ka后全球地表温度将显著增加，除北美季风区外，所有季风区雨季的降水都将增加。受人类活动的影响，与工业革命前相比，极端降水和大气有效降水也将增加。在自然强迫下，雨季大气有效降水的增加主要是由于动力作用引起的大气环流增强，而人类活动引起的现代和未来10 ka后大气有效降水的增加主要是由于热力作用引起的大气水汽增加所致。 |
| 关键词: 降水 人类活动 全球季风区 数值模拟 |
| DOI：10.7515/JEE222024 |
| CSTR： |
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| 基金项目:国家自然科学基金项目（41991254）；中国科学院战略性先导科技专项（XDB40030100） |
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| Regulation of human activities on orbital-scale precipitation in global monsoon regions 【Cover】 |
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LI Xinzhou, LIU Xiaodong, MA Hongyan
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State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
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| Abstract: |
| Background, aim, and scope At present, the increase of greenhouse gases caused by human activities is one of the main drivers of global climate change, but its impact on future climate on the orbital scale has rarely been investigated. Meanwhile, climate anomalies in global monsoon regions are related to the production activities and livelihood of more than 70% of the world’s population, and have profound social and economic impacts. This study attempts to investigate the possible impacts of natural forcing and anthropogenic greenhouse gases on climate change over global monsoon regions on the orbital scale. Materials and methods A series of numerical sensitivity experiments of climate in the Early Holocene (EH), modern day, and 10000 years in the future (TTF) were performed using an atmosphere-land-ocean coupled model. By comparing and analyzing different numerical experiments and evaluating the results using Student’s t test, the relative contributions of natural and human forcing at orbital scale to the evolution of the typical global monsoon climate were discussed. Results This study focuses on the analysis of the characteristics and formation mechanism of precipitation, surface temperature, and extreme precipitation in the global monsoon regions under different forcing factors, and explores the dual effects of natural and human activities on climate. The simulation results show that, driven by natural forcing, the Earth’s climate in the TTF will be similar to that in the EH. In the northern hemisphere (NH), surface temperature and precipitation will be higher than their pre-industrial levels, whereas the southern hemisphere (SH) will experience opposite trends. Driven by human activities, the global surface temperature will significantly increase in the TTF, and precipitation in wet season will increase in all monsoon regions, except the North American monsoon region. Affected by human activities, extreme precipitation and atmospheric effective precipitation (precipitation minus evaporation, P−E) will also increase, with reference to pre-industrial levels. Discussion Through the comparison of experimental results, changes in precipitation caused by solar radiation forcing and greenhouse gas forcing can be deduced to be mainly concentrated in the monsoon region, while the change is relatively weak in the dry season. Therefore, the distribution of seasonal precipitation in the monsoon region is extremely uneven, and its annual precipitation is completely controlled by the wet season. But natural forcing and human activities have a small impact on surface evapotranspiration. Comprehensively considering precipitation and evaporation, P−E in NH is correspondingly more sensitive to solar radiation under natural forcing, and all monsoon regions are sensitive to human activities. Therefore, human activities are of vital importance in future climate prediction. Further analysis shows that, under natural forcing, the increase of P−E in wet season is mainly attributable to the enhancement of atmospheric circulation caused by the dynamic factor, while increases of P−E caused by human activities in the present day and TTF are mainly attributable to the increase of atmospheric vapor caused by the thermodynamic effect. Conclusions Under natural forcing, rainy season rainfall in TTF increases in the monsoon regions of the northern hemisphere but decreases in the southern hemisphere, compared with the pre-industrial. The increase of greenhouse gas concentration caused by modern human activities can increase precipitation in all monsoon regions. In the future, human activities will increase the contribution of extreme precipitation to total precipitation. Changes in atmospheric effective precipitation relative to the pre-industrial (Δ(P−E)) can better reflect the contributions of natural forcing and human activities on the orbital scale. Recommendations and perspectives These experiments are completely idealized based on current research and may be in conflict with the facts in the future. Therefore, it is worth further investigating future climate change using PMIP ensemble simulations and considering multiple factors comprehensively. |
| Key words: precipitation human activities global monsoon regions numerical simulation |
