Paleolake salinity evolution in the Qaidam Basin (NE Tibetan Plateau) between ~42 and 29 Ma: Links to global cooling and Paratethys sea incursions

Author(s):  
Chengcheng Ye ◽  
Yibo Yang ◽  
Xiaomin Fang ◽  
Weilin Zhang ◽  
Chunhui Song ◽  
...  

<p>Global cooling, the early uplift of the Tibetan Plateau, and the retreat of the Paratethys are three main factors that regulate long-term climate change in the Asian interior during the Cenozoic. However, the debated elevation history of the Tibetan Plateau and the overlapping climate effects of the Tibetan Plateau uplift and Paratethys retreat makes it difficult to assess the driving mechanism on regional climate change in a particular period. Some recent progress suggests that precisely dated Paratethys transgression/regression cycles appear to have fluctuated over broad regions with low relief in the northern Tibetan Plateau in the middle Eocene–early Oligocene, when the global climate was characterized by generally continuous cooling followed by the rapid Eocene–Oligocene climate transition (EOT). Therefore, a middle Eocene–early Oligocene record from the Asian interior with unambiguous paleoclimatic implications offers an opportunity to distinguish between the climatic effects of the Paratethys retreat and those of global cooling.</p><p>Here, we present a complete paleolake salinity record from middle Eocene to early Miocene (~42-29 Ma) in the Qaidam Basin using detailed clay boron content and clay mineralogical investigations. Two independent paleosalimeters, equivalent boron and Couch’s salinity, collectively present a three-staged salinity evolution, from an oligohaline–mesohaline environment in the middle Eocene (42-~34 Ma) to a mesosaline environment in late Eocene-early Oligocene (~34-~29 Ma). This clay boron-derived salinity evolution is further supported by the published chloride-based and ostracod-based paleosalinity estimates in the Qaidam Basin. Our quantitative paleolake reconstruction between ~42 and 29 Ma in the Qaidam Basin resembles the hydroclimate change in the neighboring Xining Basin, of which both present good agreement with changes of marine benthic oxygen isotope compositions. We thus speculated that the secular trend of clay boron-derived paleolake salinity in ~42-29 Ma is primarily controlled by global cooling, which regulates regional climate change by influencing the evaporation capacity in the moisture source of Qaidam Basin. Superimposed on this trend, the Paratethys transgression/regression cycles served as an important factor regulating wet/dry fluctuations in the Asian interior between ~42 and ~34 Ma.</p>

2018 ◽  
Vol 22 (5) ◽  
pp. 3087-3103 ◽  
Author(s):  
Huanghe Gu ◽  
Zhongbo Yu ◽  
Chuanguo Yang ◽  
Qin Ju ◽  
Tao Yang ◽  
...  

Abstract. An ensemble simulation of five regional climate models (RCMs) from the coordinated regional downscaling experiment in East Asia is evaluated and used to project future regional climate change in China. The influences of model uncertainty and internal variability on projections are also identified. The RCMs simulate the historical (1980–2005) climate and future (2006–2049) climate projections under the Representative Concentration Pathway (RCP) RCP4.5 scenario. The simulations for five subregions in China, including northeastern China, northern China, southern China, northwestern China, and the Tibetan Plateau, are highlighted in this study. Results show that (1) RCMs can capture the climatology, annual cycle, and interannual variability of temperature and precipitation and that a multi-model ensemble (MME) outperforms that of an individual RCM. The added values for RCMs are confirmed by comparing the performance of RCMs and global climate models (GCMs) in reproducing annual and seasonal mean precipitation and temperature during the historical period. (2) For future (2030–2049) climate, the MME indicates consistent warming trends at around 1 ∘C in the entire domain and projects pronounced warming in northern and western China. The annual precipitation is likely to increase in most of the simulation region, except for the Tibetan Plateau. (3) Generally, the future projected change in annual and seasonal mean temperature by RCMs is nearly consistent with the results from the driving GCM. However, changes in annual and seasonal mean precipitation exhibit significant inter-RCM differences and possess a larger magnitude and variability than the driving GCM. Even opposite signals for projected changes in average precipitation between the MME and the driving GCM are shown over southern China, northeastern China, and the Tibetan Plateau. (4) The uncertainty in projected mean temperature mainly arises from the internal variability over northern and southern China and the model uncertainty over the other three subregions. For the projected mean precipitation, the dominant uncertainty source is the internal variability over most regions, except for the Tibetan Plateau, where the model uncertainty reaches up to 60 %. Moreover, the model uncertainty increases with prediction lead time across all subregions.


2019 ◽  
Vol 40 (4) ◽  
pp. 2403-2417 ◽  
Author(s):  
Mingshan Deng ◽  
Xianhong Meng ◽  
Zhaoguo Li ◽  
Yaqiong Lyv ◽  
Huajin Lei ◽  
...  

2013 ◽  
Vol 9 (2) ◽  
pp. 1485-1508 ◽  
Author(s):  
Y. F. Miao ◽  
X. M. Fang ◽  
F. L. Wu ◽  
M. T. Cai ◽  
C. H. Song ◽  
...  

Abstract. Cenozoic climate changes in inner Asia provide a basis for understanding linkages between global cooling, the Tibetan Plateau uplift, and possibly the development of the East Asian monsoon. Based on the compiled palynological results from the western Qaidam Basin, this study reconstructed an 18 Ma record of changing vegetation and paleoclimates since the middle Miocene. Thermophilic taxa percentages were highest between 18 and 14 Ma and decreased after 14 Ma, corresponding closely with the Middle Miocene Climatic Optimum (MMCO) between 18 and 14 Ma and the following global climatic cooling. After 3.6 Ma, the thermophilic taxa percentages further decreased, showing the inevitable relations with the ice-sheets enlargement in the North Hemisphere. During the same period of time, the increase in xerophytic taxa percentages and decrease in conifers percentages imply aridification in both the basin and surrounding mountains since 18 Ma. These results indicate that global cooling mainly controlled the climate change from a relative warm-wet stage to a cold-dry stage during the late Cenozoic at the western Qaidam Basin, and that the Tibetan Plateau uplift also contributed in contrast to the East Asian summer monsoon.


2015 ◽  
Vol 7 (3) ◽  
pp. 2445-2479 ◽  
Author(s):  
H. Jiang ◽  
T. Deng ◽  
Y. Li ◽  
H. Xu

Abstract. Exchange records of terrestrial mammals can be combined with available tectonic and climatic documents to evaluate major biological and environmental events. Previous studies identified four carnivoran dispersals between Eurasia and North America in the Neogene, namely, at ∼ 20, 13–11, 8–7, and ∼ 4 Ma. In order to evaluate driving mechanism of these biological events, we collected, compared and analyzed a large number of published records. The results indicate that the carnivoran dispersal from Eurasia to North America at ∼ 20 Ma was probably caused by intense tectonic movements in Asia. During 13–11 Ma, global cooling possibly drove the mammal exchanges between Eurasia and North America. By comparison, the carnivoran dispersal from Eurasia to North America at 8–7 Ma was probably caused by the combination of global cooling and tectonic movements of the Tibetan Plateau. Similar to during 13–11 Ma, the carnivoran exchanges between Eurasia and North America at ∼ 4 Ma were possibly driven by global cooling.


2020 ◽  
Author(s):  
Xiaoyan Yang ◽  
Juzhi Hou ◽  
Feixue San

Abstract Continental chemical weathering has been suggested to affect the concentration of atmospheric carbon dioxide that influences global climate change at different time scales. Various indices for chemical weathering have been adopted to investigate past change in chemical weathering intensity and climate change on oceanic and lacustrine sediment archives. The reliability of the chemical weathering indices has been questioned as most sediments likely originate from multiple types of bedrock that may experience various degrees of chemical weathering and can thus be reliably robust indicators of climate and paleoclimate. Here we present Sr-type (e.g. Rb/Sr Sr/Ba) and Na-type (e.g. CIA CIW PIA CPA) chemical weathering indices for top soils across the southern Tibetan Plateau to discuss the chemical weathering characteristic in the Tibetan Plateau and to examine their response to regional climate variation. The results of chemical indices and the A-CN-K ternary plot show that the southern Tibetan Plateau is under the carbonate control of the primary chemical weathering stage with the cold-dry climate. Correlation analyses show shat Sr-type indices co-vary with mean annual temperature and annual precipitation while Na-type indices show little consistence with regional climate. The climate condition is the dominant control of Sr-type indices of top soils in the study area and the bedrock may be the dominant control for the Na-type indices. We also compared the corresponding indices at a Holocene lacustrine sediment profile in the Qaidam Basin in the northeast Tibetan Plateau with regional climatic records which strongly supports our observation in the top soils. The results of the study suggest that for the relative cold and dry climate in Tibetan Plateau the Sr-type indices are more sensitive to climate condition than Na-type indices. This suggests that the Sr-type indices are likely more suitable than Na-type indices to reflect the change of climate on the Tibetan Plateau. Caution should be taken for using the Na-type indices for reconstructing the past change in climate for the study area.


Author(s):  
Yanling Song ◽  
Chunyi Wang ◽  
Hans W. Linderholm ◽  
Jinfeng Tian ◽  
Ying Shi ◽  
...  

The Tibetan plateau is one of the most sensitive areas in China and has been significantly affected by global warming. From 1961 to 2017, the annual air temperature increased by 0.32 °C/decade over the Tibetan Plateau, which is the highest in the whole of China. Furthermore, this is a trend that is projected to continue by 0.30 °C/decade from 2018 to 2050 due to global warming using the Regional Climate Model version 4 (RegCM4). The increased temperature trend in recent decades has been highest in winter, which has been positive for the safe dormancy of winter wheat. In order to investigate agricultural adaptation to climate change in the Tibetan plateau, we used the World Food Studies (WOFOST) cropping systems model and weather data from the regional climate model RegCM4, to simulate winter wheat production in Guide county between 2018 and 2050. The simulated winter wheat potential yields amounted to 6698.3 kg/ha from 2018 to 2050, which showed the wheat yields would increase by 81%, if winter wheat was planted instead of spring wheat in the Tibetan Plateau with the correct amount of irrigation water. These results indicate that there are not only risks to crop yields from climate change, but also potential benefits. Global warming introduced the possibility to plant winter wheat instead of spring wheat over the Tibetan Plateau. These findings are very important for farmers and government agencies dealing with agricultural adaptation in a warmer climate.


2021 ◽  
Vol 14 (5) ◽  
pp. 2827-2841
Author(s):  
Ziyu Huang ◽  
Lei Zhong ◽  
Yaoming Ma ◽  
Yunfei Fu

Abstract. Precipitation is the key component determining the water budget and climate change of the Tibetan Plateau (TP) under a warming climate. This high-latitude region is regarded as “the Third Pole” of the Earth and the “Asian Water Tower” and influences the eco-economy of downstream regions. However, the intensity and diurnal cycle of precipitation are inadequately depicted by current reanalysis products and regional climate models (RCMs). Spectral nudging is an effective dynamical downscaling method used to improve precipitation simulations of RCMs by preventing simulated fields from drifting away from large-scale reference fields, but the most effective manner of applying spectral nudging over the TP is unclear. In this paper, the effects of spectral nudging parameters (e.g., nudging variables, strengths, and levels) on summer precipitation simulations and associated meteorological variables were evaluated over the TP. The results show that using a conventional continuous integration method with a single initialization is likely to result in the over-forecasting of precipitation events and the over-forecasting of horizontal wind speeds over the TP. In particular, model simulations show clear improvements in their representations of downscaled precipitation intensity and its diurnal variations, atmospheric temperature, and water vapor when spectral nudging is applied towards the horizontal wind and geopotential height rather than towards the potential temperature and water vapor mixing ratio. This altering of the spectral nudging method not only reduces the wet bias of water vapor in the lower troposphere of the ERA-Interim reanalysis (when it is used as the driving field) but also alleviates the cold bias of atmospheric temperatures in the upper troposphere, while maintaining the accuracy of horizontal wind features for the regional model field. The conclusions of this study imply how driving field errors affect model simulations, and these results may improve the reliability of RCM results used to study the long-term regional climate change.


2020 ◽  
Vol 133 (1-2) ◽  
pp. 149-158 ◽  
Author(s):  
Weitao Wang ◽  
Peizhen Zhang ◽  
Zhicai Wang ◽  
Kang Liu ◽  
Hongyan Xu ◽  
...  

Abstract To help understand the relationship between global cooling and Tibetan uplift in the middle to late Miocene, multiple proxy data including carbonate stable isotope records, magnetic susceptibility, and sediment color references were obtained from a magnetostratigraphic section (14.5–6.0 Ma) of the Wushan Basin along the northeastern margin of the Tibetan Plateau. New proxies identify two phase changes that may have been controlled by global cooling and tectonic deformation at this time. During 14.5–13.2 Ma, positive shifts of ∼2.0‰ in δ18O and δ13C, an increase in lightness (L*), and a decrease in redness (a*) suggest gradually increasing aridity. Relatively high δ18O and δ13C values and low a*/L* and magnetic susceptibility values continue until ca. 10 Ma, when δ18O and δ13C significantly decrease and redness as well as magnetic susceptibility significantly increase. The negative shifts in δ18O and δ13C and increases in redness and magnetic susceptibility at 10 Ma are consistent with coeval basin environment and provenance changes. Combining these data with basin analysis, we suggest that global cooling was the dominant factor and Tibetan uplift was the subordinate factor for the middle Miocene aridification of the Wushan Basin. In contrast, the contribution of Tibetan uplift was dominant and global climate change was subordinate in the late Miocene basin paleogeographic reorganization.


2020 ◽  
Author(s):  
Ziyu Huang ◽  
Lei Zhong ◽  
Yaoming Ma ◽  
Yunfei Fu

Abstract. Precipitation is the key component determining the water budget and climate change of the Tibetan Plateau (TP) under a warming climate. This high-latitude region is regarded as the Third Pole of the Earth and the Asian Water Tower and influences the eco-economy of downstream regions. However, the intensity and diurnal cycle of precipitation are inadequately depicted by current reanalysis products and regional climate models (RCMs). Spectral nudging is an effective dynamical downscaling method used to improve precipitation simulations of RCMs by preventing simulated fields from drifting away from large-scale reference fields, but the most effective manner of applying spectral nudging over the TP is unclear. In this paper, the effects of spectral nudging parameters (e.g., nudging variables, strengths and levels) on summer precipitation simulations and associated meteorological variables were evaluated over the TP. The results show that using a conventional continuous integration method with a single initialization is likely to result in the overforecasting of precipitation events and the overforecasting of horizontal wind speeds over the TP. In particular, model simulations show clear improvements in their representations of downscaled precipitation intensity and its diurnal variations, atmospheric temperature and water vapor when spectral nudging is applied towards the horizontal wind and geopotential height rather than towards the potential temperature and water vapor mixing ratio. This altering to the spectral nudging method not only reduces the wet bias of water vapor in the lower troposphere of the ERA-Interim reanalysis (when it is used as the reference fields) but also alleviates the cold bias of atmospheric temperatures in the upper troposphere, while maintaining the accuracy of horizontal wind features for the simulated fields. The conclusions of this study imply how reference fields errors impact model simulations, and these results may improve the reliability of RCM results used to study the long-term regional climate change.


2013 ◽  
Vol 70 (4) ◽  
pp. 1278-1290 ◽  
Author(s):  
Zhenming Ji ◽  
Shichang Kang

Abstract A high-resolution regional climate model is used to simulate climate change over the Tibetan Plateau (TP). The model is driven at the grid spacing of 10 km by nesting the outputs of 50-km-resolution simulations. The results show that the models can capture the spatial and temporal distributions of the surface air temperature over the TP. The so-called double-nested method has a higher horizontal resolution and represents more spatial details. For example, the temperature simulations from the double-nested method reflect the observations better compared to the 50-km-resolution models. This is mainly due to the fact that topographical effects of complex terrains are detected better at higher resolution. Although both models can represent the basic patterns of precipitation, the simulated results are not as good as those of temperature. In the future, significant warming seems to develop over the TP under two representative concentration pathway (RCP) scenarios. Greater increases occur in December–February (DJF) compared with June–August (JJA). The increasing temperature trend is more pronounced over the Gangdese Mountains and over the Himalayas than in the central TP. The projection of precipitation shows the main increases in DJF. In JJA, it predicts decreases or slight changes in the southern TP. The comparison between RCP8.5 and RCP4.5 scenarios shows a similar spatial distributions of temperature and precipitation, whereas the respective values of RCP8.5 are enhanced compared with those under RCP4.5.


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