scholarly journals Corrigendum to "Quantitative reconstruction of precipitation changes on the NE Tibetan Plateau since the Last Glacial Maximum – extending the concept of pollen source area to pollen-based climate reconstructions from large lakes" published in Clim. Past, 10, 21–39, 2014

2014 ◽  
Vol 10 (1) ◽  
pp. 207-207
Author(s):  
Y. Wang ◽  
U. Herzschuh ◽  
L. S. Shumilovskikh ◽  
S. Mischke ◽  
H. J. B. Birks ◽  
...  

2020 ◽  
Vol 8 ◽  
Author(s):  
Xiangjun Liu ◽  
Lu Cong ◽  
Xiangzhong Li ◽  
David Madsen ◽  
Yixuan Wang ◽  
...  

Environmental conditions on the Tibetan Plateau (TP) during the last glacial maximum (LGM) are poorly known. Existing studies of environmental proxies and climate model simulations are contradictory, with interpretations varying between cold-dry and cold-wet environmental conditions which differentially influenced lake volumes, loess deposition and vegetation communities across the TP. Genetic and archaeological studies suggest anatomically modern paleolithic foragers initially occupied the TP between 60 and 30 ka, and may have seasonally occupied the TP during the LGM. Hence, a better understanding for LGM environmental conditions is needed in order to estimate whether paleolithic foragers could have survived on the TP during the extreme LGM cold stage. Here we report the investigation of lacustrine sediments and beach deposits within two paleoshorelines around Dagze Co on the southern TP, ∼22 and ∼42 m higher than the present lake level. Optical age estimates suggest the sediments were deposited during the LGM and mid-Holocene, respectively. TraCE-21 climate model simulation results suggest that net annual LGM precipitation in the Dagze Co basin was lower than the mid-Holocene, but about the same as that of the past 1,000 years. Combining the optical age estimates with TraCE-21 and CAM4 climate model simulation results, we deduce that increased summer precipitation and glacier meltwater supply, combined with decreased lake surface evaporation, produced LGM lake levels ∼22 m higher than present. We also synthesized paleoenvironmental records reported across the TP spanning the LGM. This synthesis suggests that the LGM climate in the northern TP was cold and dry, but that some of the southern TP was cold and wet. These relatively wetter LGM conditions in the southern TP may have favored the growth of cold-resistant plants which, in turn, may have supported larger herbivore populations, and provided food for paleolithic foragers. We conclude that seasonal or short-term human occupation of the TP during the LGM was thus more likely in the southern TP than in the north.


2017 ◽  
Author(s):  
Heiko Paeth ◽  
Christian Steger ◽  
Jingmin Li ◽  
Sebastian G. Mutz ◽  
Todd A. Ehlers

Abstract. Assessing paleo-climatic changes across the Tibetan Plateau and the underlying driving mechanisms provides insights for the natural variability in the Earth's climate system in response to tectonic processes and global climate change. In this study, we use a high-resolution regional climate model to investigate various episodes of distinct climate states over the Tibetan Plateau region during the Cenozoic rise of the Plateau and Quaternary glacial/interglacial cycles. The main objective is to compare climate changes during the Miocene-Pliocene uplift period with climate anomalies during the last glacial maximum and the mid-Holocene optimum, based on a consistent modeling framework. Reduced plateau elevation leads to regionally differentiated patterns of higher temperature and lower precipitation amount on the plateau itself, whereas surrounding regions are subject to colder conditions. In particular, Central Asia receives much more precipitation prior to the uplift, mainly due to a shift of the stationary wave train over Eurasia. Cluster analysis indicates that the continental-desert type climate, which is widespread over Central Asia today, appears with the Tibetan Plateau reaching 50 % of its present-day elevation. The mid-Holocene is characterized by slightly colder temperatures, and the last glacial maximum by considerably colder conditions over most of central and southern Asia. Precipitation anomalies during these episodes are less pronounced and spatially heterogeneous over the Tibetan Plateau. The simulated changes are in good agreement with available paleo-climatic reconstructions from proxy data. The present-day climate classification is only slightly sensitive to the changed boundary conditions in the Quaternary Quaternary. It is shown that in some regions of the Tibetan Plateau the climate anomalies during the Quaternary Quaternary have been as strong as the changes occurring during the uplift period.


2021 ◽  
Author(s):  
◽  
Sarah Louise Callard

<p>The project builds upon existing knowledge of late Quaternary palaeoenvironmenta change and tests the recently developed New Zealand INTIMATE (Integration of Ice Marine and Terrestrial archive) climate event stratigraphy (NZ-I CES; 30-8 ka). Four pollen and sediment records from three climatically contrasting regions in the South Island provide a vegetation and climate history for this area between 38-4 ka. In this study, the Last Glacial Cold Period (LGCP; c. 31.4-18.9 ka) is characterised by a two step cooling, with the coldest conditions, reaching possibly >5.3°C cooling, occurring between 21-19 ka, marking the Last Glacial Maximum. A new precipitation proxy using macrophyte pollen concentrations at an eastern South Island site suggests dominantly dry conditions prevailed during the LGCP except for two periods of wetter climate around 26-24 ka and 21 ka. The dry periods correspond with evidence of glacial advance, colder environments and possibly increased intensity of the southern westerlies. Conversely, the wet periods coincide with reduced glacial activity, milder climates and decreased westerly wind intensity. Deglaciation began between 18.9-18.4 ka followed by rapid climate amelioration culminating with Dacrydium cuppressinum-dominant lowland forest at western sites as early as 11.9 ka, indicative of the start of the Holocene. A disturbance in forest development occurs between 13.4-11.9 ka in one record and may be indicative of a minor cooling within the timeframe of a late glacial climate reversal recognised in the NZI-CES. Overall the project results (timing and pattern of climate change) broadly align with the NZ-I CES. However, there are some disparities, in particular during the LGCP, which this study suggests began at least 3-4 ka earlier than concluded in the NZ-I CES. The NZ-I CES oversimplifies the complexity of the LGCP which contains evidence of significant climate variability that may be important for an understanding of the possible forcing factors on climate change. The chronology derived from the current study supports recent evidence that points towards a younger, refined age of 25.4 ka for the Kawakawa/Oruanui Tephra, a key chronostratigraphic marker for the LGCP. Pollen-climate models and Environmental Lapse Rates were used to quantify changes in mean annual temperatures with sometimes conflicting results. This research reveals some limitations of the current New Zealand pollen-climate transfer function when applied to reconstruction of cold climate periods in particular. These include a lack of limitations with modern analogues and a number of wide-ranging pollen taxa that encompass a broad climate envelope. The current research also highlights the potential of regional climate regimes and spatial differences in vegetation and inferred climate reconstructions. These differences pose a major limitation for a New Zealand-wide composite. While the NZ-I CES provides a valuable framework of climate change during a period of large climate variability, results of this study highlight aspects that need further consideration and revision.</p>


2021 ◽  
Author(s):  
◽  
Sarah Louise Callard

<p>The project builds upon existing knowledge of late Quaternary palaeoenvironmenta change and tests the recently developed New Zealand INTIMATE (Integration of Ice Marine and Terrestrial archive) climate event stratigraphy (NZ-I CES; 30-8 ka). Four pollen and sediment records from three climatically contrasting regions in the South Island provide a vegetation and climate history for this area between 38-4 ka. In this study, the Last Glacial Cold Period (LGCP; c. 31.4-18.9 ka) is characterised by a two step cooling, with the coldest conditions, reaching possibly >5.3°C cooling, occurring between 21-19 ka, marking the Last Glacial Maximum. A new precipitation proxy using macrophyte pollen concentrations at an eastern South Island site suggests dominantly dry conditions prevailed during the LGCP except for two periods of wetter climate around 26-24 ka and 21 ka. The dry periods correspond with evidence of glacial advance, colder environments and possibly increased intensity of the southern westerlies. Conversely, the wet periods coincide with reduced glacial activity, milder climates and decreased westerly wind intensity. Deglaciation began between 18.9-18.4 ka followed by rapid climate amelioration culminating with Dacrydium cuppressinum-dominant lowland forest at western sites as early as 11.9 ka, indicative of the start of the Holocene. A disturbance in forest development occurs between 13.4-11.9 ka in one record and may be indicative of a minor cooling within the timeframe of a late glacial climate reversal recognised in the NZI-CES. Overall the project results (timing and pattern of climate change) broadly align with the NZ-I CES. However, there are some disparities, in particular during the LGCP, which this study suggests began at least 3-4 ka earlier than concluded in the NZ-I CES. The NZ-I CES oversimplifies the complexity of the LGCP which contains evidence of significant climate variability that may be important for an understanding of the possible forcing factors on climate change. The chronology derived from the current study supports recent evidence that points towards a younger, refined age of 25.4 ka for the Kawakawa/Oruanui Tephra, a key chronostratigraphic marker for the LGCP. Pollen-climate models and Environmental Lapse Rates were used to quantify changes in mean annual temperatures with sometimes conflicting results. This research reveals some limitations of the current New Zealand pollen-climate transfer function when applied to reconstruction of cold climate periods in particular. These include a lack of limitations with modern analogues and a number of wide-ranging pollen taxa that encompass a broad climate envelope. The current research also highlights the potential of regional climate regimes and spatial differences in vegetation and inferred climate reconstructions. These differences pose a major limitation for a New Zealand-wide composite. While the NZ-I CES provides a valuable framework of climate change during a period of large climate variability, results of this study highlight aspects that need further consideration and revision.</p>


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