scholarly journals New chronology of the Chinese loess-paleosol sequence by leaf wax δD records during the past 800 k.y.

Geology ◽  
2021 ◽  
Author(s):  
Zheng Wang ◽  
Weiguo Liu ◽  
Hong Wang ◽  
Yunning Cao ◽  
Jing Hu ◽  
...  
Keyword(s):  
Global Climate ◽  
Last Interglacial ◽  
Chinese Loess ◽  
The Past ◽  
Leaf Wax ◽  
Climate Event ◽  
Δ18o And Δd ◽  
Climate Events ◽  
Plant Wax ◽  
Hydrogen Isotopic Composition

The Chinese loess-paleosol sequences provide important archives for studying paleoenvironmental changes. However, the lack of independent and accurate time scales hinders the study between loess and other records. Asian stalagmite δ18O records indicate synchronous patterns of paleoprecipitation δ18O over large geographic regions. The record of hydrogen isotopic composition of plant wax (δDwax) in Chinese loess is also controlled by rainwater δD. Both share a common origin. The linear relationship between rainfall δ18O and δD variance provides the basis to tie together chronologies of the same climate event in different records. Here, we show a new loess chronology by correlating chronologies of marker boundaries of the prominent climate chronozones in stalagmite δ18O and summer insolation to the equivalent climate stratigraphy in the loess δDwax sequence. We first developed and tested this novel methodology with data since the last interglacial on a millennial scale, and then applied this approach to the loess δDwax sequence for the past 800 k.y. to improve the traditional chronology based on magnetic susceptibility and grain size. The new δDwax time series provides not only an improved chronology for studying paleoclimate changes during interglacial intervals, it also represents a unique database with which to better understand the links between the Asian monsoon changes in the Chinese loess and other global climate events, especially for the periods prior to 640 ka, for which stalagmite records are not available.

scholarly journals Supplemental Material: New chronology of the Chinese loess-paleosol sequence by leaf wax δD records during the past 800 k.y.

2021 ◽  
Author(s):  
Zheng Wang ◽  
Weiguo Liu ◽  
et al.
Keyword(s):  
Spectrum Analysis ◽  
Chinese Loess ◽  
The Past ◽  
Leaf Wax

Materials, methods, and interpretations, Figure S1 (site description and loess records from layer S1), Figure S2 (comparing δD<sub>wax</sub> of layer S2 in central and south CLP), Figure S3 (spectrum analysis of loess δD<sub>wax</sub>), and Figure S4 (the differences between two age-models in paleosol and loess layers).<br>

scholarly journals Supplemental Material: New chronology of the Chinese loess-paleosol sequence by leaf wax δD records during the past 800 k.y.

2021 ◽  
Author(s):  
Zheng Wang ◽  
Weiguo Liu ◽  
et al.
Keyword(s):  
Spectrum Analysis ◽  
Chinese Loess ◽  
The Past ◽  
Leaf Wax

Materials, methods, and interpretations, Figure S1 (site description and loess records from layer S1), Figure S2 (comparing δD<sub>wax</sub> of layer S2 in central and south CLP), Figure S3 (spectrum analysis of loess δD<sub>wax</sub>), and Figure S4 (the differences between two age-models in paleosol and loess layers).<br>

scholarly journals Entropy-based dynamic graph embedding for anomaly detection on multiple climate time series

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gen Li ◽  
Jason J. Jung
Keyword(s):  
Time Series ◽  
Graph Embedding ◽  
Time Interval ◽  
Dynamic Graph ◽  
The Past ◽  
Entropy Measurement ◽  
Climate Event ◽  
Synthetic Datasets ◽  
Climate Time Series ◽  
Climate Events

AbstractAbnormal climate event is that some meteorological conditions are extreme in a certain time interval. The existing methods for detecting abnormal climate events utilize supervised learning models to learn the abnormal patterns, but they cannot detect the untrained patterns. To overcome this problem, we construct a dynamic graph by discovering the correlation among the climate time series and propose a novel dynamic graph embedding model based on graph entropy called EDynGE to discriminate anomalies. The graph entropy measurement quantifies the information of the graphs and constructs the embedding space. We conducted experiments on synthetic datasets and real-world meteorological datasets. The results showed that EdynGE model achieved a better F1-score than the baselines by 43.2%, and the number of days of abnormal climate events has increased by 304.5 days in the past 30 years.

scholarly journals Asian inland wildfires driven by glacial–interglacial climate change

2020 ◽  
Vol 117 (10) ◽  
pp. 5184-5189 ◽  
Author(s):  
Yongming Han ◽  
Zhisheng An ◽  
Jennifer R. Marlon ◽  
Raymond S. Bradley ◽  
Changlin Zhan ◽  
...  
Keyword(s):  
High Intensity ◽  
Large Scale ◽  
Global Climate ◽  
Chinese Loess Plateau ◽  
Potential Importance ◽  
Quaternary Period ◽  
Chinese Loess ◽  
Ice Volume ◽  
The Past ◽  
The Chinese Loess Plateau

Wildfire can influence climate directly and indirectly, but little is known about the relationships between wildfire and climate during the Quaternary, especially how wildfire patterns varied over glacial–interglacial cycles. Here, we present a high-resolution soot record from the Chinese Loess Plateau; this is a record of large-scale, high-intensity fires over the past 2.6 My. We observed a unique and distinct glacial–interglacial cyclicity of soot over the entire Quaternary Period synchronous with marine δ18O and dust records, which suggests that ice-volume-modulated aridity controlled wildfire occurrences, soot production, and dust fluxes in central Asia. The high-intensity fires were also found to be anticorrelated with global atmospheric CO2 records over the past eight glacial–interglacial cycles, implying a possible connection between the fires, dust, and climate mediated through the iron cycle. The significance of this hypothetical connection remains to be determined, but the relationships revealed in this study hint at the potential importance of wildfire for the global climate system.

scholarly journals Iron in the NEEM ice core relative to Asian loess records over the last glacial–interglacial cycle

2020 ◽  
Author(s):  
Cunde Xiao ◽  
Zhiheng Du ◽  
Mike J Handley ◽  
Paul A Mayewski ◽  
Junji Cao ◽  
...  
Keyword(s):  
Industrial Revolution ◽  
Mineral Dust ◽  
Ice Core ◽  
Interglacial Period ◽  
Anthropogenic Contamination ◽  
Last Interglacial ◽  
Chinese Loess ◽  
Last Glacial ◽  
The Past ◽  
The Last Glacial

Abstract Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO2) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial–interglacial cycle in response to Earth's orbital cycles. In the last glacial–interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core.

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

Modulation of the relationship between summer temperatures in the Qinghai–Tibetan Plateau and Arctic over the past millennium by external forcings

2021 ◽  
pp. 1-9
Author(s):  
Feng Shi ◽  
Anmin Duan ◽  
Qiuzhen Yin ◽  
John T Bruun ◽  
Cunde Xiao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Global Climate ◽  
Volcanic Eruptions ◽  
Warm Period ◽  
Temperature Correlation ◽  
The Past ◽  
External Forcings ◽  
Centennial Variation ◽  
Summer Temperatures ◽  
Past Millennium

Abstract The Qinghai–Tibetan Plateau and Arctic both have an important influence on global climate, but the correlation between climate variations in these two regions remains unclear. Here we reconstructed and compared the summer temperature anomalies over the past 1,120 yr (900–2019 CE) in the Qinghai–Tibetan Plateau and Arctic. The temperature correlation during the past millennium in these two regions has a distinct centennial variation caused by volcanic eruptions. Furthermore, the abrupt weak-to-strong transition in the temperature correlation during the sixteenth century could be analogous to this type of transition during the Modern Warm Period. The former was forced by volcanic eruptions, while the latter was controlled by changes in greenhouse gases. This implies that anthropogenic, as opposed to natural, forcing has acted to amplify the teleconnection between the Qinghai–Tibetan Plateau and Arctic during the Modern Warm Period.

scholarly journals Ensemble models on palaeoclimate to predict India's groundwater challenge

2013 ◽  
Vol 2 (3) ◽  
Author(s):  
Partha Sarathi Datta
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Humid Climate ◽  
Ensemble Models ◽  
North West ◽  
The Past ◽  
The North ◽  
14C Age

In many parts of the world, freshwater crisis is largely due to increasing water consumption and pollution by rapidly growing population and aspirations for economic development, but, ascribed usually to the climate. However, limited understanding and knowledge gaps in the factors controlling climate and uncertainties in the climate models are unable to assess the probable impacts on water availability in tropical regions. In this context, review of ensemble models on δ18O and δD in rainfall and groundwater, 3H- and 14C- ages of groundwater and 14C- age of lakes sediments helped to reconstruct palaeoclimate and long-term recharge in the North-west India; and predict future groundwater challenge. The annual mean temperature trend indicates both warming/cooling in different parts of India in the past and during 1901–2010. Neither the GCMs (Global Climate Models) nor the observational record indicates any significant change/increase in temperature and rainfall over the last century, and climate change during the last 1200 yrs BP. In much of the North-West region, deep groundwater renewal occurred from past humid climate, and shallow groundwater renewal from limited modern recharge over the past decades. To make water management to be more responsive to climate change, the gaps in the science of climate change need to be bridged.

Hydroclimatic variability in loess δDwax records from the central Chinese Loess Plateau over the past 250 ka

2018 ◽  
Vol 155 ◽  
pp. 49-57 ◽  
Author(s):  
Zheng Wang ◽  
Zhisheng An ◽  
Zhonghui Liu ◽  
Xiaoke Qiang ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Chinese Loess Plateau ◽  
Chinese Loess ◽  
The Past ◽  
Hydroclimatic Variability

Drought variation trends in different subregions of the Chinese Loess Plateau over the past four decades

2012 ◽  
Vol 115 ◽  
pp. 167-177 ◽  
Author(s):  
Baoqing Zhang ◽  
Pute Wu ◽  
Xining Zhao ◽  
Yubao Wang ◽  
Jiawen Wang ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Chinese Loess Plateau ◽  
Chinese Loess ◽  
The Past ◽  
Variation Trends ◽  
The Chinese Loess Plateau
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