scholarly journals Moisture Changes in the Northern Xinjiang Basin Over the Past 2400 years as Documented in Pollen Records of Jili Lake

2021 ◽  
Vol 9 ◽  
Author(s):  
Yulin Xiao ◽  
Lixiong Xiang ◽  
Xiaozhong Huang ◽  
Keely Mills ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Terrestrial Ecosystem ◽  
Warm Period ◽  
Ice Age ◽  
Pollen Record ◽  
Humid Climate ◽  
Northern Xinjiang ◽  
The Past ◽  
Climate Background

Regional humidity is important for terrestrial ecosystem development, while it differs from region to region in inland Asia, knowledge of past moisture changes in the lower basin of northern Xinjiang remainly largely unclear. Based on a pollen record from Jili Lake, the Artemisia/(Amaranthaceae + Ephedra) (Ar/(Am + E)) ratio, as an index of regional humidity, has recorded four relatively dry phases: 1) 400 BCE to 1 CE, 2) the Roman Warm Period (RWP; c. 1–400 CE), 3) the Medieval Warm Period (MWP; c. 850–1200 CE) and 4) the Current Warm Period (CWP; since 1850 CE). In contrast, the Dark Age Cold Period (DACP; c. 400–850 CE) and the Little Ice Age (LIA; c. 1200–1850 CE) were relatively wet. Lower lake levels in a relatively humid climate background indicated by higher aquatic pollen (Typha and Sparganium) after c. 1700 CE are likely the result of intensified irrigation for agriculture in the catchment as documented in historical records. The pollen Ar/(Am + E) ratio also recorded a millennial-scale wetting trend from 1 CE to 1550 CE which is concomitant with a long-term cooling recorded in the Northern Hemisphere.

A High-Resolution 11,400-Yr Diatom Record from Lake Victoria, East Africa

1997 ◽  
Vol 47 (1) ◽  
pp. 81-89 ◽  
Author(s):  
J.Curt Stager ◽  
Brian Cumming ◽  
Loren Meeker
Keyword(s):  
Little Ice Age ◽  
Lake Victoria ◽  
Ice Age ◽  
Pollen Record ◽  
Diatom Assemblages ◽  
Climatic Fluctuations ◽  
The Past ◽  
Phytoplankton Communities ◽  
Abrupt Changes ◽  
Globally Distributed

AbstractFine-interval (∼30–45 yr) sampling of a core from Lake Victoria's Damba Channel shows that numerous abrupt changes in the lake's diatom assemblages have occurred in response to climatic fluctuations over the past 11,40014C yr. Four distinct climatic phases bounded by sudden transitions are inferred: (1) variably dry ∼11,400–10,000 yr B.P., (2) humid ∼10,000–7200 yr B.P., (3) more seasonal ∼7200–2200 yr B.P., and (4) more arid ∼2200–0 yr B.P., with a dry “Little Ice Age” event ∼600–200 yr B.P. The diatom-inferred paleoclimatic history for northern Lake Victoria closely resembles that inferred from a well-dated pollen record from Pilkington Bay. Spectral analysis of the diatom record reveals strong periodicities including globally distributed ∼2360–2550, ∼1400, ∼1030–1130, and ∼500 cal-yr cycles. Repeated, rapid shifts betweenAulacoseira- andNitzschia-dominated diatom assemblages suggest that post-1960 changes in the lake's phytoplankton communities have had earlier, climate-driven analogs.

scholarly journals Vegetation changes in the Hotyn Upland over the last 2000 years (based on pollen data)

2019 ◽  
Vol 28 (1) ◽  
pp. 51-58 ◽  
Author(s):  
N. Gerasimenko ◽  
T. Yurchenko ◽  
Ye. Rohozin
Keyword(s):  
Little Ice Age ◽  
Environmental Changes ◽  
Medieval Warm Period ◽  
Warm Period ◽  
Ice Age ◽  
Humid Climate ◽  
Cool Period ◽  
Surface Samples ◽  
Pollen Surface ◽  
Short Period

Pollen study of two soil sections, located in two different relief positions (the gully bottom at Sadgora 1 and the upper part of a slope at Ridkivtsi I) enables us to show vegetational and climatic changes in the Bukovyna area (the Chernivtsi region) during the last 2000 years (the end of the Early Subatlantic, the Middle and Late Subatlantic). The reconstructions of past vegetation are based on the analyses of pollen surface samples, taken from the soils of different ecotops in the sites’ vicinity. The reconstructed short-period phases of environmental change correspond well with those established in other areas. These are the end of the “Roman warm period” (before the 14C date of 1.74 ka BP), with the humid climate; the relatively dry “Dark Ages cool period” (before the 14C date of 1.19 ka BP); the wet “Medieval warm period”; the cool “Little Ice Age” (with its wetter beginning and drier ending) and the modern warm phase (the last 150 years).Centennial environmental changes − the cooling within the Medieval Warming (XI cent.) and the warming within the “Little Ice Age” (XV cent.) – have been detected. Human impact on the vegetation can be demonstrated – forest clearance (with the presence of particles of microscopic charcoal and pollen of pyrophitic plants), the introduction of thermophilous walnut during warm periods, and the appearance of pasture lands in the place of former fern patches and woods during the “Little Ice Age”, and the last warm phase (with the presence of pollen of pastoral synanthropic plants). In the last 2000 years, broad-leaved woodland, dominated by hornbeam, grew extensively near Sadgora and Ridkivtsi only during the “Medieval Warm Period”.

scholarly journals Was the Little Ice Age more or less El Niño-like than the Medieval Climate Anomaly? Evidence from hydrological and temperature proxy data

2017 ◽  
Vol 13 (3) ◽  
pp. 267-301 ◽  
Author(s):  
Lilo M. K. Henke ◽  
F. Hugo Lambert ◽  
Dan J. Charman
Keyword(s):  
Little Ice Age ◽  
Large Scale ◽  
Global Climate ◽  
Ice Age ◽  
Medieval Climate Anomaly ◽  
Climate Anomaly ◽  
Proxy Data ◽  
The Past ◽  
Proxy Records

Abstract. The El Niño–Southern Oscillation (ENSO) is the most important source of global climate variability on interannual timescales and has substantial environmental and socio-economic consequences. However, it is unclear how it interacts with large-scale climate states over longer (decadal to centennial) timescales. The instrumental ENSO record is too short for analysing long-term trends and variability and climate models are unable to accurately simulate past ENSO states. Proxy data are used to extend the record, but different proxy sources have produced dissimilar reconstructions of long-term ENSO-like climate change, with some evidence for a temperature–precipitation divergence in ENSO-like climate over the past millennium, in particular during the Medieval Climate Anomaly (MCA; AD  ∼  800–1300) and the Little Ice Age (LIA; AD  ∼  1400–1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using weighting based on empirical orthogonal function (EOF) to create two new large-scale reconstructions of ENSO-like climate change derived independently from precipitation proxies and temperature proxies. The method is developed and validated using model-derived pseudo-proxy experiments that address the effects of proxy dating error, resolution, and noise to improve uncertainty estimations. We find no evidence that temperature and precipitation disagree over the ENSO-like state over the past millennium, but neither do they agree strongly. There is no statistically significant difference between the MCA and the LIA in either reconstruction. However, the temperature reconstruction suffers from a lack of high-quality proxy records located in ENSO-sensitive regions, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite, and model representations of ENSO are needed to fully resolve the discrepancies found among proxy records and establish the long-term stability of this important mode of climatic variability.

Biogeochemical evidence for environmental and vegetation changes in peatlands from the middle Yangtze river catchment during the medieval warm period and little ice Age

The Holocene ◽  
2021 ◽  
pp. 095968362110259
Author(s):  
Jia Sun ◽  
Chunmei Ma ◽  
Bin Zhou ◽  
Jiawei Jiang ◽  
Cheng Zhao
Keyword(s):  
Solar Irradiance ◽  
Little Ice Age ◽  
Asian Summer Monsoon ◽  
Eastern China ◽  
Medieval Warm Period ◽  
Warm Period ◽  
Ice Age ◽  
Jiangxi Province ◽  
Humid Climate ◽  
Climatic Fluctuations

The reconstruction of past climates and vegetation can provide valuable information for understanding the mechanisms of the variability of the East Asian summer monsoon in eastern China. In this study, organic geochemical evidence from the compositions of sedimentary leaf-wax stable isotopes and n-alkane parameters investigates the changes in vegetation and climate over the last 1200 years in the Xiyaohu peatland, Jiangxi Province, southeast China. Combined with temperature records, three climatic periods are presented: (a) a warm and humid period with an increase in C4 plants from 900 to 1450 AD, which coincides with the Medieval Warm Period (MWP); (b) a cool and dry period with the expansion of C3 plants from 1450 to 1800 AD, coinciding with the Little Ice Age (LIA); and (c) the Present Warm Period (PWP) from 1800 AD until the present, with warm and wet conditions. The sub-stages within the MWP and LIA intervals are also presented. The earlier MWP stage (900–1125 AD) was drier than the latter one (1125–1450 AD), and the earlier LIA stage (1450–1650 AD) was drier than the late LIA (1650–1800 AD). Increased solar irradiance and enhanced El Niño activities are related to the warm and humid climate during the MWP and PWP, whereas reduced solar irradiance and La Niña activities correspond to the cool and dry climate during the LIA. The present results provide insights into paleoclimatic changes in eastern monsoonal China and provide an understanding of centennial-scale climatic fluctuations and their driving factors.

scholarly journals Temperature changes of the past 2000 yr in China and comparison with Northern Hemisphere

2013 ◽  
Vol 9 (1) ◽  
pp. 507-523 ◽  
Author(s):  
Q. Ge ◽  
Z. Hao ◽  
J. Zheng ◽  
X. Shao
Keyword(s):  
Northern Hemisphere ◽  
Little Ice Age ◽  
Warming Trend ◽  
Warm Period ◽  
Ice Age ◽  
Global Changes ◽  
Least Squares Regression ◽  
Temperature Variations ◽  
Temperature Changes ◽  
The Past

Abstract. In this paper, we use principal components and partial least squares regression analysis to reconstruct a composite profile of temperature variations in China, and the associated uncertainties, at a decadal resolution over the past 2000 yr. Our aim is to contribute a new temperature time series to the paleoclimatic strand of the Asia2K working group, which is part of the PAGES (Past Global Changes) project. The reconstruction was developed using proxy temperature data, with relatively high confidence levels, from five locations across China, and an observed temperature dataset provided by Chinese Meteorological Administration covering the decades from the 1870s to the 1990s. Relative to the 1870s–1990s climatology, our two reconstructions both show three warm intervals during the 270s–390s, 1080s–1210s, and after the 1920s; temperatures in the 260s–400s, 560s–730s and 970s–1250s were comparable with those of the Present Warm Period. Temperature variations over China are typically in phase with those of the Northern Hemisphere (NH) after 1100, a period which covers the Medieval Climate Anomaly, Little Ice Age, and Present Warm Period. The recent rapid warming trend that developed between the 1840s and the 1930s occurred at a rate of 0.91° C/100 yr. The temperature difference between the cold spell (−0.74° C in the 1650s) during the Little Ice Age, and the warm peak of the Present Warm Period (0.08° C in the 1990s) is 0.82° C at a centennial time scale.

scholarly journals Climate Variability in Central Europe during the Last 2500 Years Reconstructed from Four High-Resolution Multi-Proxy Speleothem Records

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 166
Author(s):  
Sarah Waltgenbach ◽  
Dana F. C. Riechelmann ◽  
Christoph Spötl ◽  
Klaus P. Jochum ◽  
Jens Fohlmeister ◽  
...  
Keyword(s):  
Trace Elements ◽  
High Resolution ◽  
Climate Variability ◽  
Little Ice Age ◽  
Medieval Warm Period ◽  
Warm Period ◽  
Ice Age ◽  
Cold Period ◽  
Cave System ◽  
Dark Ages

The Late Holocene was characterized by several centennial-scale climate oscillations including the Roman Warm Period, the Dark Ages Cold Period, the Medieval Warm Period and the Little Ice Age. The detection and investigation of such climate anomalies requires paleoclimate archives with an accurate chronology as well as a high temporal resolution. Here, we present 230Th/U-dated high-resolution multi-proxy records (δ13C, δ18O and trace elements) for the last 2500 years of four speleothems from Bunker Cave and the Herbstlabyrinth cave system in Germany. The multi-proxy data of all four speleothems show evidence of two warm and two cold phases during the last 2500 years, which coincide with the Roman Warm Period and the Medieval Warm Period, as well as the Dark Ages Cold Period and the Little Ice Age, respectively. During these four cold and warm periods, the δ18O and δ13C records of all four speleothems and the Mg concentration of the speleothems Bu4 (Bunker Cave) and TV1 (Herbstlabyrinth cave system) show common features and are thus interpreted to be related to past climate variability. Comparison with other paleoclimate records suggests a strong influence of the North Atlantic Oscillation at the two caves sites, which is reflected by warm and humid conditions during the Roman Warm Period and the Medieval Warm Period, and cold and dry climate during the Dark Ages Cold period and the Little Ice Age. The Mg records of speleothems Bu1 (Bunker Cave) and NG01 (Herbstlabyrinth) as well as the inconsistent patterns of Sr, Ba and P suggests that the processes controlling the abundance of these trace elements are dominated by site-specific effects rather than being related to supra-regional climate variability.

Ice-Core Pollen Record of Climatic Changes in the Central Andes during the last 400 yr

2005 ◽  
Vol 64 (2) ◽  
pp. 272-278 ◽  
Author(s):  
Kam-biu Liu ◽  
Carl A. Reese ◽  
Lonnie G. Thompson
Keyword(s):  
Little Ice Age ◽  
Ice Core ◽  
Climatic Changes ◽  
Ice Age ◽  
Striking Similarity ◽  
Pollen Record ◽  
Dry Period ◽  
Proxy Records ◽  
Ice Cap ◽  
Ice Accumulation

AbstractThis paper presents a high-resolution ice-core pollen record from the Sajama Ice Cap, Bolivia, that spans the last 400 yr. The pollen record corroborates the oxygen isotopic and ice accumulation records from the Quelccaya Ice Cap and supports the scenario that the Little Ice Age (LIA) consisted of two distinct phases�"a wet period from AD 1500 to 1700, and a dry period from AD 1700 to 1880. During the dry period xerophytic shrubs expanded to replace puna grasses on the Altiplano, as suggested by a dramatic drop in the Poaceae/Asteraceae (P/A) pollen ratio. The environment around Sajama was probably similar to the desert-like shrublands of the Southern Bolivian Highlands and western Andean slopes today. The striking similarity between the Sajama and Quelccaya proxy records suggests that climatic changes during the Little Ice Age occurred synchronously across the Altiplano.

Glacier fluctuations during the past millennium in Garibaldi Provincial Park, southern Coast Mountains, British Columbia

2007 ◽  
Vol 44 (9) ◽  
pp. 1215-1233 ◽  
Author(s):  
Johannes Koch ◽  
John J Clague ◽  
Gerald D Osborn
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Ice Age ◽  
Southern Coast ◽  
Coast Mountains ◽  
The Past ◽  
Glacier Fluctuations ◽  
Garibaldi Provincial Park ◽  
Provincial Park ◽  
Past Millennium

The Little Ice Age glacier history in Garibaldi Provincial Park (southern Coast Mountains, British Columbia) was reconstructed using geomorphic mapping, radiocarbon ages on fossil wood in glacier forefields, dendrochronology, and lichenometry. The Little Ice Age began in the 11th century. Glaciers reached their first maximum of the past millennium in the 12th century. They were only slightly more extensive than today in the 13th century, but advanced at least twice in the 14th and 15th centuries to near their maximum Little Ice Age positions. Glaciers probably fluctuated around these advanced positions from the 15th century to the beginning of the 18th century. They achieved their greatest extent between A.D. 1690 and 1720. Moraines were deposited at positions beyond present-day ice limits throughout the 19th and early 20th centuries. Glacier fluctuations appear to be synchronous throughout Garibaldi Park. This chronology agrees well with similar records from other mountain ranges and with reconstructed Northern Hemisphere temperature series, indicating global forcing of glacier fluctuations in the past millennium. It also corresponds with sunspot minima, indicating that solar irradiance plays an important role in late Holocene climate change.

scholarly journals The Response Time of Glaciers in Iceland to Changes in climate

1986 ◽  
Vol 8 ◽  
pp. 100-101 ◽  
Author(s):  
Tómas Jóhannesson
Keyword(s):  
Response Time ◽  
Time Variation ◽  
Little Ice Age ◽  
Wave Theory ◽  
Warm Period ◽  
Ice Age ◽  
Kinematic Wave

Records of the time variation of the terminus position of Icelandic glaciers since 1700 show clear responses to the little ice age and to the warm period from 1930 to 1960. These data are used to deduce limits for the response time of the glaciers. The response time turns out to be of the order of one or two hundred years. This is much shorter than the “long response time” of Nye’s kinematic wave theory.

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