Holocene moisture evolution in arid central Asia and its out-of-phase relationship with Asian monsoon history

https://doi.org/10.1016/j.quascirev.2007.10.017Get rights and content

Abstract

We synthesize palaeoclimate records from the mid-latitude arid Asian region dominated today by the Westerlies (“arid central Asia” (ACA)) to evaluate spatial and temporal patterns of moisture changes during the Holocene. Sediment records from 11 lakes with reliable chronologies and robust proxies were selected to reconstruct moisture histories based on a five-class ordinal wetness index with assigned scores from the driest to wettest periods at individual sites for 200-year time slices. The proxies used in these records include pollen and diatom assemblages, sediment lithology, lake levels, and geochemistry (mainly isotope) data. The results of our synthesis show that ACA as a whole experienced synchronous and coherent moisture changes during the Holocene, namely a dry early Holocene, a wetter (less dry) early to mid-Holocene, and a moderately wet late Holocene. During the early Holocene most of the lakes experienced very low water levels and even dried out before ca 8 ka (1 ka=1000 cal a BP). Hence the effective-moisture history in ACA is out-of-phase with that in monsoonal Asia as documented by numerous palaeoclimate records. In monsoonal Asia, a strong summer monsoon and humid climate characterized the early Holocene, and a weakened summer monsoon and drier climate prevailed during the late Holocene, which were mainly controlled by changes in low-latitude summer insolation. In contrast, we propose that the pattern of Holocene effective-moisture evolution in the westerly dominated ACA was mainly determined by North Atlantic sea-surface temperatures (SSTs) and high-latitude air temperatures that affect the availability, amount and transport of water vapor. Also, topography of the Tibetan Plateau and adjacent Asian highlands could have contributed to the intensification of dry climate in ACA during the early Holocene, as a result of strengthening the subsidence of dry air masses, associated with stronger uplift motion on the plateau by intense heating under a stronger summer insolation. Summer insolation might have played a key role in directly controlling moisture conditions in ACA but only after the northern hemisphere ice-sheets had disappeared in the mid- and late Holocene.

Introduction

A variety of proxy records has been used to document climate change during the Holocene in many parts of the world. Understanding the spatial and temporal patterns of climate change in a given region may provide insights into the underlying climate-forcing mechanisms. In east and south Asia, Asian monsoon variations during the Holocene have been well-documented by precisely dated cave deposits (e.g., Fleitmann et al., 2003; Yuan et al., 2004; Shao et al., 2006). The Indian and East Asian summer monsoons were enhanced shortly after the Younger Dryas (YD) at the onset of the Holocene, was strongest in the early and mid-Holocene, and weakened after the mid-Holocene. This pattern closely follows changes in summer insolation at low latitudes (Kutzbach, 1981). Similar changes in the strength of the Asian monsoons have been documented by other proxy records from peats (Hong et al., 2003), lake sediments (Lister et al., 1991; Gu et al., 1993; Hodell et al., 1999; Xiao et al., 2004; Shen et al., 2005) and marine sediments (Wang et al., 1999; Gupta et al., 2003). However, Holocene climate patterns in arid central Asia (referred to as ACA in this paper) are poorly documented and understood. This lack of understanding is partly due to the complex interplay of competing forcing factors controlling regional climate; these factors include the low-latitude summer monsoonal circulation, the mid-latitude Westerlies, and orographic influences of the Tibetan Plateau. For example, the western part of ACA experienced a wet mid-Holocene and a dry early and late-Holocene, as documented by lake-level changes in the Aral Sea (Boomer et al., 2000), while the eastern part of the region near the monsoon limit showed a variable wetness during the entire Holocene, with some possibly drier intervals in the mid-Holocene (Chen et al., 2003a, Chen et al., 2003b, Chen et al., 2006; Schettler et al., 2006; Zhao et al., 2007).

For expediting the following discussion, we divide the southeastern part of the Eurasian continent into three climatically distinct regions: humid Asia mainly controlled by summer monsoonal circulation; ACA dominated by the Westerlies; and a transitional zone around modern Asian summer monsoon limit in semi-arid northwest China and the southern Mongolian Plateau. In this study we focus only on the westerly dominated ACA for several reasons. First, it is one of the driest regions in the world, and its sparse water resources and fragile ecosystems in a general dry climate would be very sensitive to abrupt changes in rainfall (Qin et al., 2005; Narisma et al., 2007). Second, many lakes in this region, including Aral Sea and Caspian Sea, experienced similar changes during the Holocene (Qin and Yu, 1998). Also, a dramatic decline in lake levels has occurred during the last century at several lakes; such changes have attracted considerable attention because of concerns about shortage of water resources and related ecological problems (Qin and Yu, 1998; Ferronskii et al., 2003). However, a recent lake-level rise and lake expansion in the last 20 years at most lakes in arid west China suggests a possible shift from a warm-dry to a warm-humid climate under global warming (Shi et al., 2007). Several syntheses have been published over the last decade, which provide valuable insights into understanding the Holocene moisture history of the region. However, most of these reviews have focused only on parts of arid central Asia, as previous studies were mostly restricted to China (Shi et al., 1993, Shi et al., 1994; An et al., 2000; Feng et al., 2006). A comprehensive review of Holocene moisture evolution for the entire region is useful to decipher and understand the complex palaeo-moisture evolution under the same atmosphere circulation, namely the Westerlies. In addition, there are potential problems with chronology and proxy interpretations in some of the early published palaeo records (cf. Qin and Yu, 1998; An et al., 2000; Feng et al., 2006). As a result, there remains confusion about the regional climate patterns, and there is an urgent need to standardize and synthesize palaeoclimatic information about ACA mainly based on recent published records. Such an updated synthesis will help not only understand the Holocene moisture history of the region, but also provide information to assess climate simulations using general circulation model (GCM) and regional climate model (RCM, e.g., Sato and Kimura, 2005).

Here we review 11 lake records from the westerlies-dominated region of ACA (Fig. 1). The objectives of this study are (1) to review recently published proxy climate records from lake sediments; (2) to derive a semi-quantitative reconstruction of moisture history during the Holocene; and (3) to understand potential controls and mechanisms of the observed temporal and spatial patterns.

Section snippets

Data sources and analyses

In ACA there are abundant climatic records from continental eolian deposits, including loess and dune deposits. However, these records tend to have low temporal resolution and be discontinuous, even in the thick loess deposits on the Chinese loess Plateau that have high accumulation rates (e.g., Lu et al., 2006; Stevens et al., 2006). Therefore, in this study we have selected records from lake sediments based on four criteria: (1) the selected sites should be from extant lakes, so that any

Temporal moisture change during the Holocene in arid central Asia

Many lakes, including Bosten Lake (5), Bayan Nuur (6), Juyan Lake (9), Gun Nuur (10) and Hulun Nuur (11), were totally dried up or were very shallow during the early Holocene before 8 ka (Fig. 3). Large deep lakes, such as the Aral Sea, Issyk-Kul and Lake Van, were still present, but at low lake levels. The Caspian Sea also reportedly had a lower water level before 8 ka than at present (Kazanci et al., 2004), though this site is not included in this synthesis because of its low sampling

Spatial patterns of Holocene moisture evolution in arid central Asia and monsoonal Asia

We divide the Holocene into four periods to investigate the regional patterns of Holocene moisture change in ACA and compared them with those in monsoonal Asia: early Holocene (ca 11–8 ka), mid-Holocene (8–5 ka), late Holocene (5–2 ka), and the last 2 ka. The Holocene moisture histories show distinct spatial patterns between ACA and monsoonal Asia (Fig. 4). Climate was clearly dry in the westerly dominated ACA during the early Holocene but it was humid during the mid-Holocene (Fig. 4). A moderately

Contrasting patterns of Holocene moisture histories between arid central Asia and monsoonal Asia

Various proxy data from speleothem, lake sediments, peat cores and marine sediments as discussed above show similar patterns in effective moisture and precipitation change during the Holocene in monsoonal Asia. In their review, An et al. (2000) proposed that the Holocene optimum of the East Asian monsoon was asynchronous among different regions. However, evidence from recently well-dated records does not appear to support this hypothesis (Feng et al., 2006). Also, our synthesis shows that the

Possible forcing mechanisms for Holocene moisture evolution in arid central Asia

The Holocene ACA moisture history appears to be similar to the pattern of the Holocene sea-surface temperatures (SSTs) in the North Atlantic (e.g., Kaplan and Wolfe, 2006) and in the Norwegian Sea (Koç et al., 1993; Birks and Koç, 2002; Figs. 6c and d), as well as the air temperatures recorded in the GRIP ice-core (Dahl-Jensen et al., 1998; Fig. 6e) and in the European pollen records (Davis et al., 2003). The North Atlantic was warmest in the mid-Holocene between ca 9–8 ka and 5 ka after the

Conclusions

On the basis of palaeoclimatic records from 11 selected lakes in westerly dominated ACA, we find an out-of-phase relationship in Holocene moisture histories between ACA and the Asian monsoon-controlled region. In contrast to monsoonal Asia where maximum moisture occurred during the early to mid-Holocene, maximum moisture (precipitation) occurred during the mid-Holocene in ACA. We suggest that the out-of-phase pattern results from different controlling factors of moisture change in both regions.

Acknowledgements

This synthesis results from discussions at the INQUA RACHAD 2006 Workshop held on 25–27 July 2006 in Lanzhou, China. We thank Zhaodong Feng (Lanzhou University, China), Hilary Birks (University of Bergen, Norway), Georg Schettler (Geoforschungszentrum Potsdam, Germany), Xunlin Yang (Lanzhou University, China) and other workshop participants for their valuable contributions and discussion. We also thank two anonymous reviewers for their constructive comments and suggestions. This research was

References (96)

  • U. Herzschuh

    Palaeo-moisture evolution in monsoonal Central Asia during the last 50,000 years

    Quaternary Science Reviews

    (2006)
  • U. Herzschuh et al.

    Holocene vegetation and climate of the Alashan Plateau, NW China, reconstructed from pollen data

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2004)
  • D.A. Hodell et al.

    Paleoclimate of Southwestern China for the past 50,000 yr inferred from lake sediment records

    Quaternary Research

    (1999)
  • Y.T. Hong et al.

    Correlation between Indian Ocean summer monsoon and North Atlantic climate during the Holocene

    Earth and Planetary Science Letters

    (2003)
  • Y.T. Hong et al.

    Inverse phase oscillations between the East Asian and Indian Ocean summer monsoons during the last 12 000 years and paleo-El Niño

    Earth and Planetary Science Letters

    (2005)
  • M.R. Kaplan et al.

    Spatial and temporal variability of Holocene temperature in the North Atlantic region

    Quaternary Research

    (2006)
  • E.B. Karabanov et al.

    Ecological collapse of Lake Baikal and Lake Hovsgol ecosystems during the Last Glacial and consequences for aquatic species diversity

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2004)
  • N. Kazanci et al.

    Sedimentary and environmental characteristics of the Gilan-Mazenderan plain, northern Iran: influence of long- and short-term Caspian water level fluctuations on geomorphology

    Journal of Marine Systems

    (2004)
  • N. Koç et al.

    Paleoceanographic reconstructions of surface ocean conditions in the Greenland, Iceland and Norwegian Seas through the last 14 ka based on diatoms

    Quaternary Science Reviews

    (1993)
  • G. Landmann et al.

    Dating Lateglacial abrupt climate changes in the 14,570 yr long continuous varve record of Lake Van, Turkey

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (1996)
  • Y.X. Li et al.

    Sensitive moisture response to Holocene millennial-scale climate variations in the mid-Atlantic region, USA

    The Holocene

    (2007)
  • G. Lister et al.

    Lake Qinghai, China: closed-basin lake levels and the oxygen isotope record for ostracoda since the latest Pleistocene

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (1991)
  • F. Nara et al.

    Response of phytoplankton productivity to climate change recorded by sedimentary photosynthetic pigments in Lake Hovsgol (Mongolia) for the last 23,000 years

    Quaternary International

    (2005)
  • I. Overeem et al.

    Small-scale stratigraphy in a large ramp delta: recent and Holocene sedimentation in the Volga delta, Caspian Sea

    Sedimentary Geology

    (2003)
  • J.A. Peck et al.

    Mid to Late Holocene climate change in north central Mongolia as recorded in the sediments of Lake Telmen

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2002)
  • W.R. Peltier et al.

    Global glacial ice volume and Last Glacial Maximum duration from an extended Barbados sea level record

    Quaternary Science Reviews

    (2006)
  • A.A. Prokopenko et al.

    Basin-wide sedimentation changes and deglacial lake-level rise in the Hovsgol basin, NW Mongolia

    Quaternary International

    (2005)
  • B. Qin et al.

    Implications of lake level variations at 6 and 18 ka in mainland Asia

    Global and Planetary Change

    (1998)
  • R.D. Ricketts et al.

    The Holocene paleolimnology of Lake Issyk-Kul, Kyrgyzstan: trace element and stable isotope composition of ostracodes

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2001)
  • P.E. Tarasov et al.

    Climate in northern Eurasia 6000 years ago reconstructed from pollen data

    Earth and Planetary Science Letters

    (1999)
  • L.G. Thompson et al.

    Ice core evidence for asynchronous glaciation on the Tibetan Plateau

    Quaternary International

    (2006)
  • E. Van Campo et al.

    Holocene environmental changes in Bangong Co basin (Western Tibet). Part 2: The pollen record

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (1996)
  • J. Vandenberghe et al.

    Penetration of Atlantic westerly winds into central and East Asia

    Quaternary Science Reviews

    (2006)
  • L. Wang et al.

    East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

    Marine Geology

    (1999)
  • P.X. Wang et al.

    Evolution and variability of the Asian monsoon system: state of the art and outstanding issues

    Quaternary Science Reviews

    (2005)
  • B. Wünnemann et al.

    A Holocene sedimentary record from Bosten Lake, China

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2006)
  • J.L. Xiao et al.

    Holocene vegetation variation in the Daihai Lake region of north-central China: a direct indication of the Asian monsoon climatic history

    Quaternary Science Reviews

    (2004)
  • Y. Zhao et al.

    Holocene vegetation and climate history at Hurleg Lake in the Qaidam Basin, northwest China

    Review of Palaeobotany and Palynology

    (2007)
  • C.J.A. Birks et al.

    A high-resolution diatom record of late-Quaternary sea-surface temperatures and oceanographic conditions from the eastern Norwegian Sea

    Boreas

    (2002)
  • J. Böhner

    General climatic controls and topoclimatic variations in central and high Asia

    Boreas

    (2006)
  • A.J. Broccoli et al.

    The effects of orography on midlatitude northern hemisphere dry climates

    Journal of Climate

    (1992)
  • C. Bronk Ramsey

    Radiocarbon calibration and analysis of stratigraphy: the OxCal Program

    Radiocarbon

    (1995)
  • C. Bronk Ramsey

    Development of the radiocarbon program OxCal

    Radiocarbon

    (2001)
  • Climate changes of the last 18,000 years: observations and model simulations

    Science

    (1988)
  • F.H. Chen et al.

    A mid-Holocene drought interval as evidenced by lake desiccation in the Alashan Plateau, Inner Mongolia, China

    Chinese Science Bulletin

    (2003)
  • F.H. Chen et al.

    Holocene environmental change inferred from a high-resolution pollen records of Lake Zhuyeze, Arid China

    The Holocene

    (2006)
  • D. Dahl-Jensen et al.

    Past temperatures directly from the Greenland ice sheet

    Science

    (1998)
  • The temperature of Europe during the Holocene reconstructed from pollen data

    Quaternary Science Reviews

    (2003)
  • Cited by (1009)

    View all citing articles on Scopus
    View full text