Holocene negative coupling of summer temperature and moisture availability over southeastern arid Central Asia
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Holocene negative coupling of summer temperature and moisture availability over southeastern arid Central Asia Jianyong Li1,2 · Ninglian Wang1,2,3 · John Dodson4 · Hong Yan4,5,6 · Xiaojian Zhang7 · Peter Weiming Jia8 · Heikki Seppä9 Received: 15 July 2019 / Accepted: 29 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The Holocene moisture–temperature correlation on varying spatial–temporal scales in arid Central Asia (ACA) is still controversial. It has been widely reported that ACA experienced multi-centennial alternations between warm/dry and cold/wet climates over the past two millennia. However, less attention has focused on orbital-scale moisture–temperature relationship at a regional scale across ACA. Here, we contribute a framework including a set of quantitative algorithms to acquire reliable pollen-based climatic reconstructions. We apply this methodology to a new pollen record from a wetland in northern Xinjiang (southeastern ACA) for quantitative reconstructions of moisture availability (actual/potential evapotranspiration ratio, AET/PET) and summer temperature (mean temperature of the warmest month, MTWA) over circa the last 10,300 years. We select AET/PET and MTWA because they are evaluated to be most statistically independent and ecologically significant. The effect of differing spatial extents of calibration-sets on model performance is tested to determine the optimal extent. We critically assess the reliability of all reconstructions through calculations of statistical significance, analogue quality and goodness-of-fit statistics. Our final reconstructions are statistically significant with independent features of AET/PET and MTWA, showing an increasing (declining) trend of Holocene moisture (temperature). This anti-phase pattern is consistent with other records and model simulations across southeastern ACA. The data-model consistency postulates that (i) the glacier meltwater from Tien Shan (‘Water Tower of Central Asia’) is crucial to support major streamflow and watersheds over ACA, and (ii) the Holocene wetting trend may be determined by the interacting effects between decreased summer temperature and increased winter precipitation. Keywords Southeastern ACA · Pollen · AET/PET · MTWA · Holocene
1 Introduction Arid Central Asia (ACA) is currently one of the broadest semi-arid/arid geographical territories on the earth, encompassing Central Asian countries into northwestern China as well as southern Russia into western Mongolia. It topographically stretches from the Caspian Sea and Aral Sea basins in the west to the Pamirs, Tien Shan and Altai Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05319-x) contains supplementary material, which is available to authorized users. * Jianyong Li [email protected] * Ninglian Wang [email protected]
mountain systems in the middle to east. ACA is a massive reservoir for global mineral dust, hence directly or indirectly exerting a profound and widespread impact on glo
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