Spatial contrasts of the Holocene hydroclimate trend between North and East Asia

• Published in: Quaternary science reviews Vol. 227; p. 106036
• Main Authors: Zhang, Yurui, Renssen, Hans, Seppä, Heikki, Valdes, Paul J., Li, Jianyong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2020; Elsevier
• Subjects: Life Sciences; Microbiology and Parasitology
• ISSN: 0277-3791; 1873-457X
• DOI: 10.1016/j.quascirev.2019.106036

The hydroclimate over Asia has undergone important changes over the Holocene with spatially asynchronous trends. Proxy-based evidence shows that North Asia was markedly drier than today during the early Holocene, whereas East Asia, influenced by the monsoon system, was substantially wetter. Yet, the causes behind this contrast are only partly understood due to a lack of overview of the most important factors. Here we explore a combination of climate proxies and multiple climate-model simulations to show that the strong contrast between the dry North Asia and wet (mid-latitude) East Asia is explained by a complex interplay between the effects of remnant ice sheets and orbital forcing. In North Asia, the climate was dry due a weakening of the westerlies and reduced atmospheric humidity, linked to the ice sheets in North America and Fennoscandia. In East Asia, contrarily, the orbitally-forced enhancement of the summer monsoons caused the early Holocene climate to be much wetter than during the present-day. These results indicate that the sensitivity of the hydroclimate in Asia to climate-forcings is spatially different, with important implications for the interpretation of past and future climate changes in this region. •Multiple climate model simulations suggest a lower early-Holocene wetness in North Asia and the followed increasing trend.•Contrasting with enhanced moisture level at onset of the Holocene and decreasing trend in East Asia.•This spatially contrast pattern is further supported by multiple lines of proxy-based moisture reconstructions.•.This N-S contrast of wetness can be attributed to different processes in response to the ice sheets and orbital forcing.•The reduced wetness over North is caused by weaken westerlies and less water vapor, linked to the melting ice sheets.•.Whereas the enhanced wetness over East Asia is due to strong monsoon circulation, mainly responding to the orbital-forcing.