Holocene temperature and moisture evolution in Central Asia

Abstract

Holocene moisture evolution in the arid Central Asia region, dominated by the westerly circulation system, has been shown to be in drastic contrast with that in Asian monsoonal regions. Although several patterns have been identified, the exact form of moisture evolution and associated controlling mechanisms remain elusive. Meanwhile, Holocene terrestrial temperature records from the region are very limited, hindering our understanding how Holocene temperature has evolved into the current state and its association with moisture evolution. Here we present Holocene temperature and moisture records from several lake sediment cores, based on the alkenone proxies. The geographical locations of studied lakes, from ~37°N to ~55°N, extend to the southern and northern limits of the current arid Central Asia region and allow us to infer spatiotemporal patterns of Holocene climate change in Central Asia. Two types of patterns could be identified. To the south, Holocene warm season temperature evolution is characterized by a general cooling trend, accompanied with enhanced moisture and a typical warm/dry association. To the north, it is substantially warmer and wetter during the late Holocene, while extreme coolness and dryness occurred during the mid-Holocene (~5-7 ka), with a typical warm/wet association. For both types, it appears that temperature and moisture evolution was closely related, indicating a temperature control on moisture evolution although with two contrasting mechanisms. Therefore, our temperature records help explain previously identified maximum wetness over the last one millennium or around 4-7 ka in Central Asia. However, the strong temperature contrast between the south and north of Central Asia during the early and mid-Holocene and its relaxation during the late Holocene remain to be further investigated.