Mid-Holocene net precipitation changes over China: model–data comparison

Abstract

Many efforts have been made to reconstruct the moisture conditions over China during the mid-Holocene, approximately 6000 calendar years ago. However, most of them have been performed at the single site level or local scale, and the nationwide distribution of the mid-Holocene precipitation and net precipitation (precipitation minus evaporation) changes from both proxy data and simulations remains unclear. Here we first selected 36 out of 51 climate models participating in the Paleoclimate Modeling Intercomparison Project (PMIP) for their demonstrable ability to simulate the baseline climate and for the availability of evaporation data. Our analysis of the ensemble mean results of the 36 models shows that the mid-Holocene annual precipitation, evaporation, and net precipitation were 3.0%, 0.9%, and 6.9% more than the baseline period, respectively, and seasonally all three variables decreased in boreal winter and spring but increased in boreal summer and autumn on the national scale. For that period, both the pattern and magnitude of the above changes differed between the models and the sub-regions, and the interactive ocean effect had little impact overall on the country. Compared with the wetter-than-present climates derived from the records at 64 out of 69 sites across China, the models agreed qualitatively with the multi-proxy data in most parts of China, except Xinjiang and the areas between the middle and lower reaches of the Yangtze and Yellow River valleys, where drier-than-baseline climates were obtained from the 36 models.