Abstract
Abstract. The mid-Holocene period (MH) has long been an ideal target for the validation of general circulation model (GCM) results against reconstructions gathered in global datasets. These studies aim to test GCM sensitivity, mainly to seasonal changes induced by the orbital parameters (longitude of the perihelion). Despite widespread agreement between model results and data on the MH climate, some important differences still exist. There is no consensus on the continental size (the area of the temperature anomaly) of the MH thermal climate response, which makes regional quantitative reconstruction critical to obtain a comprehensive understanding of the MH climate patterns. Here, we compare the annual and seasonal outputs from the most recent Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3) models with an updated synthesis of climate reconstruction over China, including, for the first time, a seasonal cycle of temperature and precipitation. Our results indicate that the main discrepancies between model and data for the MH climate are the annual and winter mean temperature. A warmer-than-present climate condition is derived from pollen data for both annual mean temperature (∼0.7 K on average) and winter mean temperature (∼1 K on average), while most of the models provide both colder-than-present annual and winter mean temperature and a relatively warmer summer, showing a linear response driven by the seasonal forcing. By conducting simulations in BIOME4 and CESM, we show that surface processes are the key factors creating the uncertainties between models and data. These results pinpoint the crucial importance of including the non-linear responses of the surface water and energy balance to vegetation changes.
Highlights
Much attention from paleoclimate studies has been focused on the current interglacial, especially the midHolocene (MH; 6 ± 0.5 ka)
A warmer-than-present annual climate condition (∼ 0.7 K on average) is derived from pollen data, with the largest increase occurring in the northeast (3–5 K) and a decrease in the northwest and on Tibetan Plateau
In response to the seasonal insolation change prescribed in PMIP3 for the MH, all models produce similar large-scale patterns for seasonal temperature and precipitation
Summary
Much attention from paleoclimate studies has been focused on the current interglacial (the Holocene), especially the midHolocene (MH; 6 ± 0.5 ka). The MH provides an excellent case study on which to base an evaluation of the climate response to changes in the distribution of insolation. Much work has been done to reconstruct the paleoclimate change based on different proxies at the global and continental scale Y. Lin et al.: Mid-Holocene climate change over China: model–data discrepancy al., 1993; Kohfeld and Harrison, 2000; Prentice et al, 2000; Bartlein et al, 2011). The greatest progress in understanding MH climate change and variability has consistently been made by comparing large-scale analyses of data with simulations from global climate models (Joussaume et al, 1999; Liu et al, 2004; Harrison et al, 2014)
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