A review of 6000–5000 cal BP climatic anomalies in China

Studies of the abrupt climate events that punctuated the warm Holocene epoch allow us to understand the climate system, forecast future climate change, and interpret the cultural transformations. Paleoclimate records around the world show manifestations of prominent climate anomalies between 6000 and 5000 calibrated years before present (cal BP). However, a comprehensive review of these anomalies remains unavailable in China. In this article, we collected, compiled, and analyzed proxy climate evidence from 49 sites recorded by a variety of natural archives, including lacustrine sequences, speleothems, peat profiles, an ice core, and marine sediments, to document these changes. Our synthesis results indicate that pronounced climatic anomalies generally characterized by cold and dry conditions occurred during 6000–5000 cal BP, which were associated with weakening of the Asian summer monsoon. However, these anomalies show a lack of absolute synchronicity or equality by various proxy records because of the different proxy sensitivities and/or dating uncertainties. Such 6000–5000 cal BP climatic anomalies also have possible equivalents in proxy records from various regions around the world. Comparison of paleoclimate records with climate forcing time series suggests that both the reduced solar activity and a long-term trend of orbitally-driven insolation change are the main driving mechanisms for these short-lived climate changes. More quantitative and higher-resolution palaeoclimatic reconstructions are needed to fully capture the magnitude, timing, and mechanism of the 6000–5000 cal BP climatic anomalies.