The Holocene temperature conundrum answered by mollusk records from East Asia

Seasonal biases (the warm-season contribution) of Holocene mean annual temperature (MAT) reconstructions from geological records were proposed as a possible cause of the mismatch with climate simulated temperature. Here we analyze terrestrial mollusk assemblages that best reflect seasonal signals and provide quantitative MAT and four-season temperature records for northern China during the past 20,000 years. The MAT estimated from the seasonal temperatures of a four-season-mean based on mollusks shows a peak during -9000-4000 years ago, followed by a cooling trend. In general, the contribution of summer and winter temperature to MAT is significantly greater than that of spring and autumn temperatures. The relative contribution of each season varies over time and corresponds roughly with the seasonal insolation in each season. This independent evidence from mollusk records from the mid-latitudes of East Asia does not support the Holocene long-term warming trend observed in climate simulations and the seasonal bias explanation.

Automated summary

Analyzing terrestrial mollusk assemblages from northern China, we found that the long-term warming trend and seasonal bias explanation observed in climate simulations during the Holocene does not align with the independent evidence from mollusk records. Summer and winter temperatures have a greater contribution to the mean annual temperature (MAT) than spring and autumn temperatures.