Last glacial maximum permafrost in China from CMIP5 simulations

摘要

The distributions of frozen ground and active layer thickness (ALT) during the last glacial maximum (LGM) and pre-industrial periods in China were investigated using Coupled Model Intercomparison Project Phase 5 (CMIP5) model experiments. Compared to the pre-industrial period, the LGM climate was similar to 5 degrees C colder and featured significantly higher freezing indices on the Tibetan Plateau and in Northeast China. Frozen ground expanded widely in the LGM. The extents of permafrost and seasonally frozen ground in China were 4.11 x 10(6) km(2) and 4.97 x 10(6) km(2), respectively, which are 2.42 x 10(6) km(2) larger and 1.45 x 10(6) km(2) smaller, respectively, than the pre-industrial levels. Moreover, the colder climate and longer duration also resulted in LGM ALT values that were 13 m less than the pre-industrial values in the permafrost areas common to both periods. Altitudinal permafrost was present mainly on the Tibetan Plateau and adjacent mountains in West China between 28 degrees N and 41 degrees 30'N and covered an area of similar to 2.63 x 10(6) km(2). Latitudinal permafrost was present mainly in Northeast China and occupied an area of 1.48 x 10(6) km(2). The southern limit of latitudinal permafrost was located similar to 10 degrees of latitude farther south during the LGM than during the pre-industrial period. The LGM simulation results agree reasonably well with previous reconstructions, with the exception of an underestimation in the permafrost extent. Although relatively high-level disagreement exists between the models in terms of the exact locations of the southern limits, the ensemble average is still able to represent the large-scale spatial pattern of frozen ground remarkably well. (C) 2016 Elsevier B.V. All rights reserved.