Climate Change Research ›› 2019, Vol. 15 ›› Issue (4): 343-351.doi: 10.12006/j.issn.1673-1719.2018.157

• Changes in Climate System • Previous Articles     Next Articles

Uncertainties in the simulation of 1.5℃ and 2℃warming threshold-crossing time arising from model internal variability based on CMIP5 models

Di-Fei JI1,Li LIU1(),Li-Juan LI2,Chao SUN1,Xin-Zhu YU1,Rui-Zhe LI1,Cheng ZHANG1,Bin WANG1,2   

  1. 1 Department of Earth System Science, Tsinghua University, Beijing 100084, China
    2 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;
  • Received:2018-11-09 Revised:2019-01-03 Online:2019-07-30 Published:2019-07-30
  • Contact: Li LIU


Model internal variability has been recognized as an important source of uncertainties of climate simulation results. However, the impact of model internal variability on the uncertainties in the simulation of 1.5℃ and 2℃ warming threshold-crossing time has not been explored to date. In this paper, such impact and the corresponding sensitivity to different future emission scenarios are investigated based on the outputs of Coupled Model Intercomparison Project Phase5 (CMIP5) models. The results show that the effect of internal variability on uncertainties in the simulation of threshold-crossing time is equivalent to that of external forcing. The difference between the threshold-crossing time of model members reaching 1.5℃ or 2℃ global warming is 2-12 years. The influence of internal variability has a clear spatial distribution. Maximum uncertainties are observed at the ocean northern of Eurasia, the area around the Bering Strait, the northeastern North America and the ocean between it and Greenland, and the high latitudes in the Southern Hemisphere. Model internal variability causes greater uncertainties in the low emission scenario than the high emission scenario.

Key words: Coupled Model Intercomparison Project Phase5 (CMIP5), 1.5℃ and 2℃ warming, Threshold-crossing time, Model internal variability

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