18 July 2016

Identifying Human Influences on Atmospheric Temperature

Trends in lower tropospheric temperature over January 1979 to December 2011 in satellite observations (top 2 panels) and in CMIP-5 models. For further details, refer to Fig. 4 in Santer et al. (2013a)
Science

Objective

  • Performs the first multi-model fingerprint study with CMIP-5 simulation output and satellite measurements of stratospheric and tropospheric temperature change

Main scientific points

  • Clearest evidence to date of a human influence on atmospheric temperature
  • Satellite data and CMIP-5 simulations of historical climate change show similar geographical patterns of tropospheric warming and lower stratospheric cooling
  • Sustained, global-scale tropospheric warming and stratospheric cooling cannot be explained by natural internal climate variability
Impact
  • Shows that the identification of a human-caused signal in atmospheric temperature is robust to uncertainties in models and data
  • Maintains DOE’s leadership in fingerprint research
Summary

We find some of the clearest evidence to date of a discernible human influence on atmospheric temperature. Satellite data and computer model simulations of historical climate change show common patterns of pronounced warming of the troposphere and cooling of the lower stratosphere. In the model simulations, these changes are mainly caused by human factors. We show that sustained, global-scale tropospheric warming and lower stratospheric cooling cannot be explained by natural climate variability. Our results are robust to current uncertainties in models and satellite observations.  

Contact
Benjamin Santer
Lawrence Livermore National Laboratory (LLNL)
Publications
Santer, BD, JF Painter, CA Mears, C Doutriaux, P Cadwell, JM Arblaster, PJ Cameron-Smith, et al.  2013.  "Identifying Human Influences on Atmospheric Temperature."  Proceedings of the National Academy of Sciences 110(1): 26-33.  https://doi.org/10.1073/pnas.1210514109.