Atmospheric Temperature Changes in CMIP-5 Simulations of Forced and Unforced Climate Change
Abstract
We provide a preliminary analysis of surface and atmospheric temperature trends in CMIP-5 pre-industrial control runs and in simulations of historical temperature change. Our focus is on: 1) Comparing the detailed latitude-altitude structure of simulated and observed temperature trends over the satellite era; 2) Using observational temperature data and model control runs to estimate signal-to-noise (S/N) ratios, which provide information on the size of observed temperature changes relative to the amplitude of unforced variability; 3) Examining the timescale-dependence of S/N behavior, and the S/N properties of surface, tropospheric, and stratospheric temperature changes; 4) Assessing whether observational estimates of surface and atmospheric temperature trends are in closer agreement with CMIP-3 or CMIP-5 simulations of historical climate change; and 5) Considering whether CMIP-5 models systematically underestimate the amplitude of observed temperature variability on decadal timescales. Relative to CMIP-3, the CMIP-5 models incorporate improvements in many aspects of the physics of the coupled atmosphere-ocean system. The CMIP-5 simulations of historical climate change are also likely to include better and more complete estimates of changes in key external forcings. Because of these model and forcing improvements, the expectation is that the multi-model average temperature changes in CMIP-5 will be closer to observations. Whether this expectation is realistic is currently difficult to determine, since the CMIP-5 archive is only sparsely populated with the relevant historical simulations. A more definitive answer to the question "Do CMIP-5 models provide better simulations of historical temperature change?" should be available by the time of the Fall AGU Meeting.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMGC54A..05S
- Keywords:
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- 1610 GLOBAL CHANGE / Atmosphere;
- 1616 GLOBAL CHANGE / Climate variability;
- 1626 GLOBAL CHANGE / Global climate models