26 December 2014

Climate Model Simulations of the Observed Early-2000s Hiatus of Global Warming


The slow-down in the rate of global warming in the early-2000s is not evident in the multi-model ensemble average of traditional climate change projection simulations.  However, a number of individual ensemble members from that set of models successfully simulate the early-2000s hiatus when naturally-occurring climate variability involving the Interdecadal Pacific Oscillation (IPO) coincided, by chance, with the observed negative phase of the IPO that contributed to the early-2000s hiatus.  If the recent methodology of initialized decadal climate prediction could have been applied in the mid-1990s using the CMIP5 multi-models, both the negative phase of the IPO in the early 2000s as well as the hiatus could have been simulated, with the multi-model average performing better than most of the individual models.  The loss of predictive skill for six initial years prior to the mid-1990s points to the need for consistent hindcast skill to establish reliability of an operational decadal climate prediction system.

G A Meehl
National Center for Atmospheric Research (NCAR)
Meehl, GA, H Teng, and JM Arblaster.  2014.  "Climate Model Simulations of the Observed Early-2000s Hiatus of Global Warming."  Nature Climate Change 4: 898-902, doi:10.1038/nclimate2357.