Smith, S. J., Wigley, T. M. L., Meinshausen, M., & Rogelj, J. (2014). Questions of bias in climate models. Nature Climate Change, 4, 741-742. doi:10.1038/nclimate2345
Shindell has contributed to the debate on estimating the equilibrium climate sensitivity (ECS) by noting that the transient response to external forcing depends on the spatial distribution of the forcing; forcings over land lead to more rapid warming than similar forcings over the oceans. He sugg... Show moreShindell has contributed to the debate on estimating the equilibrium climate sensitivity (ECS) by noting that the transient response to external forcing depends on the spatial distribution of the forcing; forcings over land lead to more rapid warming than similar forcings over the oceans. He suggests that the omission of spatial forcing details will lead simple models to give biased results for the transient climate response. Shindell chooses to reference only two previous studies as examples of analyses affected by such a bias, stating for the latter that "such biases lead to underestimates of aerosol impacts in [the] calculations". Shindell's criticism of these particular results is incorrect. Both of these papers use the Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC), which has always accounted for the effect highlighted by Shindell. MAGICC uses differential land–ocean and North-South hemisphere forcings and incorporates different land and ocean feedback factors. Thus, while Shindell has quantified this effect for some Coupled Model Intercomparison Project Phase 5 (CMIP5) models, knowledge of the effect per se is not new and it has always been accounted for in MAGICC. Show less