Biases in the Output of Global and Regional Circulation Models
Ehret, U., Zehe, E., Wulfmeyer, V., Warrach-Sagi, K. and Liebert, J. 2012. "Should we apply bias correction to global and regional climate model data?" Hydrology and Earth System Sciences 16: 3391-3404.
For the present study, Ehret et al. provide "a brief overview of state-of-the-art bias correction methods, discuss the related assumptions and implications, draw conclusions on the validity of bias correction and propose ways to cope with biased output of circulation models." In doing so the five German researchers state that (1) "BC methods often impair the advantages of circulation models by altering spatiotemporal field consistency, relations among variables and by violating conservation principles," that (2) "currently used BC methods largely neglect feedback mechanisms, that (3) "it is unclear whether they are time-invariant under climate change conditions," that (4) "applying BC increases agreement of climate model output with observations in hindcasts and hence narrows the uncertainty range of simulations and predictions," but that (5) this is often done "without providing a satisfactory physical justification," which sleight of hand "is in most cases not transparent to the end user."
In light of such problems, Ehret et al. argue that this set of negative consequences of bias correction "hides rather than reduces uncertainty," which they suggest may lead to avoidable forejudging of end users and decision makers." And they thus conclude that BC is often "not a valid procedure."