Hadley cell bias in climate models linked to extratropical eddy stress

Recent theoretical and observational work shows that the Reynolds stresses due to large‐scale extratropical eddies play a key role in determining Hadley cell strength. This implies that errors in the representation of extratropical eddies in climate models could force a bias in the tropical circulation. Here, this hypothesis is assessed using output from 17 coupled climate models, focusing on Northern Hemisphere winter. Inter‐model variability in Hadley cell strength, tropical temperature and tropical humidity is found to be significantly correlated with inter‐model differences in stationary eddy stress. Thus, a significant fraction of the tropical climate bias found in current climate models may be forced from the extratropics.