Multidecadal Temperature Variability in the Community Earth System Model Last Millennium Ensemble

Abstract We investigate the characteristics of inter‐ and multidecadal temperature variability in the Community Earth System Model Last Millennium Ensemble through spatiotemporal spectral analysis of forced and internal fields. We find high spectral density in North Atlantic (NA) and global temperature that is concurrent with periods of high volcanic activity, suggesting a forced origin. There is no evidence in the ensemble of an internally‐generated and time‐persistent signal for Atlantic Multidecadal Variability (AMV), the dominant mode on those timescales. The spatial patterns of low‐frequency variability indicate activity throughout the North Pacific, where signals persist to a greater extent after the forced signal is removed, in contrast with the NA where only the subpolar region associated with deep water formation is active. Subtropical and tropical NA regions are strongly associated with forced responses, suggesting the canonical AMV pattern is comprised of both internal and forced components, with the latter being the main driver.