Simulated northern hemisphere temperature changes, smoothed with an 11 year running mean, relative to the period AD 950–1250, using the CESM-LME global climate model (data from Otto-Bliesner et al. (2016), see Appendix B for more details of the simulations and data processing). The different panels show simulations with isolated climate factors, while the top panel shows simulations performed with all of the known radiative forcings evolving together. The black line in the top panel shows the observed instrumental northern hemisphere temperature variations with their associated uncertainties (Morice et al., 2012), which match the simulations well. The bottom panel shows a simulation with no changes to the radiative forcings. This quantifies the magnitude of natural internal variability in the simulations in the absence of changes in forcings. Note that the green house gas ensemble mean reaches 1.5C in 2005, while ozone/aerosol reaches −0.85C, and that there are different numbers of ensemble members for each set of factors (see Appendix B). The individual simulations are shown by thin lines and the ensemble mean by the thick lines. Grey shaded regions represent the three LIA Periods, with the darkest interval (LIA3) being the closest in timing to MM.