Because of the ocean's thermal inertia (it takes a long time to warm up), global temperature change caused by the sun's variabilty lags solar irradiance by about 18 months. (skepticalscience.com)
Note that it is essentially meaningless to talk about «trends» that are only 3 years long, because the natural year - to - year variabilty, especially in Antartica, is simply too great. (realclimate.org)
You say this method assumes no role for internal variabilty on the ~ century scale of this study and you have stated that internal variability does play a role on this scale. (judithcurry.com)