Love it how XKCD has the period 2000-2016 global temps rising 100X more as any medieval or roman warming. Or just that it's displayed as more rapid than two 15 year periods before that. But lets take the drawing until 2000 for science sake and still conclude the large error here is that you cannot truly compare resolutions of measurements 1970-2000 (lets say 1080p True Color video) to the lower granularity of the past (like Sinclair spectrum 256 × 192 8bits color per 8x8 squares). Stitching it together as it's one data domain is just plain unadulterated nonsense and deception. And no scientist would ever draw it -- it's reserved for cartoons and evangelists. But surprising how often it's done!
Apart from growing insights on the more global aspects of the warming periods in the last millennia (1), some decent series would be revealed by ice core studies like GRIP, GRIP2, Vostok and EPICA. And sorry, nothing like cartoon warming in there (2) but yes it's understood it's local but at least the series are consistent and resolutions kept constant.