Read here. Peer-reviewed research documents the glacier retreat that happened during the Medieval Warming period for the Antarctica peninsula area. Despite Climategate scientists and alarmists claims, this evidence confirms that Antarctica (and the Southern Hemisphere) experienced the climate change of the Medieval era.
"Hall et al. examined organic-rich sediments exposed by recent retreat of the Marr Ice Piedmont on western Anvers Island, where glaciers have been undergoing considerable retreat in response to the well-documented warming of the Antarctic Peninsula..... This work revealed, in their words, that "peat from the overrun sediments dates between 707 ± 36 and 967 ± 47 cal. yr B.P.," which led them to conclude that "ice was at or behind its present position at ca. 700-970 cal. yr B.P," which they interpret as implying that "the present state of reduced ice on the western Antarctic Peninsula is not unprecedented," which means that this period was at least as warm as, or likely even warmer than, the peak warmth of the Current Warm Period."