evidence: The Vikings’ arrival and departure from Greenland was not heavily influenced by the so-called medieval warm period, according to new research that casts doubt that the climatic change was a global phenomenon. [...] But new analysis of glaciers in Greenland shows that there was no significant change in their extent during the medieval warm period, suggesting that it remained relatively cold throughout the Viking colonisation of Greenland. [...] Previous research has painted a complex picture of the climate of Greenland during Norse occupation. Study of an ice core extracted in 2011 shows temperatures dropped as Vikings arrived, with warming intervals during their stay. A separate study suggests it may have been warmer when the Norse arrived but then the climate started cooling in 1160, before the start of the little ice age.