This is getting close to the warming from the LGM [peak of the last ice age] to today (3 - 4 degrees C.), hence we can expect dramatic changes over land, at mid - to high latitudes, in vegetation, mountain glaciers, ice sheets, and sea level. (dotearth.blogs.nytimes.com)
That period coincides with peak of the last ice age, when glaciers covered vast swaths of the northern hemisphere. (sciencedaily.com)
The research drew lessons from paleoclimate studies of the Last Glacial Maximum, the cold peak of the last ice age, that relate to the extent of warmth possible in an era of accumulating greenhouse gases: (dotearth.blogs.nytimes.com)