evidence: Anyway, the Younger Dryas ended as suddenly at it began, with temperatures jumping 7° C. Since then, the Earth continued warming up until about 6 thousand years ago — the mid-Holocene thermal maximum. The earth was about 1° or 2° Celsius warmer than today. Since then, it's basically been cooling off — not counting various smaller variations. [...] From 6000 to 2500 years ago things cooled down, with the coolest stretch occuring between 4000 and 2500 years ago: the Iron Age neoglaciation. [...] After this came the Medieval climate optimum, a period from about 1000 to 1300 AD during which European temperatures reached their warmest levels for the last 4000 years.