claim: Earth’s mean temperature over the last 2,000 years shows two previous periods when temperatures were warmer than they are now; from 1–200 A.D., an epoch called the Roman Warm Period, and more recently the Medieval Warm Period from 900–1100 A.D.
evidence: It is thought that between c. 950 and c. 1100 was the Northern Hemisphere's warmest period since the Roman Warm Period.