Rome was at its peak during a warm period.
The Dark Ages were a cold period.
Leif Erickson sailed to the New World during a warm period -- Britain had vineyards then.
The Little Ice Age last from about 1500 to 1850.
Are we getting warmer now? [shrug] I think opinions differ -- but the key concept is that Climate does change. It's not our fault, and we can't "fix it". We're just along for the ride.
There is a reason the AGW proponents like to use 150 years ago as the benchmark evidence that we are so much warmer today. That was the end of the last little ice age, so ANYTHING is warmer than that!