A perfectly preserved tunic from Roman times uncovered from melting glacier proves the climate was warmer then. A Limerick.

The tunic at Lomseggen pass

a garment of very high class

got preserved in the ice

glaciers grew, then demise

the climate change sure shows pizzazz

This tunic was made in the third or fourth century A.D. It is made of wool, and like all good tunics of that time it was never washed. The original sheep tallow in the wool made it a very good water repellent, so it was warm enough to wear when going over the short pass in snow in the winter. The oldest artifacts found, stone arrow points are about 6000 years old

and the newest are from viking times around 1200 A.D.

The Landbreen Glacier in central Norway grew, and from about 1400 to 2000 A.D. the pass was under the ice pack of the glacier. This proves that the climate was warmer  in roman and viking times than it was up till the 20th century. To prove this point we can see the temperature records from the Greenland icecap, at about the same latitude. (The temperature is in degree Celsius)

As we can see, there is a negative correlation between CO2 and temperature. This is counter-intuitive, but far more important than the amount of CO2 to affect the climate is the amount of clouds, the amount of snow they contain and when and where they occur. It turns out that clouds are the main temperature regulator for the climate, and we are eventually and slowly entering another ice-age. The recent rise in CO2 from 280 ppm to 405 ppm will delay the onset of the next ice age, surely arriving in the next 10000 years. Right now we are almost back to the conditions of the Medieval warm period, but still much below the ideal conditions during the Roman warm period. The climate is getting better.