In the last 250 years there has been a human population explosion. A lot of things have accompanied that which are plausibly more relevant than CO2.

For example, more land than ever has had to be brought under cultivation. If you have ever flown in a small plane over a ploughed field on a sunny day, you will experience a huge updraft there because of the increased conversion of optical energy to heat.

Related to the above comment, I think it would be worth investigating whether the halving of the human population of Eurasia by the Black Death, in the 14th century, contributed to the sudden end to the medieval warming and onset of the little ice age shortly afterwards?