The most important climate driver in my Climate Theory is Albedo
Albedo is the reflecting power of a surface – The Earth surface includes Land, Water, Ice and Clouds.
The areas of most interest are land in North America, Europe and Asia, where more or less Snow and Ice can be found from year to year and Antarctica and the big ice donut around Antarctica, Ice on land in South and, Especially, Clouds everywhere.
More Clouds and More Ice Extent – Higher Albedo
Less Clouds and Less Ice Extent – Lower Albedo
Most people keep Albedo for Earth as a constant = ~ 0.3
That is likely correct now, and during this phase of the Roman and Medieval Warm periods.
The Albedo of Earth was higher during the Little Ice Age and during all other Colder periods of the past ten thousand years and the past 800 thousand years.
Consensus People say this difference is a result. I conclude this difference is the means Earth uses to regulate temperature in tight bounds that are wonderfully different and better.