I do not think it is coincidental that the Little Ice Age followed the largest period of human death in our species' history. This period followed three main events; the Mongol conquest and killing of much of Asia, the Black Death, and the discovery of the Americas with the consequent genocide of ~100 million people in that episode alone.Look up the Ruddiman hypothesis. He argues that forest regrowth lead to a reduction in carbon dioxide concentrations and thus cooling.
Combined, I think we can clearly see that depopulation was a major driver (or was likely a major driver) of the Little Ice Age. This was probably not just due to a reduction in GHG emissions; the changes to continental albedo must also have been fairly dramatic, and an ensuing uptick in forested areas (although relatively short term) would have also provided a massive carbon sink. Think of all the fields/etc that went fallow & sprouted trees after the people who had tended them for several centuries died of plague, Mongols, or smallpox. That is probably at least several percentage points of Earth's total land mass!
My understanding is that, in albedo terms, forests are darker than farmland, and so would cause warming, rather than cooling, were it not for the carbon dioxide effect.
That sound about right. Also forests affect the local hydrological cy le and and cloud formation with an additional cooling effect.