I go back-and-forth with that data point. Because while that is measurable and does exist, there's also tons of data to the contrary.

Here: researchers argue that the “Genghis-Khan-caused global cooling” idea is overstated: the modeled CO₂ drop from Mongol-era depopulation is extremely small (far below what’s visible in ice cores), natural forces like volcanic eruptions and solar variability overwhelmingly dominate climate shifts of that period, population-loss estimates are highly uncertain, any localized reforestation would have been offset by land-use changes elsewhere, and no clear cooling signal appears in proxy climate records at the exact time of the Mongol conquests.

Excellent question, perhaps we should separate sex and childbirth from sex.