So I read the first link which can't even quote the source of the report but instead quoted the site Mother Nature Network....a site the has citing problems of it's own, but anyways.
I found the orginal article
War, Plague No Match for Deforestation in Driving CO2 Buildup and no where did it say killing people is the way to go. It's not saying kill 40 million people.....it also doesn't say that the earth cooled down because Genghis Khan killed people. It is saying that humans have contributed to climate change before the industrial revolution.
Also the 700 million tons of carbon that was "scrubbed" from the atmosphere was not due to the death of people. The article doesn't even touch on that point. It states "But in the case of the Mongol invasions, which had the biggest impact of the four events studied, re-growth on depopulated lands stockpiled nearly 700 million tons of carbon absorbed from the atmosphere."
They are discussing deforestation and regrowth of the forests, not mass murder.
Learn to do research. If you want to believe that everyone is out to get you, fine. But bring compelling arguments not crap that is so taken out of context a ten-year-old would be asking questions about it's validity. Arguing for something is NOT copying and pasting a link it's using your own damn words to get your point across and citing when needed.
