Ghost of a flea

What stopped it has been the activity of humans, both ancient and modern, argue the scientists. Over the last 8,000 years carbon dioxide levels in the atmosphere have gradually risen, when previous trends indicated that it should have dropped. Methane, another greenhouse gas, had also increased instead of fallen. The unexpected trends could be explained by massive early deforestation in Eurasia, rice farming in Asia, the introduction of livestock, and the burning of wood and plant material, all of which led to an outpouring of greenhouse emissions.