Native American global warming?

In terms of long-term impact on the environment, James C. Scott notes that the harnessing of fire and its use over the last 400,000 to alter the landscape might "overwhelm crop and livestock domestication" (p. 38). In fact, Native Americans were such prolifigate users of fire that its "volume in North America was such that when it stopped abruptly, due to the devastating epidemic that came with the Europeans, the newly unchecked growth of forest created the illusion among white settlers that North America was a virtually untouched, primeval forest" (Against the Grain, p. 39). In fact, the cessation of the CO₂ output from such burning may have caused the Little Ice Age!