" Erle Ellis of the University of Maryland and Navin Ramankutty of McGill, argue that thinking in terms of biomes defined by climate and vegetation—temperate grasslands, say, or boreal forests—no longer makes sense. Instead, they divide the world up into “anthromes.” There is an “urban” anthrome that stretches over five hundred thousand square miles, an “irrigated cropland” anthrome (a million square miles), and a “populated forest” (four and a half million square miles). Ellis and Ramankutty count a total of eighteen “anthromes,” which together extend over thirty-nine million square miles. "

― Elizabeth Kolbert , The Sixth Extinction: An Unnatural History