Currently, about 130 million square kilometres of land on the planet are ice-free, and this is the baseline that’s generally used for calculating human impacts. According to a recent study published by the Geological Society of America, people have “directly transformed” more than half of this land—roughly seventy million square kilometres—mostly by converting it to cropland and pasture, but also by building cities and shopping malls and reservoirs, and by logging and mining and quarrying. Of the remaining sixty million square kilometres, about three-fifths is covered by forest—as the authors
...more
