Before revision: According to the Special Report on Climate Change and Land of the Intergovernmental Panel on Climate Change : "About a quarter of the Earth's ice-free land area is subject to human-induced degradation (medium confidence).
After revision: According to the Special Report on Climate Change and Land of the Intergovernmental Panel on Climate Change , "About a quarter of the Earth's ice-free land area is subject to human-induced degradation (medium confidence).