From 1982 to 2016, the world's tree coverage actually increased by 7.1%. Per a 2018 paper in journal Nature: "Here we analyze 35 years' worth of satellite data and provide a comprehensive record of global land-change dynamics during the period 1982-2016. We show that ... tree cover has increased by 2.24 million sq. km (+7.1% relative to the 1982 level)."