Recent global land cover dynamics and implications for soil erosion and carbon losses from deforestation

Abstract

Abstract Changes in land cover are increasingly affecting land surface properties and provision of ecosystem services. Understanding recent historical land cover changes and their interlinkages with key environmental processes is instrumental to better support strategies for land-use management. The recently released products from the European Space Agency and Copernicus Climate Change Service contain high-resolution (300 m) time series of global land cover maps from 1992 to 2018. This study investigates the land transitions in these products and explores the effects on two key environmental aspects, namely, carbon losses from deforestation and soil erosion rates. We used a powerful server for big data analysis to retain the original spatial resolution of the datasets. We found 722 Mha (5.5% of the total ice-free land surface) of gross land cover changes, which mainly involved transitions to and from forest/agriculture. Cropland gains are 205 Mha and losses 126 Mha (net expansion of 79 Mha). Deforestation occurring in 242 Mha was mainly caused by agricultural expansion, whereas 196 Mha were afforested. Settlements show the largest relative expansion (44 Mha, +210%), of which 67% (29 Mha) occurred at expenses of agricultural land. Deforestation caused 12.3 (7.6/14.2) Gt Carbon losses from below- and aboveground biomass from 2010 to 2018, corresponding to 1.5 (1.0/1.8) Gt Carbon per year. Global agriculture activities have increased total soil erosion of 3.2 Gt and soil erosion rates of 0.22 Mg ha-1 yr-1 in the period 2001-2012, especially in tropical regions. The identified land transitions and changes in key environmental processes reflect a human-dominated Earth system and the indirect effects of climate change on land cover, especially in boreal ecosystems.