Proxy global assessment of land degradation

Abstract Land degradation is always with us but its causes, extent and severity are contested. We define land degradation as a long‐term decline in ecosystem function and productivity, which may be assessed using long‐term, remotely sensed normalized difference vegetation index (NDVI) data. Deviation from the norm may serve as a proxy assessment of land degradation and improvement – if other factors that may be responsible are taken into account. These other factors include rainfall effects which may be assessed by rain‐use efficiency, calculated from NDVI and rainfall. Results from the analysis of the 23‐year Global Inventory Modeling and Mapping Studies (GIMMS) NDVI data indicate declining rain‐use…