Global decadal changes in NDVI and its relationships to climate variables

Global decadal trends of annual and seasonal NDVIs along with the correlation between interannual NDVI variation and climatic variables were analyzed using Pathfinder AVHRR Land (PAL) NDVI and observed climate data sets from 1982 to 1990. Interannual NDVI variations were significantly correlated with temperature variations in the northern middle and high latitude areas from spring to autumn, and both temperature and precipitation variations in the northern and southern semiarid regions. Comparison with the global NDVI trend indicates that the NDVI increase in the northern middle and high latitudinal zones was related to temperature rise, and the NDVI decrease in southern semiarid regions was due to precipitation decrease in that period. Although the cause of NDVI increases in the equatorial regions is unclear, mixed effects of forest regrowth, deforestation and biospheric fertilization effects might have some impacts on the NDVI trend.