Figure 1.5. Estimated changes in net primary productivity (NPP) between 1982 and 1999 derived from independent NDVI data sets from the Global Inventory Modeling and Mapping Studies (GIMMS) and Pathfinder Advanced Very High Resolution Radiometer (AVHRR) Land (PAL). An overall increase in NPP is observed, which is consistent with rising atmospheric CO2 and warming. From Nemani et al., 2003. Reprinted with permission from AAAS.