Global climate change has attracted increasing attentions in recent years as a challenge facing human life. Accurately
mapping, quantifying and monitoring changes in the physical characteristics of vegetation cover is a key element in the
study of global climate change.
The normalized difference vegetation index (NDVI) has been used extensively in ecosystem and climate monitoring.
This paper examined vegetation change over the last 27 years (1981-2007) over Continental US. Using history of the
values of the normalized difference vegetation index (NDVI) which is extracted from satellite sensor data acquired by
the National Oceanic & Atmospheric Administration - Advanced Very High Resolution Radiometer (NOAA-AVHRR),
long time series of satellite-derived vegetation index has been studied showing the increasing trend of vegetation index
over Continental US from 1981 to 2007. The results demonstrated that the change of NDVI shows an increasing trend
which might be induced by the global warming. The comparison of the land cover data in 1981 and 2001 validated the
uptrend of NDVI.