Linkages Between Global Vegetation and Climate

A monthly global 1 degree by 1 degree data set from 1982 until 1990 was derived from data collected by the Advanced Very High Resolution Radiometer on board the NOAA 7, 9, and 11 satellites. This data set was used to study the interactions between variations in climate and variations in the "greenness" of vegetation. Studies with the Colorado State University atmospheric general circulation model coupled to the Simple Biosphere model showed a large sensitivity of the hydrological balance to changes in vegetation at low latitudes. The depletion of soil moisture as a result of increased vegetation density provided a negative feedback in an otherwise positive association between increased vegetation, increased evaporation, and increased precipitation proposed by Charney and coworkers. Analysis of climate data showed, at temperate to high latitudes, a positive association between variation in land surface temperature, sea surface temperature and vegetation greenness. At low latitudes the data indicated a positive association between variations in sea surface temperature, rainfall and vegetation greenness. The variations in mid- to high latitude temperatures affected the global average greenness and this could provide an explanation for the increased carbon uptake by the terrestrial surface over the past couple of decades.