A Satellite-Based Assessment of the Relative Contribution of Hydroclimatic Variables on Vegetation Growth in Global Agricultural and Nonagricultural Regions

Vegetation growth plays a crucial role in the carbon cycle and climate change mitigation. However, the relative contribution of hydroclimatic variables (relative humidity, terrestrial water storage, day and night-time land surface temperatures) on vegetation growth of agricultural and nonagricultural areas at the global scale remains unexplored. Using satellite-based datasets, we examined the changes in Normalized Difference Vegetation Index (NDVI) and the four hydroclimatic variables during 2003–2014. Also, the relative contribution of the four hydroclimatic variables on vegetation growth in agricultural and nonagricultural areas was estimated. A significant (p-value < 0.05) greening has occurred in the agricultural regions of India and Brazil during 2003–2014. Whereas in nonagriculture areas, a considerable greening occurred only in India and China during the 2003–2014 period. Among the four hydroclimatic variables, both day-time and night-time land surface temperature are the significant contributors of vegetation growth in the two-thirds of the global landmass. Terrestrial water storage is a substantial contributor to the vegetation growth in the tropics and subtropics. Night-time land surface temperature is strongly associated with the vegetation growth in the colder regions. The hydroclimatic variables do not explain the considerable amount of the total variance of vegetation growth over the agricultural areas in China, which is due to human agricultural management practices. Generally, the response of hydroclimate variables on vegetation growth in the agricultural and nonagricultural areas has significant implications in many areas, including food security, carbon sequestration, water resource management, and climate change.