EAS Fall 2017 Seminar Series Presents: Dr. Jiafu Mao, Oak Ridge National Laboratory

The land greening, characterized by the change of vegetation indices, has been documented to significantly increase over the past 3 decades, especially in the northern extratropical land surface. Drivers of this enhanced vegetation growth have been extensively investigated using multiple estimates from observed and modeled datasets and various statistical methods. 

Spatialtemporal changes of the main climate drivers (e.g., temperature, precipitation and radiation) have been widely accessed to modulate the variation in vegetation growth. The combined anthropogenic effects, particularly the rising atmospheric concentrations of well-mixed GHGs, was recently clearly identified as the dominant factor controlling this observed land greening. 

On the other hand, the enhancement of vegetation activity can potentially accelerate the photosynthetic removal of atmospheric CO2 and decrease the surface air temperature causing a negative forcing on climate system. Also, through the complicated biophysical feedbacks (e.g., the increased evapotranspiration and absorption of solar radiation), the land greening can intensify or diminish negative climate forcing induced via its biogeochemical feedbacks. 

Future vegetation growth and feedbacks, however, remain to be determined because of nonlinear human-ecosystem-climate interactions under global warming.