Humans have appropriated the productivity of much of the world's vegetation.
They have doubled the rate of the land nitrogen cycle. In many regions
one-third to one-half of river flow is appropriated and returned to the
water cycle through the evaporation pathway. These and other global-scale
actions affect the Earth's energy and biogeochemical cycles in important
ways, with potentially considerable impacts on climate and society.
Understanding the land portion of the Earth system and the prediction of its
future trajectory requires factoring in humans as major agents of change.
In this talk the role of land surface processes in the Earth system will be
discussed and the particular influence of humans will be examined.