Human modiﬁcation of the hydrological cycle has profoundly affected the ﬂow of liquid water across the Earth’s land surface. Compared to changes to liquid water flow, alteration of water vapor ﬂows through land-use changes has received comparatively less attention, despite compelling evidence that such alteration can inﬂuence the functioning of the Earth System.
We show that deforestation is as large a driving force as irrigation in terms of changes in the hydrological cycle. Deforestation has decreased global vapor ﬂows from land by 4% (3,000 km3/yr), a decrease that is quantitatively as large as the increased vapor ﬂow caused by irrigation (2,600 km3/yr). Although the net change in global vapor ﬂows is close to zero, the spatial distributions of deforestation and irrigation are different, leading to major regional transformations of vapor-ﬂow patterns [Gordon 2015: 7612].
Gordon, Line J., et al., 2005, Human modification of global water vapor flows from the land surface, PNAS 102:21, http://www.pnas.org/content/102/21/7612