The Land-surface Processes and eXchanges Dynamic Global Vegetation Model (LPX-DGVM, one of several developments of the Lund–Potsdam–Jena (LPJ) model) is evaluated in terms of its interception component and used to simulate trends in 20th century global relative throughfall from natural vegetation. Mean global annual runoff is estimated to have been reduced by 163 ± 19 km3 year−1 between 1901 and 2006 as a result of biophysical changes controlling throughfall generation. Widespread decreases in relative throughfall of up to −1% are evident between the periods 1901–1953 and 1954–2006, while changes of up to −15% are shown in parts of North America and East Asia. Areas of simulated decrease in relative throughfall often lie in close proximity to areas of increase, reflecting the effects of vegetation shifts.
It is shown that simulated global absolute throughfall has generally increased (because of increasing precipitation) during the studied period, but the curtailing of runoff caused by decreased relative throughfall (as a result of increased fractional plant coverage and possible vegetation shifts) has caused a slight exacerbation of water stress in some regions (including parts of East Asia, North America and the tropics) and increased water supplies in others (for example, other parts of the tropics and northern Russia). This study offers an initial insight into an often overlooked product of climate-induced vegetation changes and attempts to quantify how these responses may contribute to influencing the global freshwater budget and global water resources. Copyright © 2012 John Wiley & Sons, Ltd.