Causes of change in 20th century global river discharge

WATCH member Dieter Gerten (The Potsdam Institute for Climate Impact Research - PIK) has contributed to the article Causes of change in 20th century global river discharge which has been published on October 22, 2008 in the Geophysical Research Letters. 

abstract
A global vegetation and hydrology model (LPJmL) was applied to quantify the contributions of changing precipitation, temperature, atmospheric CO2 content, land use and irrigation to worldwide trends in 20th century river discharge (Q). Consistently with observations, Q decreased in parts of Africa, central/southern Asia and south-eastern Europe, and increased especially in parts of North America and western Asia. Based on the CRU TS2.1 climatology, total global Q rose over 1901–2002 (trend, 30.8 km3 a_2, equaling 7.7%), due primarily to increasing precipitation (individual effect, +24.7 km3 a_2). Global warming (_3.1), rising CO2 (+4.4), land cover changes (+5.9) and irrigation (_1.1) also had discernible effects. However, sign and magnitude of trends exhibited pronounced decadal variability and differed among precipitation forcing datasets. Since recent trends in these and other drivers of Q are mainly anthropogenic, we conclude that humans exert an increasing influence on the global water cycle.

Read full article at the GRL website.

Citation
Gerten, D., Rost, S., von Bloh, W., Lucht, W.: Causes of change in 20th century global river discharge.
Geophys. Res. Lett. 35, L20405, doi:10.1029/2008GL035258.

Dieter Gerten has also contributed to the WATCH Technical Report (deliverable D5.2.1): Uncertainty in water budgets of the 20th century due to representation of impact of CO2 enrichment (which is not yet publicly available).

Gerten, D., Rost, S., von Bloh, W., Lucht, W (Potsdam Institute for Climate Impact Research, Potsdam, Germany)
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Friday 24 April 2009