We assessed the impacts of climate change on river flows and
water temperatures globally by using the physically based VICRBM
modelling framework forced by an ensemble of biascorrected
GCM output. The largest predicted water temperature
rises are for the US, Europe and eastern China, where water
temperature rises are exacerbated by declines in low flows. For
strongly seasonal rivers (with highest water temperatures during
the low flow period), a substantial fraction (up to 26%) of the
increases in high water temperatures is attributable indirectly to
declines in low flow. Therefore, both the direct impacts of
atmospheric warming and indirect effects of river flow changes
are important to include in assessments of climate change impacts
on river temperatures. The combination of projected rises in river
temperature and decreases in river flow may have important
consequences for water quality, freshwater ecosystems and
human water uses.