Rising river flows throughout the twenty-first century in two Himalayan glacierized watersheds

Greater Himalayan glaciers are retreating and losing mass
at rates comparable to glaciers in other regions of the
world1–5
. Assessments of future changes and their associated
hydrological impacts are scarce, oversimplify glacier dynamics
or include a limited number of climate models6–9
. Here, we
use results from the latest ensemble of climate models in
combination with a high-resolution glacio-hydrological model
to assess the hydrological impact of climate change on two
climatically contrasting watersheds in the Greater Himalaya,
the Baltoro and Langtang watersheds that drain into the Indus
and Ganges rivers, respectively. We show that the largest
uncertainty in future runoff is a result of variations in projected
precipitation between climate models. In both watersheds,
strong, but highly variable, increases in future runoff are
projected and, despite the different characteristics of the
watersheds, their responses are surprisingly similar. In both
cases, glaciers will recede but net glacier melt runoff is on a
rising limb at least until 2050. In combination with a positive
change in precipitation, water availability during this century is
not likely to decline. We conclude that river basins that depend
on monsoon rains and glacier melt will continue to sustain the
increasing water demands expected in these areas10
.