Global pattern of trends in streamflow and water availability in a changing climate

Abstract

Water availability on the continents is important for human health, economic activity, ecosystem function and geophysical processes. Because the saturation vapour pressure of water in air is highly sensitive to temperature, perturbations in the global water cycle are expected to accompany climate warming. Regional patterns of warming-induced changes in surface hydroclimate are complex and less certain than those in temperature, however, with both regional increases and decreases expected in precipitation and runoff. Here we show that an ensemble of 12 climate models exhibits qualitative and statistically significant skill in simulating observed regional patterns of twentieth-century multidecadal changes in streamflow. These models project 10-40% increases in runoff in eastern equatorial Africa, the La Plata basin and high-latitude North America and Eurasia, and 10-30% decreases in runoff in southern Africa, southern Europe, the Middle East and mid-latitude western North America by the year 2050. Such changes in sustainable water availability would have considerable regional-scale consequences for economies as well as ecosystems.

Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

“…Most large-scale studies, which explore hydrological impact of climate change, compare simulated and observed annual river flow to assess model fitness as a basis for projections (e.g. Arnell, 2003;Milly et al, 2005;Hagemann et al, 2013;Schewe et al, 2014). Other studies also focus on low water availability and include minimum flow or flow deficits to investigate future drought (e.g Feyen and Dankers, 2009;Forzieri et al, 2014).…”

Mapping (dis)agreement in hydrologic projections

“…Models are needed to provide quantitative projections of how water resources will be affected by climate change. These projections remain, however, uncertain (Milly et al, 2005;Clark et al, 2016). To account for this uncertainty, quantitative hydrologic storylines, in which key features of climate change impact are represented, can guide water managers in developing dynamic policy pathways (Haasnoot et al, 2013).…”

Defining high-flow seasons using temporal streamflow patterns from a global model

“…To specifically address flood disasters from a global perspective, understanding of global-scale flood processes and streamflow variability is important (Dettinger and Diaz, 2000;Ward et al, 2014). In recent decades, studies have investigated global-scale streamflow characteristics using observed streamflow from around the world McMahon, 1992;McMahon et al, 2007;Peel et al, 2001Peel et al, , 2004Poff et al, 2006;Probst and Tardy, 1987) and modeled streamflow from global hydrological models McCabe and Wolock, 2008;Milly et al, 2005;Ward et al, 2013Ward et al, , 2014 to investigate ungauged and poorly gauged basins (Fekete and Vörösmarty, 2007). Despite this broad attention to annual streamflow and its connections to global climate processes and precursors, there has been relatively little attention paid to the intra-annual timing of streamflow, emphasizing the need for analysis of seasonal streamflow patterns to further improve understanding of large-scale hydrology and atmospheric behaviors in the main (flood) streamflow season globally (Dettinger and Diaz, 2000).…”