“In a recent article in Science Advances, Ting Zhang and her international team of collaborators present an overview of how several cold-regions catchments are responding to climate change.  The title of the article advertises the topic well: “Shifted sediment-transport regimes by climate change and amplified hydrological variability in cryosphere-fed rivers.”  They first assemble data from four diverse catchments bounding the arid and cold Tarim Basin - catchments that display varying degrees of dominance by modern glaciers, snowfall, and rainfall.  They compare how each of these has changed over the last several decades, focusing in particular on the magnitude and timing of suspended sediment discharge over the runoff season.  Importantly, the authors also present a model that captures the essence of the documented changes.  Rather than leaning on the traditional use of a rating curve that relates suspended sediment discharge to river discharge, they acknowledge the details of how sediment availability changes through the season. This allows them to capture the commonly observed hysteresis in this relationship, in which sediment concentrations are higher during the early part of the runoff season than in the late season for the same river discharge.  They argue that their model is adjustable so that it can be employed in a variety of basins with differing dominant basin characteristics. This is a big step forward from prior approaches, and sets the stage for a more sophisticated approach to how river basins will respond to climate change.”

Robert S Anderson,

Member, National Academy of Sciences

Geological Sciences, University of Colorado Boulder

As the glacier melt in a warmer climate, the proglacial landscapes and river regimes are shifting, posing threats to downstream freshwater ecosystem, riverine infrastructure, and local communities.