Streamflow shifts with declining snowfall

Abstract

arising from: J. Han et al. Nature https://doi.org/10.1038/s41586-024-07299-y (2024).

Climate warming acts to decrease the fraction of precipitation falling as snow (the snow fraction, f_s), affecting water resources in snowmelt-fed regions by typically shifting streamflow timing to earlier in the year^1,2,3. Han et al.⁴ recently called for revision of the ‘less snow equals earlier streamflow’ paradigm, because their analysis indicated that although the paradigm holds for average annual high-snow-fraction catchments (\(\bar{{f}_{{\rm{s}}}}\) > 0.5), lower-snow-fraction catchments (0.1 < \(\bar{{f}_{{\rm{s}}}}\) < 0.4) experience later seasonal streamflow as snow fractions reduce. Here we use results generated by Han et al.⁴ to show that trends towards earlier streamflow are instead dominant across the entire defined range of low to high snow-fraction catchments (0.1 < \(\bar{{f}_{{\rm{s}}}}\) < 1), supporting the paradigm. Furthermore, we use catchment climatological data to demonstrate that comparing streamflow timing between low- and high-snow-fraction years, as used by Han et al.⁴, is a misleading way to study the effects of climate-warming-induced snow changes and subsequent streamflow seasonality.