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Increasing Alaskan river discharge during the cold season is driven by recent warming

February 7, 2023

Arctic hydrology is experiencing rapid changes including earlier snow melt, permafrost degradation, increasing active layer depth, and reduced river ice, all of which are expected to lead to changes in stream flow regimes. Recently, long-term (>60 years) climate reanalysis and river discharge observation data have become available. We utilized these data to assess long-term changes in discharge and their hydroclimatic drivers. River discharge during the cold season (October–April) increased by 10% per decade. The most widespread discharge increase occurred in April (15% per decade), the month of ice break-up for the majority of basins. In October, when river ice formation generally begins, average monthly discharge increased by 7% per decade. Long-term air temperature increases in October and April increased the number of days above freezing (+1.1 d per decade) resulting in increased snow ablation (20% per decade) and decreased snow water equivalent (−12% per decade). Compared to the historical period (1960–1989), mean April and October air temperature in the recent period (1990–2019) have greater correlation with monthly discharge from 0.33 to 0.68 and 0.0–0.48, respectively. This indicates that the recent increases in air temperature are directly related to these discharge changes. Ubiquitous increases in cold and shoulder-season discharge demonstrate the scale at which hydrologic and biogeochemical fluxes are being altered in the Arctic.

Publication Year 2023
Title Increasing Alaskan river discharge during the cold season is driven by recent warming
DOI 10.1088/1748-9326/acb661
Authors D Blaskey, Joshua C. Koch, M. Gooseff, A. C. Newman, Yang Cheng, Jonathan A. O'Donnell, K Musselman
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Research Letters
Index ID 70240939
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center Water