October 12, 2021
Increasing Freshwater and Dissolved Organic Carbon Flows to Northwest Alaska’s Elson Lagoon
Changes linked to increasing precipitation and the effects of warming and thawing soils
Mounting evidence shows that climate change is impacting flows of water and carbon in Arctic rivers. In northern Alaska, field sampling data is too limited to differentiate new from normal baseline conditions. This research applied numerical modeling to investigate climate changes impacting a coastal lagoon over recent decades. The simulation reveals significant increases in freshwater and dissolved organic carbon exports. Large increases in subsurface freshwater and carbon flows during autumn are congruent with expected impacts from sea ice losses across the nearby Beaufort and Chukchi Seas.
Increased freshwater export has implications for salinity and other components of the lagoon aquatic environment. Increased runoff in late summer or autumn could support increasing biological production in the lagoons during a time when nutrient levels are lower, compared to late spring. These results highlight the need for dedicated measurement programs of climate change impacts on coastal zone processes in Arctic regions.
This study applied numerical modeling to investigate trends in freshwater and dissolved organic carbon (DOC) exports from land to Elson Lagoon in Northwest Alaska over the period 1981–2020. The model simulation reveals significant increases in surface, subsurface (suprapermafrost), and total freshwater exports. Findings included significant increases in surface and suprapermafrost DOC production and export. The largest changes in subsurface components are noted in September, which has experienced a 50% increase in DOC export from suprapermafrost flow. Direct coastal suprapermafrost freshwater and DOC exports in late summer more than doubled between the first and last five years of the simulation period, with a large anomaly in September 2019 representing a more than fourfold increase over September direct coastal export during the early 1980s. The changes are linked to increasing precipitation, particularly during summer-autumn, and the effects of warming and thawing soils. The largest freshwater and DOC increases occur in autumn, consistent with significant losses in sea ice across the nearby Beaufort and Chukchi Seas, in turn connected to Earth’s warming climate.
University of Massachusetts Amherst
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
This work was funded by the U.S. Department of Energy’s (DOE) Office of Biological and Environmental Research (grant no. DE-SC0019462); the National Aeronautics and Space Administration (grant no. 80NSS-C19K0649); and the National Science Foundation’s (NSF) Division of Polar Programs (grant no. NSF-OPP-1656026).
Rawlins, M.A., et al. "Modeling Terrestrial Dissolved Organic Carbon Loading to Western Arctic Rivers." Journal of Geophysical Research: Biogeosciences 126 e2021JG006420 (2021). https://doi.org/10.1029/2021JG006420.
Rawlins, M.A. "Increasing Freshwater and Dissolved Organic Carbon Flows to Northwest Alaska’s Elson lagoon." Environmental Research Letters 16 105014 (2021). https://doi.org/10.1088/1748-9326/ac2288.