National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2018

Simulated impact of glacial runoff on CO2 uptake in the coastal Gulf of Alaska

Pilcher, D.J., S.A. Siedlecki, A.J. Hermann, K.O. Coyle, J.T. Mathis, and W. Evans

Geophys. Res. Lett., 45(2), 880–890, doi: 10.1002/2017GL075910 (2018)

The Gulf of Alaska (GOA) receives substantial summer freshwater runoff from glacial meltwater. The alkalinity of this runoff is highly dependent on the glacial source and can modify the coastal carbon cycle. We use a regional ocean biogeochemical model to simulate CO2 uptake in the GOA under different alkalinity-loading scenarios. The GOA is identified as a current net sink of carbon, though low-alkalinity tidewater glacial runoff suppresses summer coastal carbon uptake. Our model shows that increasing the alkalinity generates an increase in annual CO2 uptake of 1.9–2.7 TgC/yr. This transition is comparable to a projected change in glacial runoff composition (i.e., from tidewater to land-terminating) due to continued climate warming. Our results demonstrate an important local carbon-climate feedback that can significantly increase coastal carbon uptake via enhanced air-sea exchange, with potential implications to the coastal ecosystems in glaciated areas around the world.

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