Representing the present and future release of carbon to rivers in permafrost regions using an earth system model

• Main Author: Bowring, Simon
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris-Saclay, Philippe Ciais, Bertrand Guenet, Ronny Lauerwald
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2019
• Subjects: Active layer; Climate change; Alkalinity; Doc; Rivers; Permafrost; Couche active; Pergélisol; Rivières; Carbone organique dissout (COD); Alcalinité; Changement climatique; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDE.MCG]Environmental Sciences/Global Changes; Arctic; permafrost; pergélisol
• Online Access: https://tel.archives-ouvertes.fr/tel-02297093; https://tel.archives-ouvertes.fr/tel-02297093v2/document; https://tel.archives-ouvertes.fr/tel-02297093v2/file/75066_BOWRING_2019_archivage.pdf

For much of the Pleistocene, regions of the Earth underlain by permafrost have been net accumulators of terrestrially-fixed plant carbon (C), known as organic C, to the extent that in the present day the soils of the northern circumpolar permafrost region alone contain a C mass outweighing that which exists in the modern atmosphere by a factor of over two. At the same time, the rivers of the Arctic permafrost region discharge about 11% of the global volumetric river water flux into oceans, doing so into an ocean (the Arctic) with 1% of global ocean water volume and a very high surface area: volume ratio, making it comparatively sensitive to influxes of terrestrially derived matter. This river flux is sourced from precipitation as either rain or snow, which, upon initial contact with the landscape has the immediate potential to interact with C in one of two ways: Water running over carbonate or silicate –bearing rocks will cause a reaction whose reactant requires the uptake of atmospheric CO2, which is subsequently transported in river water. This ‘inorganic’ C derived from interaction of water, atmosphere and lithosphere thus represents a C storage or ‘sink’ vector. In addition, water interacting with organic matter in tree canopies, litter or soil can dissolve C contained therein, and transfer it via surface and subsurface water flows into rivers, whereupon it may either be metabolised to the atmosphere or exported to the sea. Recent improvements in understanding of terrestrial C dynamics indicate that this hydrologic transfer of organic matter represents the dominant fate of organic carbon, after plant and soil respiration are accounted for. In the context of amplified Arctic anthropogenic warming, the thermal exposure imposed on the permafrost C stock with expectations of enhanced future precipitation point toward substantial shifts in the lateral flux-mediated organic and inorganic C cycle. However, the complex totality of the processes involved make prediction of this shift difficult. Addressing this gap in ...