EGU22-7037, updated on 28 Mar 2022
https://doi.org/10.5194/egusphere-egu22-7037
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Destabilizing the Earth’s thermostat: Riverine alkalinity responses to climate change

Nele Lehmann1,2, Tobias Stacke1,3, Sebastian Lehmann4, Hugues Lantuit2,5, John Gosse6, Chantal Mears1, Jens Hartmann7, and Helmuth Thomas1
Nele Lehmann et al.
  • 1Institute of Carbon Cycles, Helmholtz-Zentrum Hereon, Geesthacht, Germany (nele.lehmann@hereon.de)
  • 2Geosciences Department, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany
  • 3now at Max Planck Institute for Meteorology, Hamburg, Germany
  • 4Private investigator, Buchholz in der Nordheide, Germany
  • 5Institute for Geosciences, University of Potsdam, Potsdam, Germany
  • 6Department of Earth and Environmental Sciences, Dalhousie University, Halifax, Canada
  • 7Institute for Geology, University Hamburg, Hamburg, Germany

Alkalinity generation from rock weathering is thought to modulate the Earth’s climate at geological time scales. Here, we use global alkalinity data paired with consistent measurements of erosion rates to develop an empirically-based model for riverine alkalinity concentration, demonstrating the impact of both erosion (i.e. erosion rate) and climate (i.e. temperature) on alkalinity generation, globally. We show that alkalinity generation from carbonate rocks is very responsive to temperature and that the weathering flux to the ocean will be significantly altered by climate warming as early as the end of this century, constituting a sudden feedback of ocean CO2 sequestration to climate. While we anticipate that climate warming under a low emissions scenario will induce a reduction in terrestrial alkalinity flux for mid-latitudes (-1.3 t(bicarbonate) a-1 km-2) until the end of the century, resulting in a temporary reduction in CO2 sequestration, we expect an increase (+1.6 t(bicarbonate) a-1 km-2) under a high emissions scenario, causing an additional short-term CO2 sink at decadal timescales.

How to cite: Lehmann, N., Stacke, T., Lehmann, S., Lantuit, H., Gosse, J., Mears, C., Hartmann, J., and Thomas, H.: Destabilizing the Earth’s thermostat: Riverine alkalinity responses to climate change, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7037, https://doi.org/10.5194/egusphere-egu22-7037, 2022.

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