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A decrease in the age of respired carbon from the terrestrial biosphere and increase in the asymmetry of its distribution
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  • Carlos A. Sierra,
  • Gregory R Quetin,
  • Holger Metzler,
  • Markus Müller
Carlos A. Sierra

Corresponding Author:[email protected]

Author Profile
Gregory R Quetin
Department of Geography, University of California, Department of Earth System Science, Stanford University
Holger Metzler
Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Max Planck Institute for Biogeochemistry
Markus Müller
Northern Arizona University, Max Planck Institute for Biogeochemistry


We provide here a model-based estimate of the transit time of carbon through the terrestrial biosphere, since the time of carbon uptake through photosynthesis until its release through respiration. We explored the consequences of increasing productivity versus increasing respiration rates on the transit time distribution and found that while higher respiration rates induced by higher temperature increase the transit time because older carbon is respired, increases in productivity cause a decline in transit times because more young carbon is available to supply increased metabolism. The combined effect of increases in temperature and productivity results in a decrease in transit times, with the productivity effect dominating over the respiration effect. Using an ensemble of simulation trajectories from the Carbon Data Model Framework (CARDAMOM), we obtained time-dependent transit time distributions incorporating 20th century global change. In these simulations, transit time declined over the 20th century, suggesting an increased productivity effect that augmented the amount of respired young carbon, but also increasing the release of old carbon from high latitudes. The transit time distribution of carbon becomes more asymmetric over time, with more carbon transiting faster through tropical and temperate regions, and older carbon being respired from high latitude regions.
28 Mar 2023Submitted to ESS Open Archive
03 Apr 2023Published in ESS Open Archive