07 Jun 2022
07 Jun 2022
Status: this preprint is open for discussion.

Global and Northern-High-Latitude Terrestrial carbon sinks in the 21st century from CMIP6 experiments

Han Qiu1,2, Dalei Hao2, Yelu Zeng1, Xuesong Zhang3, and Min Chen1,4 Han Qiu et al.
  • 1Department of Forest and Wildlife Ecology, University of Wisconsin-Madison
  • 2Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA
  • 3USDA-ARS Hydrology and Remote Sensing Laboratory, Beltsville, MD 20705-2350 USA
  • 4Center for Climatic Research, Nelson Institute, University of Wisconsin-Madison

Abstract. Climate warming is accelerating the changes in the global terrestrial ecosystems and particularly those in the northern high latitudes (NHL), and rendering the land-atmosphere carbon exchange highly uncertain. The Coupled Model Intercomparison Project Phase 6 (CMIP6) employs the most updated climate models to estimate terrestrial ecosystem carbon dynamics driven by a new set of socioeconomic and climate change pathways. By analyzing the future (2015–2100) carbon fluxes estimated by ten CMIP6 models, we quantitatively evaluated the projected magnitudes, trends and uncertainties of global and NHL carbon fluxes under four scenarios plus the role of NHL in the global terrestrial ecosystem carbon dynamics. Overall, the models suggest that the global and NHL terrestrial ecosystems will be consistent carbon sinks in the future, and the extent of the carbon sinks is projected to be larger under scenarios with higher radiative forcing. By the end of this century, the models by average estimate the NHL net ecosystem productivity (NEP) as 0.54±0.77, 1.01±0 .98, 0.97±1.62, and 1.05±1.83 PgC/yr under SSP126, SSP245, SSP370 and SSP585, respectively. The uncertainties are not substantially reduced compared with earlier results, e.g., the Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP). Although NHL contributes a small fraction of the global carbon sink (~13 %), the relative uncertainties of NHL NEP are much larger than the global level. Our results provide insights into future carbon flux evolutions under future scenarios and highlight the urgent need to constrain the large uncertainties associated with model projections for making better climate mitigation strategies.

Han Qiu et al.

Status: open (until 19 Jul 2022)

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  • RC1: 'Comment on egusphere-2022-417', Xu Lian, 22 Jun 2022 reply

Han Qiu et al.


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Short summary
The carbon cycling in terrestrial ecosystems is complex. In our analyses, we found both the global and the northern high latitude (NHL) ecosystems will continue to be carbon sinks in the next few decades under four global change scenarios but with large uncertainties. NHL ecosystems will experience faster climate warming but steadily contribute a small fraction to the global carbon sink. However, the relative uncertainty of NHL carbon sink is much larger than the global level values.