Changes in interannual climate sensitivities of terrestrial carbon fluxes during the 21st century predicted by CMIP5 Earth System Models

Yongwen Liu (1) , Tao Wang (2) , Mengtian Huang (1) , Yitong Yao (1) , Philippe Ciais (3, 4) , Shilong Piao (1)

1 Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences
2 CAS - Chinese Academy of Sciences [Beijing]
3 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
4 ICOS-ATC - ICOS-ATC

Terrestrial carbon fluxes are sensitive to climate change, but the interannual climate sensitivity of the land carbon cycle can also change with time. We analyzed the changes in responses of net biome production (NBP), net primary production (NPP), and heterotrophic respiration (Rh) to interannual climate variations over the 21st century in the Earth System Models (ESMs) from the Coupled Model Intercomparison Project 5. Under Representative Concentration Pathway (RCP) 4.5, interannual temperature sensitivities of NBP (γ Temp NBP), NPP (γ Temp NPP), and Rh (γ Temp Rh) remain relatively stable at global scale, yet with large differences among ESMs and spatial heterogeneity. Modeled γ Temp NPP and γ Temp Rh appear to increase in parallel in boreal regions, resulting in unchanged γ Temp NBP. Tropical γ Temp NBP decreases in most models, due to decreasing γ Temp NPP and relatively stable γ Temp Rh. Across models, the changes in γ Temp NBP can be mainly explained by changes in γ Temp NPP rather than changes in γ Temp Rh , at both global and regional scales. Interannual precipitation sensitivities of global NBP (γ Prec NBP), NPP (γ Prec NPP), and Rh (γ Prec Rh) are predicted not to change significantly, with large differences among ESMs. Across models, the changes in γ Prec NBP can be mainly explained by changes in γ Prec NPP rather than changes in γ Prec Rh in temperate regions, but not in other regions. Changes in the interannual climate sensitivities of carbon fluxes are consistent across RCPs 4.5, 6.0, and 8.5 but larger in more intensive scenarios. More effort should be considered to improve terrestrial carbon flux responses to interannual climate variability, e.g., incorporating biogeochemical processes of nutrient limitation, permafrost dynamics, and microbial decomposition.

Domaines: Climatologie

Yongwen Liu, Tao Wang, Mengtian Huang, Yitong Yao, Philippe Ciais, et al.. Changes in interannual climate sensitivities of terrestrial carbon fluxes during the 21st century predicted by CMIP5 Earth System Models. Journal of Geophysical Research: Biogeosciences, 2016, 121 (3), pp.903-918. ⟨10.1002/2015JG003124⟩. ⟨hal-02922860⟩