Validation of Terrestrial Biogeochemistry in CMIP6 Earth System Models: A Review

Spafford, Lynsay; MacDougall, Andrew H.

doi:10.5194/gmd-2021-150

Cited by 5 publications

(5 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Knowledge of what observational constraints have been used to constrain ocean biogeochemical models would critically improve our understanding of the uncertainty in NPP projections. In this respect, much could be learned from the terrestrial biogeochemistry community (e.g., Spafford and MacDougall, 2021).…”

Section: Future Efforts To Reduce Uncertainty In Npp Projectionsmentioning

confidence: 99%

Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services

et al. 2021

View full text Add to dashboard Cite

Ocean net primary production (NPP) results from CO2 fixation by marine phytoplankton, catalysing the transfer of organic matter and energy to marine ecosystems, supporting most marine food webs, and fisheries production as well as stimulating ocean carbon sequestration. Thus, alterations to ocean NPP in response to climate change, as quantified by Earth system model experiments conducted as part of the 5th and 6th Coupled Model Intercomparison Project (CMIP5 and CMIP6) efforts, are expected to alter key ecosystem services. Despite reductions in inter-model variability since CMIP5, the ocean components of CMIP6 models disagree roughly 2-fold in the magnitude and spatial distribution of NPP in the contemporary era, due to incomplete understanding and insufficient observational constraints. Projections of NPP change in absolute terms show large uncertainty in CMIP6, most notably in the North Atlantic and the Indo-Pacific regions, with the latter explaining over two-thirds of the total inter-model uncertainty. While the Indo-Pacific has previously been identified as a hotspot for climate impacts on biodiversity and fisheries, the increased inter-model variability of NPP projections further exacerbates the uncertainties of climate risks on ocean-dependent human communities. Drivers of uncertainty in NPP changes at regional scales integrate different physical and biogeochemical factors that require more targeted mechanistic assessment in future studies. Globally, inter-model uncertainty in the projected changes in NPP has increased since CMIP5, which amplifies the challenges associated with the management of associated ecosystem services. Notably, this increased regional uncertainty in the projected NPP change in CMIP6 has occurred despite reduced uncertainty in the regional rates of NPP for historical period. Improved constraints on the magnitude of ocean NPP and the mechanistic drivers of its spatial variability would improve confidence in future changes. It is unlikely that the CMIP6 model ensemble samples the complete uncertainty in NPP, with the inclusion of additional mechanistic realism likely to widen projections further in the future, especially at regional scales. This has important consequences for assessing ecosystem impacts. Ultimately, we need an integrated mechanistic framework that considers how NPP and marine ecosystems respond to impacts of not only climate change, but also the additional non-climate drivers.

show abstract

Section: Future Efforts To Reduce Uncertainty In Npp Projectionsmentioning

confidence: 99%

Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services

et al. 2021

View full text Add to dashboard Cite

show abstract

“…2). Comprehensive and standard validations of multiple variables are needed to assess the model performance and uncertainties in biogeochemical simulations across CMIP6 models (Spafford and MacDougall, 2021).…”

Section: Discussionmentioning

confidence: 99%

Global and northern-high-latitude net ecosystem production in the 21st century from CMIP6 experiments

Qiu

Hao²,

Zeng³

et al. 2023

Earth Syst. Dynam.

View full text Add to dashboard Cite

Abstract. Climate warming is accelerating the changes in the global terrestrial ecosystems and particularly those in the northern high latitudes (NHLs; poleward of 50∘ N) 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 10 CMIP6 models, we quantitatively evaluated the projected magnitudes, trends, and uncertainties in the global and NHL carbon fluxes under four scenarios plus the role of NHLs 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 magnitude of the carbon sinks is projected to be larger under scenarios with higher radiative forcing. By the end of this century, the models on 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 Pg C yr−1 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 NHLs contribute a small fraction of the global carbon sink (∼ 13 %), the relative uncertainties in 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.

show abstract

“…Considering the enormous uncertainty that still exists in the magnitude of carbon‐climate feedbacks in Earth system models (Spafford & MacDougall, 2021) we argue that the availability of fundamentally different model approaches capable of predicting near‐similar responses in leaf‐level photosynthesis can facilitate testing and model development via intercomparison. Differences between FvCB and G85‐based photosynthesis schemes in future model intercomparison should be acknowledged while photosynthesis parameters between vegetation types can be aligned to minimize model variance due to inconsistent model input parameters.…”

Section: Discussionmentioning

confidence: 99%

Comparison of C3 Photosynthetic Responses to Light and CO₂ Predicted by the Leaf Photosynthesis Models of Farquhar et al. (1980) and Goudriaan et al. (1985)

Diepen

Goudriaan

Arellano

et al. 2022

J Adv Model Earth Syst

View full text Add to dashboard Cite

The leaf photosynthesis models developed by Farquhar et al. (1980, https://doi.org/10.1007/BF00386231) (FvCB) and Goudriaan et al. (1985, https://doi.org/10.1007/978-1-4899-3665-3_10) (G85) are both used in Earth system and weather models to quantify ecosystem carbon assimilation. Despite their common role, a systematic comparison between these two photosynthesis models is currently lacking in scientific literature. In this technical report we compared the two models in a systematic way. Hereto we performed a comparative analysis of the model structures as well as the modeled responses of photosynthesis to light and CO2 at leaf level. To facilitate future model comparison, we also constructed a lookup table that presents FvCB model parameters fitted to CO2‐response curves from G85 in a wide natural range in photosynthetic capacity at standardized temperature. The structure of the FvCB model differs fundamentally from the G85 model as the FvCB model considers rate‐limiting processes due to Rubisco capacity, electron transport and triose phosphate utilization in parallel, whereas the G85 model considers Rubisco activity and triose phosphate utilization limitation to act in series scaled with quantum use efficiency. The models also differ fundamentally in terms of the parametrization of dark respiration. Still, both models calculate near‐similar responses of photosynthesis to changes in light and CO2 across a wide range in photosynthetic capacity with only two free parameters each. Our work thereby highlights functional similarities between these model approaches despite fundamental differences in model structure. Hence, standardized parameter sets that yield similar photosynthesis responses to light and CO2 may facilitate intercomparison of Earth system and weather models.

show abstract

Validation of Terrestrial Biogeochemistry in CMIP6 Earth System Models: A Review

Cited by 5 publications

References 61 publications

Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services

Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services

Global and northern-high-latitude net ecosystem production in the 21st century from CMIP6 experiments

Comparison of C3 Photosynthetic Responses to Light and CO₂ Predicted by the Leaf Photosynthesis Models of Farquhar et al. (1980) and Goudriaan et al. (1985)

Contact Info

Product

Resources

About

Validation of Terrestrial Biogeochemistry in CMIP6 Earth System Models: A Review

Cited by 5 publications

References 61 publications

Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services

Persistent Uncertainties in Ocean Net Primary Production Climate Change Projections at Regional Scales Raise Challenges for Assessing Impacts on Ecosystem Services

Global and northern-high-latitude net ecosystem production in the 21st century from CMIP6 experiments

Comparison of C3 Photosynthetic Responses to Light and CO2 Predicted by the Leaf Photosynthesis Models of Farquhar et al. (1980) and Goudriaan et al. (1985)

Contact Info

Product

Resources

About

Comparison of C3 Photosynthetic Responses to Light and CO₂ Predicted by the Leaf Photosynthesis Models of Farquhar et al. (1980) and Goudriaan et al. (1985)