Compensatory Effects between CO2, Nitrogen Deposition, and Temperature in Terrestrial Biosphere Models without Nitrogen Compromise Projections of the Future Terrestrial Carbon Sink

Kou‐Giesbrecht, Sian; Arora, Vivek K.

doi:10.22541/essoar.167169640.09413994/v1

Cited by 3 publications

(4 citation statements)

References 46 publications

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“…During the 2080-2099 period, on the other hand, the nitrogen cycle weakens the increase of NBP, such that NBP is 54% less compared to projections when the nitrogen cycle is turned off. The impact of the nitrogen cycle during the future period is consistent with how nutrient availability limits the CO 2 fertilization effect, confirming findings from previous studies (Zaehle et al, 2010;Huntzinger et al, 2017;Meyerholt et al, 2020;Kou-Giesbrecht & Arora, 2022a).…”

Section: Discussionsupporting

confidence: 88%

The Impact of Climate Forcing Biases and the Nitrogen Cycle on Land Carbon Balance Projections

Seiler

Kou‐Giesbrecht

Arora

et al. 2023

Preprint

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Earth System Models (ESMs) project that the terrestrial carbon sink will continue to grow as atmospheric CO$_2$ increases, but this projection is uncertain due to biases in the simulated climate and how ESMs represent ecosystem processes. In particular, the strength of the CO$_2$ fertilization effect, which is modulated by nutrient cycles, varies substantially across models. This study evaluates land carbon balance uncertainties for the Canadian Earth System Model (CanESM) by conducting simulations where the latest version of CanESM’s land surface component is driven offline with raw and bias-adjusted CanESM5 climate forcing data. To quantify the impact of nutrient limitation, we complete simulations where the nitrogen cycle is enabled or disabled. Results show that bias adjustment improves model performance across most ecosystem variables, primarily due to reduced biases in precipitation. Turning the nitrogen cycle on increases the global land carbon sink during the historical period (1995-2014) due to enhanced nitrogen deposition, placing it within the Global Carbon Budget uncertainty range. During the future period (2080-2099), the simulated land carbon sink increases in response to bias adjustment and decreases in response to the dynamic carbon-nitrogen interaction, leading to a net decrease when both factors are acting together. The dominating impact of the nitrogen cycle demonstrates the importance of representing nutrient limitation in ESMs. Such efforts may produce more robust carbon balance projections in support of global climate change mitigation policies such as the 2015 Paris Agreement.

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Section: Discussionsupporting

confidence: 88%

The Impact of Climate Forcing Biases and the Nitrogen Cycle on Land Carbon Balance Projections

Seiler

Kou‐Giesbrecht

Arora

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…During the 2080–2099 period, on the other hand, the nitrogen cycle weakens the increase of NBP, such that NBP is 54% less compared to projections when the nitrogen cycle is turned off. The impact of the nitrogen cycle during the future period is consistent with how nutrient availability limits the CO 2 ‐fertilization effect, confirming findings from previous studies (Huntzinger et al., 2017; Kou‐Giesbrecht & Arora, 2022a; Meyerholt et al., 2020; Zaehle et al., 2010). The prescribed supply of nitrogen through deposition and fertilization, therefore, presents another potentially important source of uncertainty for simulating the land carbon balance.…”

Section: Discussionsupporting

confidence: 88%

The Impact of Climate Forcing Biases and the Nitrogen Cycle on Land Carbon Balance Projections

Seiler,

Kou‐Giesbrecht,

Arora

et al. 2024

J Adv Model Earth Syst

Self Cite

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Earth System Models (ESMs) project that the terrestrial carbon sink will continue to grow as atmospheric CO2 increases, but this projection is uncertain due to biases in the simulated climate and how ESMs represent ecosystem processes. In particular, the strength of the CO2‐fertilization effect, which is modulated by nutrient cycles, varies substantially across models. This study evaluates land carbon balance uncertainties for the Canadian Earth System Model (CanESM) by conducting simulations where the latest version of CanESM's land surface component is driven offline with raw and bias‐adjusted CanESM5 climate forcing data. To quantify the impact of nutrient limitation, we complete simulations where the nitrogen cycle is enabled or disabled. Results show that bias adjustment improves model performance across most ecosystem variables, primarily due to reduced biases in precipitation. Turning the nitrogen cycle on increases the global land carbon sink during the historical period (1995–2014) due to enhanced nitrogen deposition, placing it within the Global Carbon Budget uncertainty range. During the future period (2080–2099), the simulated land carbon sink increases in response to bias adjustment and decreases in response to the dynamic carbon‐nitrogen interaction, leading to a net decrease when both factors are acting together. The dominating impact of the nitrogen cycle demonstrates the importance of representing nutrient limitation in ESMs. Such efforts may produce more robust carbon balance projections in support of global climate change mitigation policies such as the 2015 Paris Agreement.

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“…These additional processes could include consideration of fire severity (e.g. smoldering versus crown fire), depth of fire burn, vegetation fuel quality, disturbance-mediated subgrid-scale heterogeneity, shifts in vegetation cover, nutrient cycling, peatland hydrology, peatland soils, overwintering fire, landscape fragmentation, and fire suppression policy 4,12,20,48,[67][68][69][70][71][72][73][74][75][76] . Nevertheless, by representing the influence of fuel moisture content, atmospheric humidity, and ignition on wildfire our FWI-based module realistically represents wildfire in Canada.…”

Section: Climate and Lightning Determine Future Fire Trajectoriesmentioning

confidence: 99%

“…The fifty-four factorial simulations are intended to disentangle the contributions of CO 2 fertilization effects on vegetation, climate trends, anthropogenic ignition/suppression (population density) trends, and lightning ignition trends to future changes in burned area and fire CO 2 emissions. We did this by conducting model and SSP-specific future simulations with different combinations of these forcings fixed at their 2014 levels to isolate their impact on the simulated trends following the methods of Kou-Giesbrecht and Arora 74 . These simulations are detailed in Table S1.…”

Section: Simulation Protocolmentioning

confidence: 99%

Canada's wildfire future: climate change below a 2°C global target avoids large increases in burned area by the end of the century

Curasi,

Melton,

Arora

et al. 2024

Preprint

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Wildfire impacts the global carbon cycle, as well as property, harvestable timber, and public health. Canada saw a record fire season in 2023 with 14.9 Mha burned—over seven times the 1986 - 2022 average of 2.1 Mha. Here we utilize a new process-based wildfire module that explicitly represents fire weather, fuel type and availability, ignition sources, fire suppression, and vegetation’s climate response to project the future of wildfire in Canada. Under rapid climate change (shared socioeconomic pathway [SSP] 370 & 585) simulated annual burned area in the 2090s reaches 10.5 ± 2.1 to 11.7 ± 2.4 Mha, approaching the 2023 fire season total. However, climate change below a 2°C global target (SSP 126), keeps the 2090s area burned near modern (2004 - 2014) norms. Simulated area burned and carbon emissions are most sensitive to climate drivers and lightning but future lightning activity is a key uncertainty.

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Compensatory Effects between CO2, Nitrogen Deposition, and Temperature in Terrestrial Biosphere Models without Nitrogen Compromise Projections of the Future Terrestrial Carbon Sink

Cited by 3 publications

References 46 publications

The Impact of Climate Forcing Biases and the Nitrogen Cycle on Land Carbon Balance Projections

The Impact of Climate Forcing Biases and the Nitrogen Cycle on Land Carbon Balance Projections

The Impact of Climate Forcing Biases and the Nitrogen Cycle on Land Carbon Balance Projections

Canada's wildfire future: climate change below a 2°C global target avoids large increases in burned area by the end of the century

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