Examining the sensitivity of the terrestrial carbon cycle to the expression of El Niño

Teckentrup, Lina; Kauwe, Martin G. De; Pitman, Andrew J.; Smith, Benjamin

doi:10.5194/bg-18-2181-2021

Cited by 4 publications

(6 citation statements)

References 71 publications

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“…Our scientific findings regarding the trends in the airborne fraction of CO 2 (AF) are unaffected if we use the N3.4 index rather than the N4 and N1+2 indices. The inclusion of two indices representing the cumulative effect of ENSO on the CO 2 growth rate in our baseline MLR simulation is motivated by recent studies that report differing responses in various components of the carbon cycle to El Niño events originating in the Central or Eastern Pacific (Chylek et al., 2018; Pan et al., 2018; Teckentrup et al., 2021; Wang et al., 2018).…”

Section: Resultsmentioning

confidence: 99%

“…Several recent studies have examined the sensitivity of the carbon cycle to the type of ENSO, quantifying and comparing the effects of a Central Pacific (CP) and an Eastern Pacific (EP) ENSO index (Chylek et al., 2018; Teckentrup et al., 2021; Wang et al., 2018). In our MLR modeling analysis, we consider the use of both a CP and an EP ENSO index, N4 and N1+2, respectively, and a single ENSO index, Niño 3.4, as predictors for d CO 2 GLB−RAW / dt .…”

Section: Methodsmentioning

confidence: 99%

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Quantification of the Airborne Fraction of Atmospheric CO₂ Reveals Stability in Global Carbon Sinks Over the Past Six Decades

Bennett,

Salawitch,

McBride

et al. 2024

JGR Biogeosciences

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The airborne fraction of atmospheric CO2 (AF), defined as the annual global CO2 growth rate (dCO2/dt) divided by the total emission of CO2 from combustion of fossil fuels and land use change (LUC), has a long‐term average of ∼0.44 over the past six decades. When quantifying trends in AF it is important to account for inter‐annual variability in dCO2/dt due to natural factors such as the El Niño Southern Oscillation (ENSO) and major volcanic eruptions, as well as assumptions regarding LUC. Here, a multiple linear regression model is used to compute dCO2/dt as a function of anthropogenic CO2 emissions, ENSO indices, and stratospheric aerosol optical depth (a proxy for major volcanic eruptions), for numerous time series of the emission of CO2 due to LUC (ELUC). For 20 out of 21 previously published ELUC time series, the trend in AF adjusted for natural variability (AFADJ) over 1959 to 2021 exhibits a trend that is statistically indistinguishable from zero and lacks statistical significance at the 95% confidence interval. Therefore, it is most likely that the relative efficacy of the combined global terrestrial biosphere and oceanic carbon sinks has been fairly constant on a global scale over the past six decades. Since the trend in AF exhibits considerable variability depending on which ELUC time series is used, more precise knowledge of the actual value of the AF trend will require resolving the current large differences in various estimates of ELUC.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Quantification of the Airborne Fraction of Atmospheric CO₂ Reveals Stability in Global Carbon Sinks Over the Past Six Decades

Bennett,

Salawitch,

McBride

et al. 2024

JGR Biogeosciences

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“…Zhang et al, 2019;Wells et al, 2020) or with transient (i.e historical) simulations (e.g. Bastos et al, 2018;Teckentrup et al, 2021). The advantage of the isolated ENSO simulations implemented in the constant climate boundary conditions (i.e.…”

Section: Isolated Enso Event Simulationsmentioning

confidence: 99%

“…Several studies explored the sensitivity of the terrestrial biosphere to different ENSO phases (e.g., Ahlström et al, 2015;Chang et al, 2017;Bastos et al, 2018;Teckentrup et al, 2021). The primary factors driving changes in vegetation are closely linked to the dominant meteorological drivers of net primary productivity (NPP) in different regions.…”

Section: Introductionmentioning

confidence: 99%

BVOC emission flux response to the El Niño-Southern Oscillation

Vella

Pozzer

Forrest

et al. 2023

Preprint

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Abstract. Isoprene and monoterpene emissions from the terrestrial biosphere play a significant role in major atmospheric processes. Emissions depend on the vegetation's response to atmospheric conditions (primarily temperature and light), as well as other stresses e.g. from droughts and herbivory. It has been well documented that biogenic volatile organic compound (BVOC) emissions are sensitive to climatic influences. The El Niño-Southern Oscillation (ENSO) is a natural cycle, arising from sea surface temperature (SST) anomalies in the tropical Pacific, which perturbs the natural seasonality of weather systems on both global and regional scales. Several studies evaluated the sensitivity of BVOC fluxes during ENSO events using historical transient simulations. While this approach employs realistic scenarios, it is difficult to assess the individual impact of ENSO given multiple forcing on the climate system e.g. from anthropogenic emissions of CO2 and aerosol. In this study, a global atmospheric chemistry-climate model with enabled interactive vegetation was used to conduct two sets of simulations: 1) isolated ENSO event simulations, in which a single ENSO event is used to perturb otherwise baseline conditions, and 2) sustained ENSO simulations, in which the same ENSO conditions are reproduced for an extended period of time. From the isolated ENSO events, we present global and regional BVOC emission changes resulting from the immediate vegetation response to atmospheric states. More focus is given to the sustained ENSO simulations which have the benefit of reducing the internal variability for more robust statistics when linking atmospheric and vegetation variables with BVOC flux anomalies. Additionally, these simulations explore long-term changes in the biosphere with potential shifts in vegetation in this possible climate mode, accounting for the prospect of increased intensity and frequency of ENSO with climate change. Our results show that strong El Niño events increase global isoprene emission fluxes by 2.9 % and that one single ENSO event perturbs the Earth system to the point where BVOC emission fluxes do not return to baseline emissions within several years after the event. We show that persistent ENSO conditions shift the vegetation to a new quasi-equilibrium state, leading to an amplification of BVOC emission changes with up to 19 % increase in isoprene fluxes over the Amazon. We provide evidence that BVOC-induced changes in plant phenology such as the leaf area index (LAI), have a significant influence on BVOC emissions in the sustained ENSO climate mode.

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“…Several studies have explored the sensitivity of the terrestrial biosphere to different ENSO phases (e.g. Ahlström et al, 2015;Chang et al, 2017;Bastos et al, 2018;Wang et al, 2018;Teckentrup et al, 2021). The primary factors driving changes in vegetation are closely linked to the dominant meteorological drivers of net primary productivity (NPP) in different regions.…”

Section: Introductionmentioning

confidence: 99%

Changes in biogenic volatile organic compound emissions in response to the El Niño–Southern Oscillation

Vella,

Pozzer,

Forrest

et al. 2023

Biogeosciences

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Abstract. Emissions of biogenic volatile organic compounds (BVOCs) from the terrestrial biosphere play a significant role in major atmospheric processes. BVOCs are highly reactive compounds that influence the atmosphere's oxidation capacity and also serve as precursors for the formation of aerosols that influence global radiation budgets. Emissions depend on the response of vegetation to atmospheric conditions (primarily temperature and light), as well as other stresses, e.g. from droughts and herbivory. The El Niño–Southern Oscillation (ENSO) is a naturally occurring cycle arising from anomalies in the sea surface temperature (SST) in the tropical Pacific. ENSO perturbs the natural seasonality of weather systems on both global and regional scales and is considered the most significant driver of climate variability. Several studies have evaluated the sensitivity of BVOC fluxes during ENSO events using historical transient simulations. While this approach employs realistic scenarios, it is difficult to assess the impact of ENSO alone given the multiple types of climate forcing, e.g. from anthropogenic emissions of CO2 and aerosol. In this study, a global atmospheric chemistry–climate model with enabled interactive vegetation was used to conduct two sets of simulations: (1) isolated ENSO event simulations, in which a single ENSO event is used to perturb otherwise baseline conditions, and (2) sustained ENSO simulations, in which the same ENSO conditions are reproduced for an extended period of time. From the isolated ENSO events, we present global and regional BVOC emission changes resulting from the immediate response of vegetation to atmospheric states. More focus is given to the sustained ENSO simulations, which have the benefit of reducing the internal variability for more robust statistics when linking atmospheric and vegetation variables with BVOC flux anomalies. Additionally, these simulations explore long-term changes in the biosphere with potential shifts in vegetation in this possible climate mode, accounting for the prospect of increased intensity and frequency of ENSO with climate change. Our results show that strong El Niño events increase global isoprene emission fluxes by 2.9 % and that one single ENSO event perturbs the Earth system so markedly that BVOC emission fluxes do not return to baseline emissions within several years after the event. We show that persistent ENSO conditions shift the vegetation to a new quasi-equilibrium state, leading to an amplification of BVOC emission changes with up to a 19 % increase in isoprene fluxes over the Amazon. We provide evidence that BVOC-induced changes in plant phenology, such as the leaf area index (LAI), have a significant influence on BVOC emissions in the sustained ENSO climate mode.

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Examining the sensitivity of the terrestrial carbon cycle to the expression of El Niño

Cited by 4 publications

References 71 publications

Quantification of the Airborne Fraction of Atmospheric CO₂ Reveals Stability in Global Carbon Sinks Over the Past Six Decades

Quantification of the Airborne Fraction of Atmospheric CO₂ Reveals Stability in Global Carbon Sinks Over the Past Six Decades

BVOC emission flux response to the El Niño-Southern Oscillation

Changes in biogenic volatile organic compound emissions in response to the El Niño–Southern Oscillation

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Examining the sensitivity of the terrestrial carbon cycle to the expression of El Niño

Cited by 4 publications

References 71 publications

Quantification of the Airborne Fraction of Atmospheric CO2 Reveals Stability in Global Carbon Sinks Over the Past Six Decades

Quantification of the Airborne Fraction of Atmospheric CO2 Reveals Stability in Global Carbon Sinks Over the Past Six Decades

BVOC emission flux response to the El Niño-Southern Oscillation

Changes in biogenic volatile organic compound emissions in response to the El Niño–Southern Oscillation

Contact Info

Product

Resources

About

Quantification of the Airborne Fraction of Atmospheric CO₂ Reveals Stability in Global Carbon Sinks Over the Past Six Decades

Quantification of the Airborne Fraction of Atmospheric CO₂ Reveals Stability in Global Carbon Sinks Over the Past Six Decades