Trends and regional distributions of land and ocean carbon sinks

Sarmiento, Jorge L.; Gloor, M.; Gruber, Nicolas; Beaulieu, Claudie; Jacobson, A. R.; Fletcher, S. E. Mikaloff; Pacala, Stephen W.; Rodgers, Keith B.

doi:10.5194/bg-7-2351-2010

Cited by 189 publications

(216 citation statements)

References 73 publications

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“…North America there are some regions with an increase in uptake as well as some with a decrease. The growth rate of atmospheric CO 2 slowed after the Pinatubo eruption, which is consistent with a net uptake of CO 2 by the land and oceans in the years after the eruption (Sarmiento et al, 2010), as seen in these simulations, although the signal was not statistically significant (Fig. 2b).…”

Section: Biogeochemical Responses To the Pinatubo Eruptionsupporting

confidence: 62%

“…Some authors argue that the additional nutrients and trace elements added to the ocean may be responsible for additional carbon uptake (e.g., Watson, 1997;Frogner et al, 2001;Duggen et al, 2007Duggen et al, , 2010, but a quantitative assessment of this effect on global carbon or ocean productivity has not yet been performed. The strength at which land and ocean sinks reduce atmospheric CO 2 is not increasing at the same rate as anthropogenic emissions are increasing (Le Quéré et al, 2009;Sarmiento et al, 2010), as evidenced by an increase in atmospheric CO 2 levels. Modeling studies suggest that the balance of increased carbon uptake associated with CO 2 fertilization and decreased uptake associated with global warming could lead to a reduction in the efficiency of the land sink of carbon in the future (Cox et al, 2000;Friedlingstein et al, 2006;Thornton et al, 2009;Sitch et al, 2008).…”

Section: Introductionmentioning

confidence: 94%

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Volcano impacts on climate and biogeochemistry in a coupled carbon–climate model

et al. 2012

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Abstract. Volcanic eruptions induce a dynamical response in the climate system characterized by short-term global reductions in both surface temperature and precipitation, as well as a response in biogeochemistry. The available observations of these responses to volcanic eruptions, such as to Pinatubo, provide a valuable method to compare against model simulations. Here, the Community Climate System Model Version 3 (CCSM3) reproduces the physical climate response to volcanic eruptions in a realistic way, as compared to direct observations from the 1991 eruption of Mount Pinatubo. The model's biogeochemical response to eruptions is smaller in magnitude than observed, but because of the lack of observations, it is not clear why or where the modeled carbon response is not strong enough. Comparison to other models suggests that this model response is much weaker over tropical land; however, the precipitation response in other models is not accurate, suggesting that other models could be getting the right response for the wrong reason. The underestimated carbon response in the model compared to observations could also be due to the ash and lava input of biogeochemically important species to the ocean, which are not included in the simulation. A statistically significant reduction in the simulated carbon dioxide growth rate is seen at the 90 % level in the average of 12 large eruptions over the period 1870-2000, and the net uptake of carbon is primarily concentrated in the tropics, with large spatial variability. In addition, a method for computing the volcanic response in model output without using a control ensemble is tested against a traditional methodology using two separate ensembles of runs; the method is found to produce similar results in the global average. These results suggest that not only is simulating volcanoes a good test of coupled carbon-climate models, but also that this test can be performed without a control simulation in cases where it is not practical to run separate ensembles with and without volcanic eruptions.

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Section: Biogeochemical Responses To the Pinatubo Eruptionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 94%

Volcano impacts on climate and biogeochemistry in a coupled carbon–climate model

et al. 2012

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“…First, recent papers (Canadell et al, 2007;Raupach et al, 2008;Le Quéré et al, 2009) have suggested that there is a detectable increasing trend in the AF from 1959 to the early 2000s, at a relative growth rate of 0.2 to 0.3 % yr −1 . This finding has been contested on several grounds, mainly questioning the attribution of the observed trend in the AF rather than its existence: the observed trend has been attributed to slower-than-exponential growth in f E , to particular events such as volcanic eruptions and ENSO (El Niño-Southern Oscillation) events Sarmiento et al, 2010), or to errors in CO 2 emissions data in Observed CO 2 airborne fraction (AF, Eq. 11) and cumulative airborne fraction (CAF, Eq.…”

Section: Ratios Among Fluxes and State Variablesmentioning

confidence: 99%

The exponential eigenmodes of the carbon-climate system, and their implications for ratios of responses to forcings

Raupach

2013

Earth Syst. Dynam.

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Abstract. Several basic ratios of responses to forcings in the carbon-climate system are observed to be relatively steady. Examples include the CO 2 airborne fraction (the fraction of the total anthropogenic CO 2 emission flux that accumulates in the atmosphere) and the ratio T /Q E of warming (T ) to cumulative total CO 2 emissions (Q E ). This paper explores the reason for such near-constancy in the past, and its likely limitations in future.The contemporary carbon-climate system is often approximated as a set of first-order linear systems, for example in response-function descriptions. All such linear systems have exponential eigenfunctions in time (an eigenfunction being one that, if applied to the system as a forcing, produces a response of the same shape). This implies that, if the carbonclimate system is idealised as a linear system (Lin) forced by exponentially growing CO 2 emissions (Exp), then all ratios of responses to forcings are constant. Important cases are the CO 2 airborne fraction (AF), the cumulative airborne fraction (CAF), other CO 2 partition fractions and cumulative partition fractions into land and ocean stores, the CO 2 sink uptake rate (k S , the combined land and ocean CO 2 sink flux per unit excess atmospheric CO 2 ), and the ratio T /Q E . Further, the AF and the CAF are equal. Since the Lin and Exp idealisations apply approximately to the carbon-climate system over the past two centuries, the theory explains the observed near-constancy of the AF, CAF and T /Q E in this period.A nonlinear carbon-climate model is used to explore how future breakdown of both the Lin and Exp idealisations will cause the AF, CAF and k S to depart significantly from constancy, in ways that depend on CO 2 emissions scenarios. However, T /Q E remains approximately constant in typical scenarios, because of compensating interactions between CO 2 emissions trajectories, carbon-climate nonlinearities (in land-air and ocean-air carbon exchanges and CO 2 radiative forcing), and emissions trajectories for non-CO 2 gases. This theory establishes a basis for the widely assumed proportionality between T and Q E , and identifies the limits of this relationship.

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“…3a) the 'land residual sink' is deduced as a difference between fossil-fuel and land-use-change emissions of C and atmospheric accumulation and open-ocean uptake 21,22,95 , the ocean component being estimated from forward and inverse models 21,96 . This method implicitly assumes that the pre-anthropogenic global carbon budget was at steady state and the fluxes along the land-ocean aquatic continuum, unlike most other fluxes, have no anthropogenic component.…”

Section: Implications For the Global Carbon Budgetmentioning

confidence: 99%

Anthropogenic perturbation of the carbon fluxes from land to ocean

et al. 2013

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A substantial amount of the atmospheric carbon taken up on land through photosynthesis and chemical weathering is transported laterally along the aquatic continuum from upland terrestrial ecosystems to the ocean. So far, global carbon budget estimates have implicitly assumed that the transformation and lateral transport of carbon along this aquatic continuum has remained unchanged since pre-industrial times. A synthesis of published work reveals the magnitude of present-day lateral carbon fluxes from land to ocean, and the extent to which human activities have altered these fluxes. We show that anthropogenic perturbation may have increased the flux of carbon to inland waters by as much as 1.0 Pg C yr(-1) since pre-industrial times, mainly owing to enhanced carbon export from soils. Most of this additional carbon input to upstream rivers is either emitted back to the atmosphere as carbon dioxide (similar to 0.4 Pg C yr(-1)) or sequestered in sediments (similar to 0.5 Pg C yr(-1)) along the continuum of freshwater bodies, estuaries and coastal waters, leaving only a perturbation carbon input of similar to 0.1 Pg C yr(-1) to the open ocean. According to our analysis, terrestrial ecosystems store similar to 0.9 Pg C yr(-1) at present, which is in agreement with results from forest inventories but significantly differs from the figure of 1.5 Pg C yr(-1) previously estimated when ignoring changes in lateral carbon fluxes. We suggest that carbon fluxes along the land-ocean aquatic continuum need to be included in global carbon dioxide budgets

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Trends and regional distributions of land and ocean carbon sinks

Cited by 189 publications

References 73 publications

Volcano impacts on climate and biogeochemistry in a coupled carbon–climate model

Volcano impacts on climate and biogeochemistry in a coupled carbon–climate model

The exponential eigenmodes of the carbon-climate system, and their implications for ratios of responses to forcings

Anthropogenic perturbation of the carbon fluxes from land to ocean

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