Revised estimates of ocean-atmosphere CO2 flux are consistent with ocean carbon inventory

Watson, Andrew J.; Schuster, Ute; Shutler, Jamie D.; Holding, Thomas; Ashton, Ian; Landschützer, Peter; Woolf, David; Goddijn-Murphy, Lonneke

doi:10.1038/s41467-020-18203-3

Cited by 193 publications

(268 citation statements)

References 43 publications

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“…This global oceanic CO 2 uptake is below previous estimates derived from the observed oceanic pCO 2 (1.4 ± 0.5 GtC/yr as of 2000) (Landschützer et al, 2017) and ocean inverse models (1.7 ± 0.4 GtC/yr as of 1995-2000) (Gruber et al, 2009). The discrepancy would be even larger if we compare our estimates with Watson et al (2020) who suggested an upward revision of a previous estimate of 1.4 ± 0.5 GtC/yr by 0.8-0.9 GtC/yr. Much of this difference can be attributed to the fact that the global integrations were made over different spatial areas.…”

Section: Air-sea Co 2 Exchange In the Open Oceancontrasting

confidence: 71%

Stable Carbon Isotopes Suggest Large Terrestrial Carbon Inputs to the Global Ocean

Kwon

DeVries

Galbraith

et al. 2021

Global Biogeochemical Cycles

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Accurately determining the carbon exchange between the atmosphere, land, and ocean over preindustrial and industrial times is critical for understanding how humans have perturbed the Earth's carbon cycle (Resplandy et al., 2018). The prevailing understanding of the global carbon cycle suggests that in preindustrial times about 0.9 GtC/yr was transferred from land to the ocean (Cole et al., 2007;Meybeck, 1993), of which 0.2 GtC/yr was buried in marine sediments (Sarmiento & Sundquist, 1992) and 0.7 GtC/yr outgassed to the atmosphere (Ciais et al., 2013). Superimposed on these preindustrial carbon fluxes are anthropogenic perturbations consisting of a 0.1 GtC/yr increase in the carbon flux from land to ocean via rivers (Regnier et al., 2013) and the oceanic uptake of anthropogenic CO 2 of 2.3 ± 0.7 GtC/yr as of the 2000s (Sarmiento & Gruber, 2006). Taken together, the inferred net oceanic CO 2 uptake of 1.6 ± 0.7 GtC/yr (consisting of 0.7 GtC/yr outgassing of natural CO 2 and 2.3 ± 0.7 Gt/yr anthropogenic CO 2 uptake) is considered to be in agreement with estimates of the contemporary air-sea CO 2 flux derived from the observed oceanic partial pressure of CO 2 (pCO 2 ) (1.4 ± 0.5 GtC/yr as of 2000) (Landschützer et al., 2017) and ocean inverse models (1.7 ± 0.4 GtC/yr as of 1995-2000) (Gruber et al., 2009). However, this understanding of carbon fluxes

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Section: Air-sea Co 2 Exchange In the Open Oceancontrasting

confidence: 71%

Stable Carbon Isotopes Suggest Large Terrestrial Carbon Inputs to the Global Ocean

Kwon

DeVries

Galbraith

et al. 2021

Global Biogeochemical Cycles

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“…The global CO 2 budget has been assessed by the Intergovernmental Panel on Climate Change (IPCC) in all assessment reports (Prentice et al, 2001;Schimel et al, 1995;Watson et al, 1990;Denman et al, 2007;Ciais et al, 2013), and by others (e.g. Ballantyne et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Global Carbon Budget 2020

Friedlingstein

O’Sullivan

Jones

et al. 2020

Earth Syst. Sci. Data

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1,762

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Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2010–2019), EFOS was 9.6 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.4 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 1.6 ± 0.7 GtC yr−1. For the same decade, GATM was 5.1 ± 0.02 GtC yr−1 (2.4 ± 0.01 ppm yr−1), SOCEAN 2.5 ± 0.6 GtC yr−1, and SLAND 3.4 ± 0.9 GtC yr−1, with a budget imbalance BIM of −0.1 GtC yr−1 indicating a near balance between estimated sources and sinks over the last decade. For the year 2019 alone, the growth in EFOS was only about 0.1 % with fossil emissions increasing to 9.9 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.7 ± 0.5 GtC yr−1 when cement carbonation sink is included), and ELUC was 1.8 ± 0.7 GtC yr−1, for total anthropogenic CO2 emissions of 11.5 ± 0.9 GtC yr−1 (42.2 ± 3.3 GtCO2). Also for 2019, GATM was 5.4 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN was 2.6 ± 0.6 GtC yr−1, and SLAND was 3.1 ± 1.2 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 409.85 ± 0.1 ppm averaged over 2019. Preliminary data for 2020, accounting for the COVID-19-induced changes in emissions, suggest a decrease in EFOS relative to 2019 of about −7 % (median estimate) based on individual estimates from four studies of −6 %, −7 %, −7 % (−3 % to −11 %), and −13 %. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2019, but discrepancies of up to 1 GtC yr−1 persist for the representation of semi-decadal variability in CO2 fluxes. Comparison of estimates from diverse approaches and observations shows (1) no consensus in the mean and trend in land-use change emissions over the last decade, (2) a persistent low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent discrepancy between the different methods for the ocean sink outside the tropics, particularly in the Southern Ocean. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set (Friedlingstein et al., 2019; Le Quéré et al., 2018b, a, 2016, 2015b, a, 2014, 2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2020 (Friedlingstein et al., 2020).

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“…The ocean is the major heat and net carbon uptake reservoir (“sink”) ( 6 , 66 , 67 ). Without ocean uptake, atmospheric warming would already be much larger.…”

Section: Trapped By Oceanic Time Scalesmentioning

confidence: 99%

The quiet crossing of ocean tipping points

Heinze

Blenckner

Martins

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Anthropogenic climate change profoundly alters the ocean’s environmental conditions, which, in turn, impact marine ecosystems. Some of these changes are happening fast and may be difficult to reverse. The identification and monitoring of such changes, which also includes tipping points, is an ongoing and emerging research effort. Prevention of negative impacts requires mitigation efforts based on feasible research-based pathways. Climate-induced tipping points are traditionally associated with singular catastrophic events (relative to natural variations) of dramatic negative impact. High-probability high-impact ocean tipping points due to warming, ocean acidification, and deoxygenation may be more fragmented both regionally and in time but add up to global dimensions. These tipping points in combination with gradual changes need to be addressed as seriously as singular catastrophic events in order to prevent the cumulative and often compounding negative societal and Earth system impacts.

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Revised estimates of ocean-atmosphere CO2 flux are consistent with ocean carbon inventory

Cited by 193 publications

References 43 publications

Stable Carbon Isotopes Suggest Large Terrestrial Carbon Inputs to the Global Ocean

Stable Carbon Isotopes Suggest Large Terrestrial Carbon Inputs to the Global Ocean

Global Carbon Budget 2020

The quiet crossing of ocean tipping points

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