Alternate Histories: Synthetic Large Ensembles of Sea‐Air CO 2 Flux
| Type | Article | ||||||||||||
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| Date | 2022-06 | ||||||||||||
| Language | English | ||||||||||||
| Author(s) | Olivarez Holly C. 1, 2, Lovenduski Nicole S.2, 3, Brady Riley X.2, 3, Fay Amanda R.4, Gehlen Marion5, Gregor Luke6, Landschützer Peter7, McKinley Galen A.4, McKinnon Karen A.8, Munro David R.9 |
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| Affiliation(s) | 1 : Department of Environmental Studies University of Colorado Boulder CO, USA 2 : Institute of Arctic and Alpine Research University of Colorado Boulder CO, USA 3 : Department of Atmospheric and Oceanic Sciences University of Colorado Boulder CO, USA 4 : Columbia University and Lamont‐Doherty Earth Observatory Palisades NY ,USA 5 : Institut Pierre‐Simon Laplace Laboratoire des Sciences du Climat et de l’Environnement Gif‐sur‐Yvette ,France 6 : Environmental Physics Institute of Biogeochemistry and Pollutant Dynamics ETH Zürich Zürich ,Switzerland 7 : Max Planck Institute for Meteorology Hamburg ,Germany 8 : Department of Statistics and Institute of the Environment and Sustainability University of California Los Angeles CA, USA 9 : National Oceanic and Atmospheric Administration Global Monitoring Laboratory and Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder CO ,USA |
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| Source | Global Biogeochemical Cycles (0886-6236) (American Geophysical Union (AGU)), 2022-06 , Vol. 36 , N. 6 , P. e2021GB007174 (16p.) | ||||||||||||
| DOI | 10.1029/2021GB007174 | ||||||||||||
| WOS© Times Cited | 3 | ||||||||||||
| Note | This article also appears in: Understanding Carbon-Climate Feedbacks | ||||||||||||
| Keyword(s) | global carbon cycle, air-sea CO2 flux, ocean carbon uptake, large ensemble, Earth system modeling, decadal trends | ||||||||||||
| Abstract | We use a statistical emulation technique to construct synthetic ensembles of global and regional sea-air carbon dioxide (CO2) flux from four observation-based products over 1985–2014. Much like ensembles of Earth system models that are constructed by perturbing their initial conditions, our synthetic ensemble members exhibit different phasing of internal variability and a common externally forced signal. Our synthetic ensembles illustrate an important role for internal variability in the temporal evolution of global and regional CO2 flux and produce a wide range of possible trends over 1990–1999 and 2000–2009. We assume a specific externally forced signal and calculate the rank of the observed trends within the distribution of statistically modeled synthetic trends during these periods. Over the decade 1990–1999, three of four observation-based products exhibit small negative trends in globally integrated sea-air CO2 flux (i.e., enhanced ocean CO2 absorption with time) that are within one standard deviation of the mean in their respective synthetic ensembles. Over the decade 2000–2009, however, three products show large negative trends in globally integrated sea-air CO2 flux that have a low rate of occurrence in their synthetic ensembles. The largest positive trends in global and Southern Ocean flux over 1990–1999 and the largest negative trends over 2000–2009 fall nearly two standard deviations away from the mean in their ensembles. Our approach provides a new perspective on the important role of internal variability in sea-air CO2 flux trends, and furthers understanding of the role of internal and external processes in driving observed sea-air CO2 flux variability. Key Points We construct synthetic large ensembles of observed sea-air carbon dioxide flux using a statistical emulation technique The synthetic large ensembles illustrate an important role for internal variability in the temporal evolution of carbon dioxide flux We find a wide range of possible decadal trends in carbon dioxide flux over 1990–1999 and 2000–2009 driven by internal variability |
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