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Wendt KA, Nehrbass-Ahles C, Niezgoda K, Noone D, Kalk M, Menviel L, Gottschalk J, Rae JWB, Schmitt J, Fischer H, Stocker TF, Muglia J, Ferreira D, Marcott SA, Brook E, Buizert C. Southern Ocean drives multidecadal atmospheric CO 2 rise during Heinrich Stadials. Proc Natl Acad Sci U S A 2024; 121:e2319652121. [PMID: 38739805 DOI: 10.1073/pnas.2319652121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/28/2024] [Indexed: 05/16/2024] Open
Abstract
The last glacial period was punctuated by cold intervals in the North Atlantic region that culminated in extensive iceberg discharge events. These cold intervals, known as Heinrich Stadials, are associated with abrupt climate shifts worldwide. Here, we present CO2 measurements from the West Antarctic Ice Sheet Divide ice core across Heinrich Stadials 2 to 5 at decadal-scale resolution. Our results reveal multi-decadal-scale jumps in atmospheric CO2 concentrations within each Heinrich Stadial. The largest magnitude of change (14.0 ± 0.8 ppm within 55 ± 10 y) occurred during Heinrich Stadial 4. Abrupt rises in atmospheric CO2 are concurrent with jumps in atmospheric CH4 and abrupt changes in the water isotopologs in multiple Antarctic ice cores, the latter of which suggest rapid warming of both Antarctica and Southern Ocean vapor source regions. The synchroneity of these rapid shifts points to wind-driven upwelling of relatively warm, carbon-rich waters in the Southern Ocean, likely linked to a poleward intensification of the Southern Hemisphere westerly winds. Using an isotope-enabled atmospheric circulation model, we show that observed changes in Antarctic water isotopologs can be explained by abrupt and widespread Southern Ocean warming. Our work presents evidence for a multi-decadal- to century-scale response of the Southern Ocean to changes in atmospheric circulation, demonstrating the potential for dynamic changes in Southern Ocean biogeochemistry and circulation on human timescales. Furthermore, it suggests that anthropogenic CO2 uptake in the Southern Ocean may weaken with poleward strengthening westerlies today and into the future.
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Affiliation(s)
- Kathleen A Wendt
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97330
| | - Christoph Nehrbass-Ahles
- Climate and Environmental Physics and Oeschger Center for Climate Change Research, University of Bern, Bern CH-3012, Switzerland
- Atmospheric Environmental Science Department, National Physical Laboratory, London TW11 0LW, United Kingdom
| | - Kyle Niezgoda
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97330
| | - David Noone
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97330
| | - Michael Kalk
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97330
| | - Laurie Menviel
- Climate Change Research Centre, Australian Centre for Excellence in Antarctic Science, University of New South Wales, Sydney NSW 2052, Australia
| | | | - James W B Rae
- School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9TS, United Kingdom
| | - Jochen Schmitt
- Climate and Environmental Physics and Oeschger Center for Climate Change Research, University of Bern, Bern CH-3012, Switzerland
| | - Hubertus Fischer
- Climate and Environmental Physics and Oeschger Center for Climate Change Research, University of Bern, Bern CH-3012, Switzerland
| | - Thomas F Stocker
- Climate and Environmental Physics and Oeschger Center for Climate Change Research, University of Bern, Bern CH-3012, Switzerland
| | - Juan Muglia
- Centro Para el Estudio de Sistemas Marinos, El Centro Nacional Patagónico-Conicet, Puerto Madryn U9120ACD, Argentina
| | - David Ferreira
- Meteorology Department, University of Reading, Reading RG6 6ET, United Kingdom
| | - Shaun A Marcott
- Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706
| | - Edward Brook
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97330
| | - Christo Buizert
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97330
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King ACF, Bauska TK, Brook EJ, Kalk M, Nehrbass-Ahles C, Wolff EW, Strawson I, Rhodes RH, Osman MB. Reconciling ice core CO 2 and land-use change following New World-Old World contact. Nat Commun 2024; 15:1735. [PMID: 38443398 PMCID: PMC10915154 DOI: 10.1038/s41467-024-45894-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 02/06/2024] [Indexed: 03/07/2024] Open
Abstract
Ice core records of carbon dioxide (CO2) throughout the last 2000 years provide context for the unprecedented anthropogenic rise in atmospheric CO2 and insights into global carbon cycle dynamics. Yet the atmospheric history of CO2 remains uncertain in some time intervals. Here we present measurements of CO2 and methane (CH4) in the Skytrain ice core from 1450 to 1700 CE. Results suggest a sudden decrease in CO2 around 1610 CE in one widely used record may be an artefact of a small number of anomalously low values. Our analysis supports a more gradual decrease in CO2 of 0.5 ppm per decade from 1516 to 1670 CE, with an inferred land carbon sink of 2.6 PgC per decade. This corroborates modelled scenarios of large-scale reorganisation of land use in the Americas following New World-Old World contact, whereas a rapid decrease in CO2 at 1610 CE is incompatible with even the most extreme land-use change scenarios.
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Affiliation(s)
| | | | - Edward J Brook
- College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Mike Kalk
- College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Christoph Nehrbass-Ahles
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
- National Physical Laboratory, Teddington, UK
| | - Eric W Wolff
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Ivo Strawson
- British Antarctic Survey, Cambridge, UK
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Rachael H Rhodes
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Matthew B Osman
- Department of Geography, University of Cambridge, Cambridge, UK
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Nehrbass-Ahles C, Shin J, Schmitt J, Bereiter B, Joos F, Schilt A, Schmidely L, Silva L, Teste G, Grilli R, Chappellaz J, Hodell D, Fischer H, Stocker TF. Abrupt CO 2 release to the atmosphere under glacial and early interglacial climate conditions. Science 2020; 369:1000-1005. [PMID: 32820127 DOI: 10.1126/science.aay8178] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 07/09/2020] [Indexed: 11/02/2022]
Abstract
Pulse-like carbon dioxide release to the atmosphere on centennial time scales has only been identified for the most recent glacial and deglacial periods and is thought to be absent during warmer climate conditions. Here, we present a high-resolution carbon dioxide record from 330,000 to 450,000 years before present, revealing pronounced carbon dioxide jumps (CDJ) under cold and warm climate conditions. CDJ come in two varieties that we attribute to invigoration or weakening of the Atlantic meridional overturning circulation (AMOC) and associated northward and southward shifts of the intertropical convergence zone, respectively. We find that CDJ are pervasive features of the carbon cycle that can occur during interglacial climate conditions if land ice masses are sufficiently extended to be able to disturb the AMOC by freshwater input.
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Affiliation(s)
- C Nehrbass-Ahles
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland. .,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland.,Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - J Shin
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - J Schmitt
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - B Bereiter
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland.,Laboratory for Air Pollution/Environmental Technology, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - F Joos
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - A Schilt
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - L Schmidely
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - L Silva
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - G Teste
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - R Grilli
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - J Chappellaz
- Institute of Environmental Geosciences (IGE), Grenoble INP, IRD, CNRS, Université Grenoble Alpes, Grenoble, France
| | - D Hodell
- Godwin Laboratory for Palaeoclimate Research, Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - H Fischer
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - T F Stocker
- Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland.,Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
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Nehrbass-Ahles C, Babst F, Klesse S, Nötzli M, Bouriaud O, Neukom R, Dobbertin M, Frank D. The influence of sampling design on tree-ring-based quantification of forest growth. Glob Chang Biol 2014; 20:2867-2885. [PMID: 24729489 DOI: 10.1111/gcb.12599] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/05/2014] [Accepted: 04/01/2014] [Indexed: 06/03/2023]
Abstract
Tree-rings offer one of the few possibilities to empirically quantify and reconstruct forest growth dynamics over years to millennia. Contemporaneously with the growing scientific community employing tree-ring parameters, recent research has suggested that commonly applied sampling designs (i.e. how and which trees are selected for dendrochronological sampling) may introduce considerable biases in quantifications of forest responses to environmental change. To date, a systematic assessment of the consequences of sampling design on dendroecological and-climatological conclusions has not yet been performed. Here, we investigate potential biases by sampling a large population of trees and replicating diverse sampling designs. This is achieved by retroactively subsetting the population and specifically testing for biases emerging for climate reconstruction, growth response to climate variability, long-term growth trends, and quantification of forest productivity. We find that commonly applied sampling designs can impart systematic biases of varying magnitude to any type of tree-ring-based investigations, independent of the total number of samples considered. Quantifications of forest growth and productivity are particularly susceptible to biases, whereas growth responses to short-term climate variability are less affected by the choice of sampling design. The world's most frequently applied sampling design, focusing on dominant trees only, can bias absolute growth rates by up to 459% and trends in excess of 200%. Our findings challenge paradigms, where a subset of samples is typically considered to be representative for the entire population. The only two sampling strategies meeting the requirements for all types of investigations are the (i) sampling of all individuals within a fixed area; and (ii) fully randomized selection of trees. This result advertises the consistent implementation of a widely applicable sampling design to simultaneously reduce uncertainties in tree-ring-based quantifications of forest growth and increase the comparability of datasets beyond individual studies, investigators, laboratories, and geographical boundaries.
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