Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data

<p>Past changes in the inventory of carbon stored in vegetation and soils remain uncertain. Earlier studies inferred the increase in the land carbon inventory (<span class="inline-formula">Δ</span>land) between the Last Glacial Maximum (LGM) and the preindustrial period (...

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Main Authors: A. Jeltsch-Thömmes, G. Battaglia, O. Cartapanis, S. L. Jaccard, F. Joos
Format: Article
Language:English
Published: Copernicus Publications 2019-04-01
Series:Climate of the Past
Online Access:https://www.clim-past.net/15/849/2019/cp-15-849-2019.pdf
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author A. Jeltsch-Thömmes
A. Jeltsch-Thömmes
G. Battaglia
G. Battaglia
O. Cartapanis
O. Cartapanis
S. L. Jaccard
S. L. Jaccard
F. Joos
F. Joos
author_facet A. Jeltsch-Thömmes
A. Jeltsch-Thömmes
G. Battaglia
G. Battaglia
O. Cartapanis
O. Cartapanis
S. L. Jaccard
S. L. Jaccard
F. Joos
F. Joos
author_sort A. Jeltsch-Thömmes
collection DOAJ
description <p>Past changes in the inventory of carbon stored in vegetation and soils remain uncertain. Earlier studies inferred the increase in the land carbon inventory (<span class="inline-formula">Δ</span>land) between the Last Glacial Maximum (LGM) and the preindustrial period (PI) based on marine and atmospheric stable carbon isotope reconstructions, with recent estimates yielding 300–400&thinsp;<span class="inline-formula">GtC</span>. Surprisingly, however, earlier studies considered a mass balance for the ocean–atmosphere–land biosphere system only. Notably, these studies neglect carbon exchange with marine sediments, weathering–burial flux imbalances, and the influence of the transient deglacial reorganization on the isotopic budgets. We show this simplification to significantly reduce <span class="inline-formula">Δ</span>land in simulations using the Bern3D Earth System Model of Intermediate Complexity v.2.0s. We constrain <span class="inline-formula">Δ</span>land to <span class="inline-formula">∼850</span>&thinsp;<span class="inline-formula">GtC</span> (median estimate; 450 to 1250&thinsp;<span class="inline-formula">GtC</span> <span class="inline-formula">±1</span>SD) by using reconstructed changes in atmospheric <span class="inline-formula"><i>δ</i><sup>13</sup>C</span>, marine <span class="inline-formula"><i>δ</i><sup>13</sup>C</span>, deep Pacific carbonate ion concentration, and atmospheric <span class="inline-formula">CO<sub>2</sub></span> as observational targets in a Monte Carlo ensemble with half a million members. It is highly unlikely that the land carbon inventory was larger at LGM than PI. Sensitivities of the target variables to changes in individual deglacial carbon cycle processes are established from transient factorial simulations with the Bern3D model. These are used in the Monte Carlo ensemble and provide forcing–response relationships for future model–model and model–data comparisons. Our study demonstrates the importance of ocean–sediment interactions and burial as well as weathering fluxes involving marine organic matter to explain deglacial change and suggests a major upward revision of earlier isotope-based estimates of <span class="inline-formula">Δ</span>land.</p>
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spelling doaj.art-ce810eab57ec4962a098ddfc5d4992ab2022-12-21T18:57:06ZengCopernicus PublicationsClimate of the Past1814-93241814-93322019-04-011584987910.5194/cp-15-849-2019Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy dataA. Jeltsch-Thömmes0A. Jeltsch-Thömmes1G. Battaglia2G. Battaglia3O. Cartapanis4O. Cartapanis5S. L. Jaccard6S. L. Jaccard7F. Joos8F. Joos9Climate and Environmental Physics, Physics Institute, University of Bern, Bern, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandClimate and Environmental Physics, Physics Institute, University of Bern, Bern, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandInstitute of Geological Sciences, University of Bern, Bern, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandInstitute of Geological Sciences, University of Bern, Bern, SwitzerlandClimate and Environmental Physics, Physics Institute, University of Bern, Bern, SwitzerlandOeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland<p>Past changes in the inventory of carbon stored in vegetation and soils remain uncertain. Earlier studies inferred the increase in the land carbon inventory (<span class="inline-formula">Δ</span>land) between the Last Glacial Maximum (LGM) and the preindustrial period (PI) based on marine and atmospheric stable carbon isotope reconstructions, with recent estimates yielding 300–400&thinsp;<span class="inline-formula">GtC</span>. Surprisingly, however, earlier studies considered a mass balance for the ocean–atmosphere–land biosphere system only. Notably, these studies neglect carbon exchange with marine sediments, weathering–burial flux imbalances, and the influence of the transient deglacial reorganization on the isotopic budgets. We show this simplification to significantly reduce <span class="inline-formula">Δ</span>land in simulations using the Bern3D Earth System Model of Intermediate Complexity v.2.0s. We constrain <span class="inline-formula">Δ</span>land to <span class="inline-formula">∼850</span>&thinsp;<span class="inline-formula">GtC</span> (median estimate; 450 to 1250&thinsp;<span class="inline-formula">GtC</span> <span class="inline-formula">±1</span>SD) by using reconstructed changes in atmospheric <span class="inline-formula"><i>δ</i><sup>13</sup>C</span>, marine <span class="inline-formula"><i>δ</i><sup>13</sup>C</span>, deep Pacific carbonate ion concentration, and atmospheric <span class="inline-formula">CO<sub>2</sub></span> as observational targets in a Monte Carlo ensemble with half a million members. It is highly unlikely that the land carbon inventory was larger at LGM than PI. Sensitivities of the target variables to changes in individual deglacial carbon cycle processes are established from transient factorial simulations with the Bern3D model. These are used in the Monte Carlo ensemble and provide forcing–response relationships for future model–model and model–data comparisons. Our study demonstrates the importance of ocean–sediment interactions and burial as well as weathering fluxes involving marine organic matter to explain deglacial change and suggests a major upward revision of earlier isotope-based estimates of <span class="inline-formula">Δ</span>land.</p>https://www.clim-past.net/15/849/2019/cp-15-849-2019.pdf
spellingShingle A. Jeltsch-Thömmes
A. Jeltsch-Thömmes
G. Battaglia
G. Battaglia
O. Cartapanis
O. Cartapanis
S. L. Jaccard
S. L. Jaccard
F. Joos
F. Joos
Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data
Climate of the Past
title Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data
title_full Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data
title_fullStr Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data
title_full_unstemmed Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data
title_short Low terrestrial carbon storage at the Last Glacial Maximum: constraints from multi-proxy data
title_sort low terrestrial carbon storage at the last glacial maximum constraints from multi proxy data
url https://www.clim-past.net/15/849/2019/cp-15-849-2019.pdf
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