Transient simulations of Holocene atmospheric carbon dioxide and terrestrial carbon since the Last Glacial Maximum

Abstract. When the climate is reconstructed from paleoevidence, it shows that the Last Glacial Maximum (LGM, ca. 21 000 yr ago) is cold and dry compared to the present-day. Reconstruction also shows that compared to today, the vegetation of the LGM is less active and the distribution of vegetation was drastically different, due to cold temperature, dryness, and a lower level of atmospheric CO2 concentration (185 ppm compared to a preindustrial level of 285 ppm). In the present paper, we investigate the influence of vegetation change on the climate of the LGM by using a coupled atmosphere-ocean-vegetation general circulation model (AOVGCM, the MIROC-LPJ). The MIROC-LPJ is different from earlier studies in the introduction of a bias correction method in individual running GCM experiments. We examined four GCM experiments (LGM and preindustrial, with and without vegetation feedback) and quantified the strength of the vegetation feedback during the LGM. The result shows that global-averaged cooling during the LGM is amplified by +13.5 % due to the introduction of vegetation feedback. This is mainly caused by the increase of land surface albedo due to the expansion of tundra in northern high latitudes and the desertification in northern middle latitudes around 30° N to 60° N. We also investigated how this change in climate affected the total terrestrial carbon storage by using offline Lund-Potsdam-Jena dynamic global vegetation model (LPJ-DGVM). Our result shows that the total terrestrial carbon storage was reduced by 597 PgC during the LGM, which corresponds to the emission of 282 ppm atmospheric CO2. In the LGM experiments, the global carbon distribution is generally the same whether the vegetation feedback to the atmosphere is included or not. However, the inclusion of vegetation feedback causes substantial terrestrial carbon storage change, especially in explaining the lowering of atmospheric CO2 during the LGM.

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Simulated influence of carbon dioxide, orbital forcing and ice sheets on the climate of the Last Glacial Maximum

Nature ◽

10.1038/29695 ◽

1998 ◽

Vol 394 (6696) ◽

pp. 847-853 ◽

Cited By ~ 169

Author(s):

Andrew J. Weaver ◽

Michael Eby ◽

Augustus F. Fanning ◽

Edward C. Wiebe

Keyword(s):

Carbon Dioxide ◽

Last Glacial Maximum ◽

Ice Sheets ◽

Glacial Maximum ◽

Orbital Forcing ◽

Last Glacial ◽

The Last Glacial Maximum ◽

The Last Glacial

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A data-based re-appraisal of the terrestrial carbon budget at the last glacial maximum

Global and Planetary Change ◽

10.1016/0921-8181(93)90008-c ◽

1993 ◽

Vol 8 (4) ◽

pp. 189-201 ◽

Cited By ~ 58

Author(s):

E VANCAMPO ◽

J GUIOT ◽

C PENG

Keyword(s):

Last Glacial Maximum ◽

Carbon Budget ◽

Glacial Maximum ◽

Terrestrial Carbon ◽

Last Glacial ◽

The Last Glacial Maximum ◽

The Last Glacial

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Modelling Global Vegetation Patterns and Terrestrial Carbon Storage at the Last Glacial Maximum

Global Ecology and Biogeography Letters ◽

10.2307/2997548 ◽

1993 ◽

Vol 3 (3) ◽

pp. 67 ◽

Cited By ~ 110

Author(s):

I. Colin Prentice ◽

Martin T. Sykes ◽

Michael Lautenschlager ◽

Sandy P. Harrison ◽

Olga Denissenko ◽

...

Keyword(s):

Carbon Storage ◽

Last Glacial Maximum ◽

Glacial Maximum ◽

Vegetation Patterns ◽

Terrestrial Carbon ◽

Last Glacial ◽

Global Vegetation ◽

The Last Glacial Maximum ◽

The Last Glacial

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Global peatland area and carbon dynamics from the Last Glacial Maximum to the present – a process-based model investigation

Biogeosciences ◽

10.5194/bg-17-5285-2020 ◽

2020 ◽

Vol 17 (21) ◽

pp. 5285-5308

Author(s):

Jurek Müller ◽

Fortunat Joos

Keyword(s):

Last Glacial Maximum ◽

Carbon Sources ◽

Glacial Maximum ◽

Last Glacial ◽

Northern Latitudes ◽

Transient Simulations ◽

Net Uptake ◽

Gains And Losses ◽

The Last Glacial Maximum ◽

The Last Glacial

Abstract. Peatlands are an essential part of the terrestrial carbon cycle and the climate system. Understanding their history is key to understanding future and past land–atmosphere carbon fluxes. We performed transient simulations over the last 22 000 years with a dynamic global peat and vegetation model forced by Earth system model climate output, thereby complementing data-based reconstructions for peatlands. Our novel results demonstrate a highly dynamic evolution with concomitant gains and losses of active peatland areas. Modeled gross area changes exceed net changes several fold, while net peat area increases by 60 % over the deglaciation. Peatlands expand to higher northern latitudes in response to warmer and wetter conditions and retreating ice sheets, and they are partly lost in midlatitude regions. In the tropics, peatlands are partly lost due to the flooding of continental shelves and are regained through nonlinear responses to the combined changes in temperature, precipitation, and CO2. Large north–south shifts of tropical peatlands are driven by shifts in the position of the intertropical convergence zone associated with the abrupt climate events of the glacial termination. Time slice simulations for the Last Glacial Maximum (LGM) demonstrate large uncertainties in modeled peatland extent (global range from 1.5 to 3.4 Mkm2, million square kilometers) stemming from uncertainties in climate forcing. The net uptake of atmospheric CO2 by peatlands, modeled at 351 GtC since the LGM, considers decay from former peatlands. Carbon uptake would be misestimated, in particular during periods of rapid climate change and subsequent shifts in peatland distribution, when considering only changes in the area of currently active peatlands. Our study highlights the dynamic nature of peatland distribution and calls for an improved understanding of former peatlands to better constrain peat carbon sources and sinks.

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Coupled climate–carbon cycle simulation of the Last Glacial Maximum atmospheric CO<sub>2</sub> decrease using a large ensemble of modern plausible parameter sets

Climate of the Past ◽

10.5194/cp-15-1039-2019 ◽

2019 ◽

Vol 15 (3) ◽

pp. 1039-1062

Author(s):

Krista M. S. Kemppinen ◽

Philip B. Holden ◽

Neil R. Edwards ◽

Andy Ridgwell ◽

Andrew D. Friend

Keyword(s):

Carbon Isotope ◽

Last Glacial Maximum ◽

Glacial Maximum ◽

Meridional Overturning Circulation ◽

Terrestrial Carbon ◽

Large Ensemble ◽

Last Glacial ◽

The Impact ◽

The Last Glacial Maximum ◽

The Last Glacial

Abstract. During the Last Glacial Maximum (LGM), atmospheric CO2 was around 90 ppmv lower than during the pre-industrial period. The reasons for this decrease are most often elucidated through factorial experiments testing the impact of individual mechanisms. Due to uncertainty in our understanding of the real system, however, the different models used to conduct the experiments inevitably take on different parameter values and different structures. In this paper, the objective is therefore to take an uncertainty-based approach to investigating the LGM CO2 drop by simulating it with a large ensemble of parameter sets, designed to allow for a wide range of large-scale feedback response strengths. Our aim is not to definitely explain the causes of the CO2 drop but rather explore the range of possible responses. We find that the LGM CO2 decrease tends to predominantly be associated with decreasing sea surface temperatures (SSTs), increasing sea ice area, a weakening of the Atlantic Meridional Overturning Circulation (AMOC), a strengthening of the Antarctic Bottom Water (AABW) cell in the Atlantic Ocean, a decreasing ocean biological productivity, an increasing CaCO3 weathering flux and an increasing deep-sea CaCO3 burial flux. The majority of our simulations also predict an increase in terrestrial carbon, coupled with a decrease in ocean and increase in lithospheric carbon. We attribute the increase in terrestrial carbon to a slower soil respiration rate, as well as the preservation rather than destruction of carbon by the LGM ice sheets. An initial comparison of these dominant changes with observations and paleoproxies other than carbon isotope and oxygen data (not evaluated directly in this study) suggests broad agreement. However, we advise more detailed comparisons in the future, and also note that, conceptually at least, our results can only be reconciled with carbon isotope and oxygen data if additional processes not included in our model are brought into play.

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