Preprints
https://doi.org/10.5194/cp-2021-51
https://doi.org/10.5194/cp-2021-51

  11 May 2021

11 May 2021

Review status: this preprint is currently under review for the journal CP.

Holocene vegetation transitions and their climatic drivers in MPI-ESM1.2

Anne Dallmeyer1, Martin Claussen1,2, Stephan J. Lorenz1, Michael Sigl3, Matthew Toohey4, and Ulrike Herzschuh5,6,7 Anne Dallmeyer et al.
  • 1Max Planck Institute for Meteorology, Bundesstrasse 53, 20146 Hamburg, Germany
  • 2Centrum für Erdsystemforschung und Nachhaltigkeit (CEN), Universität Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany
  • 3Climate and Environmental Physics and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
  • 4Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Canada
  • 5Alfred Wegner Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany
  • 6Institute of Environmental Sciences and Geography, University of Potsdam, Germany
  • 7Institute of Biochemistry and Biology, University of Potsdam, Germany

Abstract. We present a transient simulation of global vegetation and climate patterns of the mid and late Holocene using the MPI-ESM (Max Planck Institute for Meteorology Earth System Model) at T63 resolution. The simulated vegetation trend is discussed in the context of the simulated Holocene climate change. Our model captures the main trends found in reconstructions. Most prominent are the southward retreat of the northern treeline that is combined with the strong decrease of forest in the high northern latitudes during the Holocene and the vast increase of the Saharan desert, embedded in a general decrease in precipitation and vegetation in the northern hemispheric monsoon margin regions. The southern hemisphere experiences weaker changes in total vegetation cover during the last 8000 years. However, the monsoon-related increase in precipitation and the insolation-induced cooling of the winter climate lead to shifts in the vegetation composition, mainly between the woody plant functional types (PFTs).

The large-scale global patterns of vegetation almost linearly follow the subtle, approximately linear, orbital forcing. In some regions, however, non-linear, more rapid changes in vegetation are found in the simulation. The most striking region is the Sahel-Sahara domain with rapid vegetation transitions to a rather desertic state, despite a gradual insolation forcing. Rapid shifts in the simulated vegetation also occur in the high northern latitudes, in South Asia and in the monsoon margins of the southern hemisphere. These rapid changes are mainly triggered by changes in the winter temperatures, which go into, or move out of, the bioclimatic tolerance range of individual PFTs (Plant Functional Types). The dynamics of the transitions are determined by dynamics of the Net Primary Production (NPP) and the competition between PFTs. These changes mainly occur on timescales of centuries. More rapid changes in PFTs that occur within a few decades are mainly associated with the time scales of mortality and the bioclimatic thresholds implicit in the dynamic vegetation model, which have to be interpreted with caution.

Most of the simulated Holocene vegetation changes outside the high northern latitudes are associated with modifications in the intensity of the global summer monsoon dynamics that also affect the circulation in the extra tropics via teleconnections. Based on our simulations, we thus identify the global monsoons as the key player in the Holocene climate and vegetation change.

Anne Dallmeyer et al.

Status: open (until 07 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-51', Qiong Zhang, 08 Jun 2021 reply

Anne Dallmeyer et al.

Anne Dallmeyer et al.

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Short summary
Using the comprehensive Earth System Model MPI-ESM1.2, we explore the global Holocene vegetation changes and interpret them in terms of the Holocene climate change. The model results reveal that most of the Holocene vegetation transitions seen outside the high northern latitudes can be attributed to modifications in the intensity of the global summer monsoons.