Climate Dynamics

, Volume 13, Issue 12, pp 865–881 | Cite as

Quantifying the role of biosphere-atmosphere feedbacks in climate change: coupled model simulations for 6000 years BP and comparison with palaeodata for northern Eurasia and northern Africa

  • D. Texier
  • N. de Noblet
  • S. P. Harrison
  • A. Haxeltine
  • D. Jolly
  • S. Joussaume
  • F. Laarif
  • I. C. Prentice
  • P. Tarasov

Abstract.

 The LMD AGCM was iteratively coupled to the global BIOME1 model in order to explore the role of vegetation-climate interactions in response to mid-Holocene (6000 y BP) orbital forcing. The sea-surface temperature and sea-ice distribution used were present-day and CO2 concentration was pre-industrial. The land surface was initially prescribed with present-day vegetation. Initial climate “anomalies” (differences between AGCM results for 6000 y BP and control) were used to drive BIOME1; the simulated vegetation was provided to a further AGCM run, and so on. Results after five iterations were compared to the initial results in order to identify vegetation feedbacks. These were centred on regions showing strong initial responses. The orbitally induced high-latitude summer warming, and the intensification and extension of Northern Hemisphere tropical monsoons, were both amplified by vegetation feedbacks. Vegetation feedbacks were smaller than the initial orbital effects for most regions and seasons, but in West Africa the summer precipitation increase more than doubled in response to changes in vegetation. In the last iteration, global tundra area was reduced by 25% and the southern limit of the Sahara desert was shifted 2.5 °N north (to 18 °N) relative to today. These results were compared with 6000 y BP observational data recording forest-tundra boundary changes in northern Eurasia and savana-desert boundary changes in northern Africa. Although the inclusion of vegetation feedbacks improved the qualitative agreement between the model results and the data, the simulated changes were still insufficient, perhaps due to the lack of ocean-surface feedbacks.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • D. Texier
    • 1
  • N. de Noblet
    • 1
  • S. P. Harrison
    • 2
  • A. Haxeltine
    • 3
  • D. Jolly
    • 4
  • S. Joussaume
    • 1
  • F. Laarif
    • 2
  • I. C. Prentice
    • 4
  • P. Tarasov
    • 2
  1. 1.Laboratoire de Modélisation du Climat et de l’Environnement, CEA Saclay, Bâtiment 709, Orme des Merisiers, F-91191 Gif-sur-Yvette Cedex, FranceFR
  2. 2.Dynamic Palaeoclimatology, Lund University, Box 117, S-221 00 Lund, SwedenSE
  3. 3.Physical Geography, Lund University, S-22100 Lund, SwedenSE
  4. 4.Global Systems Group, Department of Ecology, Ecology Building, S-223 b2 Lund, SwedenSE
  5. 5.Laboratoire d’Océanographie Dynamique et de Climatologie, CNRS/ORSTOM/UPCM, Paris, FranceFR
  6. 6.Department of Geography, Moscow State University, 119 899 Moscow, RussiaRU

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