Preprints
https://doi.org/10.5194/cp-2020-142
https://doi.org/10.5194/cp-2020-142

  21 Nov 2020

21 Nov 2020

Review status: a revised version of this preprint was accepted for the journal CP and is expected to appear here in due course.

The remote response of the South Asian Monsoon to reduced dust emissions and Sahara greening during the middle Holocene

Francesco S. R. Pausata1, Gabriele Messori2,3, Jayoung Yun4, Chetankumar A. Jalihal5,6, Massimo A. Bollasina4, and Thomas M. Marchitto7 Francesco S. R. Pausata et al.
  • 1Centre ESCER (Étude et la Simulation du Climat à l’Échelle RÉgionale) and GEOTOP (Research Center on the dynamics of the Earth System), Department of Earth and Atmospheric Sciences, University of Quebec in Montreal, Montreal, Canada
  • 2Department of Earth Sciences, Uppsala University, and Centre of Natural Hazards and Disaster Science (CNDS), Uppsala, Sweden
  • 3Department of Meteorology, Stockholm University, and Bolin Centre for Climate Research, Stockholm, Sweden
  • 4School of GeoSciences, University of Edinburgh, UK
  • 5Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore, 560012, India
  • 6Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, 560012, India
  • 7Department of Geological Sciences and Institute of Arctic and Alpine Research, University of Colorado Boulder, USA

Abstract. Previous studies based on multiple paleoclimate archives suggested a prominent intensification of the South Asian Monsoon (SAM) during the mid-Holocene (MH, ~ 6000 years before present day). The main forcing that contributed to this intensification is related to changes in the Earth’s orbital parameters. However, other key factors likely played important roles, including remote changes in vegetation cover and airborne dust emission. In particular, northern Africa also experienced much wetter conditions and a more mesic landscape than today during the MH (the so-called African Humid Period), leading to a large decrease in airborne dust globally. However, most modelling studies investigating the SAM changes during the Holocene overlooked the potential impacts of the vegetation and dust emission changes that took place over northern Africa. Here, we use a set of simulations for the MH climate, in which vegetation over the Sahara and reduced dust concentrations are considered. Our results show that SAM rainfall is strongly affected by Saharan vegetation and dust concentrations, with a large increase in particular over northwestern India and a lengthening of the monsoon season. We propose that this remote influence is mediated by anomalies in Indian Ocean sea-surface temperatures and may have shaped the evolution of the SAM during the termination of the African Humid Period.

Francesco S. R. Pausata et al.

 
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Francesco S. R. Pausata et al.

Francesco S. R. Pausata et al.

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Short summary
Far afield changes in vegetation such as those occurred over the Sahara during the middle Holocene and the consequent changes in dust emissions can affect the intensity of the South Asian Monsoon (SAM) rainfall the lengthening of the monsoon season. This remote influence is mediated by anomalies in Indian Ocean sea-surface temperatures and may have shaped the evolution of the SAM during the termination of the African Humid Period.