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Model assessment of the possible contribution of increasing marine biogenic aerosol in Late Cenozoic cooling

LI Gao-jun, CHEN Jun, JI Jun-feng, SHENG Xue-fen, LI Tao   

  1. 1. Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, Nanjing 210093, China; 2. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK; 3. Bengbu Branch of China Meteorological Administration, Bengbu 233000, China.
  • Received:2009-06-20 Revised:2009-06-20 Online:2009-06-20 Published:2009-06-20

Abstract: Geochemical model coupled with marine isotopic records of carbon, strontium and osmium indicates a late Cenozoic increase in chemical weathering associated with enhanced physical erosion. Marine bio-productivity is largely promoted by the fertilized oceans in response to the increasing riverine phosphorus input. The increasing biogenic aerosol caused by marine biobooming result in elevated cloud albedo and cloud cover, which would act as a significant negative radiative forcing of about 16.5 W m-2 over the past ~7 Ma that is equivalent to about 13 ℃ global cooling in equilibrium temperature. The increasing atmospheric aerosol also reduces the precipitation efficiency of cloud, which would enable penetration of ocean vapour into high latitudes and ultimately facilitate the accumulation of polar ice sheets.