Using the Mid?Holocene “Greening” of the Sahara to Narrow Acceptable Ranges on Climate Model Parameters

During the early to mid-Holocene vegetation expanded cover much of present-day Sahara. Although driven by a well-understood difference in orbital configuration, general circulation models have generally failed simulate required rainfall increase. One possible explanation is presence systematic biases representations atmospheric convection which might also impact future projections. We employ Bayesian method learn from an ensemble present day and simulations that vary parameters convection, boundary layer cloud schemes. The model can reproduce “Green Sahara” if mixing between convective plumes environment increased upper troposphere relative lower down. This does not appreciably simulation, meaning paleoclimate reconstructions are able narrow constraints on suitable parameter ranges. suggests other uncertain components climate could be targeted this way.