On the remote impacts of mid-Holocene Saharan vegetation on South
American hydroclimate: a modelling intercomparison
Abstract
Proxy reconstructions from the mid-Holocene (MH: 6,000 years ago)
indicate an intensification of the West African Monsoon and a weakening
of the South American Monsoon, primarily resulting from orbitally-driven
insolation changes. However, model studies that account for MH orbital
configurations and greenhouse gas concentrations can only partially
reproduce these changes. Most model studies do not account for the
remarkable vegetation changes that occurred during the MH, in particular
over the Sahara, precluding realistic simulations of the period. Here,
we study precipitation changes over northern Africa and South America
using four fully coupled global climate models by accounting for the
Saharan greening. Incorporating the Green Sahara amplifies
orbitally-driven changes over both regions, and leads to an improvement
in proxy-model agreement. Our work highlights the local and remote
impacts of vegetation and the importance of considering vegetation
changes in the Sahara when studying and modelling global climate.