title: A deforestation-induced tipping point for the South American monsoon system.
abstract: The Amazon rainforest has been proposed as a tipping element of the earth system, with the possibility of a dieback of the entire ecosystem due to deforestation only of parts of the rainforest. Possible physical mechanisms behind such a transition are still subject to ongoing debates. Here, we use a specifically designed model to analyse the nonlinear couplings between the Amazon rainforest and the atmospheric moisture transport from the Atlantic to the South American continent. These couplings are associated with a westward cascade of precipitation and evapotranspiration across the Amazon. We investigate impacts of deforestation on the South American monsoonal circulation with particular focus on a previously neglected positive feedback related to condensational latent heating over the rainforest, which strongly enhances atmospheric moisture inflow from the Atlantic. Our results indicate the existence of a tipping point. In our model setup, crossing the tipping point causes precipitation reductions of up to 40% in non-deforested parts of the western Amazon and regions further downstream. The responsible mechanism is the breakdown of the aforementioned feedback, which occurs when deforestation reduces transpiration to a point where the available atmospheric moisture does not suffice anymore to release the latent heat needed to maintain the feedback.
authors.affiliation: Ecole Normale Supérieure, Geosciences Department and Laboratoire de Météorologie Dynamique, Paris, F-75230, France.|Potsdam Institute for Climate Impact Research, Potsdam, 14473, Germany.
authors.forename: Niklas
authors.initials: N
authors.lastname: Boers
authors.affiliation: Potsdam Institute for Climate Impact Research, Potsdam, 14473, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Marwan
authors.affiliation: University of São Paulo, Institute of Physics, São Paulo, 05508-090, Brazil.
authors.forename: Henrique M J
authors.initials: HM
authors.lastname: Barbosa
authors.affiliation: Potsdam Institute for Climate Impact Research, Potsdam, 14473, Germany.|Humboldt University, Department of Physics, Berlin, 12489, Germany.|Nizhny Novgorod State University, Department of Control Theory, Nizhny Novgorod, 603950, Russia.|University of Aberdeen, Institute for Complex Systems and Mathematical Biology, Aberdeen, AB24 3UE, United Kingdom.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kurths
mesh_terms: D003198:Computer Simulation; D003247:Conservation of Natural Resources; D008962:Models, Theoretical; D011891:Rain; D012621:Seasons; D013020:South America; D014329:Tropical Climate