Joint Seminar: Regional climate changes due to three decades of Amazonian deforestation

Over the past three decades, more than 20% of the Amazon rainforest has been cleared.  This deforestation has implications for climate.  In the 1980s, the characteristic spatial scale of deforestation in the Brazilian state of Rondonia was of the order of a few kilometers. This small-scale deforestation led to increases in thermally triggered convection, regional cloudiness, and precipitation frequency.  However, more recent deforestation affects larger scales (tens to hundreds of kilometers), at which our old understanding of the atmospheric response to deforestation may break down. Here, I present a new multi-decadal study of the climatic impacts of Amazonian deforestation using satellite observations and numerical simulations. I report a regime shift in the hydroclimate of Rondonia associated with increasing scales of deforestation, with western Rondonia gradually becoming cloudier and wetter than eastern Rondonia. I explain this transition using numerical simulations, and find that a deforestation-induced change in surface roughness, rather than a change in surface thermal forcing, is the key driver of the observed hydroclimatic shift. This study illustrates the strong scale-sensitivity of the climatic response to Amazonian deforestation, and that deforestation is already sufficiently advanced to have pushed regional climate past a critical threshold.




15:15 h


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


David Medvigy, Department of Biological Sciences, University of Notre Dame, USA


Victor Brovkin

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