J. Geophys. Res. Atmos. http://doi.org/c5jk (2019).
Precipitation that maintains the Amazon rainforest occurs in a pronounced wet season related to monsoon dynamics and migration of the intertropical convergence zone. Wet season onset depends on the rainforest itself, which moistens the atmosphere through evapotranspiration and primes the troposphere for deep convective rains. Deforestation could therefore affect the timing of wet season onset and the likelihood of drought, and these aspects play a role in ecosystem health, wildfire risk and the global carbon cycle.
Argemiro Teixeira Leite-Filho and colleagues from the Federal University of Viçosa, Brazil, employed a land-use change database and data from 112 rain gauges to study the relationship between precipitation and deforestation during the past few decades in the southern Amazon. They found that a 50%–60% deforestation rate would correspond to a wet season delay of about one week. In addition, at the beginning or end of the wet season, regions experiencing greater deforestation were more likely to experience dry spells of eight days or longer. This study underscores the cascading impacts of Amazon deforestation on regional hydroclimate, with implications for agriculture and land use.