THE speed at which trees are being cleared in the Brazilian Amazon today could have a similar local warming effect to decades of temperature rises driven by climate change. So say calculations on how deforestation will alter temperatures in the region over the next three decades.
Logging has been expanding in Brazil. And the election of populist Jair Bolsonaro as president in January has provoked fears that deforestation could get even worse if he appeases the powerful agribusiness lobby.
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Barry Sinervo at the University of California, Santa Cruz, and his colleagues have calculated that even with current tree losses, local surface temperatures in the Amazon will rise by an average of about 1.5掳C between 2010 and 2050. That will come on top of the 2掳C of warming from climate change that the world is on track for by mid-century (PLoS One, ).
Deforestation affects local temperatures by changing the amount of sunlight reflected and the rates at which water evaporates from vegetation into the atmosphere.
The degree of warming may vary dramatically within the Brazilian Amazon. Some parts of the east, where there is an 鈥渁rc of deforestation鈥� hundreds of kilometres wide and thousands of kilometres long, could see big local temperature rises even if logging is reduced.
In that scenario, where 79,000 square kilometres of trees are cleared by 2050, large tracts of forest won鈥檛 get significantly warmer.
With business-as-usual deforestation, however, in which 606,000 square kilometres of rainforest disappears, local temperature rises could be widespread. An increase in this logging could make matters much worse. 鈥淎ny more deforestation and conversion to agriculture will exacerbate these numbers,鈥� says Sinervo.
