Six conclusions about a model of the world without the Amazon

Translated by Flora Thomson-DeVeaux

 versão em português

Nearly 20% of the original footprint of the Amazon rainforest has been cut down since the Portuguese arrived in Brazil, 99% of that after 1970. The situation seemed to be under control by 2012, after an anti-deforestation policy was able to reduce annual rates by 84%, but activity has risen since then. In 2018, the deforestation rate reached its highest level in a decade as 7,536 square kilometers of forest were destroyed, according to Brazil’s National Institute for Space Research (INPE, in Portuguese).

The rate for 2019 will only be available at the end of the year, but it appears on track to rise even further. Some specialists have estimated that the affected area may pass the 10,000-km² mark, which would make for the first five-digit result since 2008. According to alerts from INPE, deforestation is up 93%, compared to the same period in 2018.

In this context, a study by American scientists decided to simulate what would happen to the global climate if the forest were turned into pasture, either in whole or in part. The hypothesis may sound apocalyptic, but some studies predict that, if deforestation hits a certain level, Amazonia may lose its ability to regenerate and degrade into a savannah. Specialists disagree about the location of that point of no return, which may be triggered by the deforestation of as little as 20% or as much as 40% of the forest’s original area. Here are some of the main conclusions of the study, which was based on a computational climate model:

• Less rain. One of the most worrisome findings has to do with the drop in rainfall across Brazil. In all of the scenarios included in the model, which simulated the disappearance of 50% to 100% of the Amazon rainforest, coupled with the presence or absence of coordinated activity to decrease greenhouse gas emissions across the world, precipitation will decrease across much of Brazil. Without the Amazon, it will rain, on average, 25% less in Brazil – and that decrease comes on top of the decline in rainfall already predicted for part of the country as a result of global warming.

• Fewer grains. The areas most affected by the reduced rainfall would be Amazonia and part of the Cerrado region in center-west and southeast Brazil, where most of the agricultural commodities that the country exports are grown. Since Brazilian agriculture is largely dependent on rain, this reduced precipitation would cause crop yields to crash. Soybeans, corn, and coffee, which are among the country’s leading exports, would be most affected by the lack of rain.

• Dirtier energy. In a future with less rain, energy production will also be affected. Hydroelectric plants are responsible for 75% of Brazil’s electricity production, and so the country will have to turn to other sources of energy to make up for the shortfall. If the government invests in thermoelectric plants (coal-fired or natural gas), which seems most likely, the country’s energy mix will become dirtier and Brazil will emit more greenhouse gases.

• A hotter Brazil. Without the Amazon – or with only half an Amazon – Brazil will feel temperatures rise. In a scenario in which the whole forest is turned into pasture and the world works to combat global warming, the temperature in the Brazilian North would rise 2.5ºC on top of the 1.5-2.5°C increase that would come even if the Amazon remained intact. If the world keeps on emitting greenhouse gases at current rates, however, temperatures in Amazonia are set to rise between 2.0° and 2.5°C, in addition to the 4° to 5°C predicted by climate models.

• A hotter world. Brazil and the rest of South America would feel the brunt of the additional warming triggered by the transformation of the forest into pastures, but effects would be global. As Amazonian precipitation dried up, average global temperatures would rise another 0.25°C even in a scenario where the world’s nations strive to curb climate change. Thermometer readings would rise significantly at both poles, in Canada, the Middle East, Central Asia, and Australia.

• Adieu, Paris. In all these scenarios, if 50% or 100% of the Amazon forest is turned into cattle pasture, the world can say goodbye to any chance of meeting the goal set by the Paris Agreement, which seeks to limit the rise in the average global temperature since the Industrial Revolution to 2°C or possibly even 1.5°C.

Bernardo Esteves

Repórter da piauí, é apresentador do podcast A Terra é Redonda (Mesmo) e autor dos livros Admirável novo mundo: uma história da ocupação humana nas Américas (Companhia das Letras) e Domingo É Dia de Ciência (Azougue Editorial)

João Moreira Salles

Documentarista, é fundador da piauí. Dirigiu No Intenso Agora, Santiago, Entreatos, Notícias de uma Guerra Particular e Nelson Freire. É autor de Arrabalde: Em Busca da Amazônia (Companhia das Letras)