The 'Brazilian Savannah': Severe Drought and Heat if Deforestation is not Stopped

A grassland landscape with a tree in the foreground
SciDev.Net
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Davos, Switzerland

The 'Brazilian Savannah': Severe Drought and Heat if Deforestation is not Stopped

The Cerrado, the “Brazilian savannah”, will suffer a sharp rise in temperature and droughts if deforestation continues in the region, according to a study presented at the 2022 World Biodiversity Forum held in Davos, Switzerland, from June 26 – July 1, 2022. These climatic changes can make local agriculture unviable and compromise the country's biodiversity and its water supply.

However, a second study by the same group shows that it is possible to reconcile the recovery of this biome through agricultural expansion in already degraded areas, without the need for further deforestation. A biome is a group of ecosystems that share characteristics such as climate, vegetation and fauna.

"Sustainability is no longer an option, but an imperative for the Cerrado," biologist Mercedes Bustamante, lead Researcher from the University of Brasilia, said at a conference during the event.

The Cerrado is the second largest biome in South America, after the Amazon, and one of the largest savannahs in the world, with two million square kilometers. Located in central Brazil, it is an important carbon sink and is home to a wide variety of vegetation, from forests to grasslands, threatened by the expansion of pastures and soybean plantations. It is estimated that 57% of the biome has already been degraded.

Green vegetation with blue sky behind
Vegetation of the Cerrado near quartzite formations in the Pyrenees State Park / Credit: Vinicius Vieira Mesquita via Wikimedia Commons.

In the first study, accepted for publication in the journal Global Change Biology , the researchers modelled three future scenarios for the climate of the Cerrado, based on field research and satellite data on temperature, air humidity, and deforestation, collected between 2006 and 2019.

The first, called “Collapse of the Cerrado”, modelled the climate with the continuation of legal and illegal deforestation in the region until 2050. The current legislation of the Brazilian Forest Code allows deforestation of up to 80% of the area of ​​private properties in the Cerrado.

A second intermediate scenario envisaged only deforestation permitted by law, for a total of 28 million hectares. And a third scenario, more positive, modelled what would happen to the region's climate under a zero deforestation policy combined with the recovery of illegally degraded areas , such as pastures in state conservation areas or in areas of private property that by law have to be preserved.

The results projected severe heat and drought by mid-century if deforestation of any savanna vegetation continues. The temperature increase was 0.68°C in the worst case and 0.31°C in the intermediate scenario. The estimate is only for the region and does not include the expected global warming of more than 1ºC in the period.

"In these scenarios, agricultural activity is compromised," Bustamante explained to SciDev.Net . According to the researcher, this climate change will compromise the rain cycle in the region and the water supply to other important biomes, such as the Pantanal alluvial plain. The drought will cause more forest fires, which threaten local biodiversity and contribute to the emission of greenhouse gases that warm the planet.

The Cerrado is often called the “inverted forest” because its vegetation, although small on the surface, has deep roots that store carbon. These roots also draw water from deep layers of the soil, which is released into the air by the leaves as vapor when they transpire. This vapor forms clouds and rain.

The most affected area in the model is the north of the biome, called Matopiba: an area of ​​more than 9 million hectares that includes parts of the states of Maranhão, Tocantins, Piauí and Bahia. This region is today the best preserved in the biome and also where soybean cultivation is advancing most rapidly .

"This is alarming because this region is already very vulnerable with a very hot and dry climate," Ariane Rodrigues, another author of the study and an environmental scientist at UnB , told SciDev.Net .

The best scenario, with reversal of deforestation, would not fully compensate for the impacts already experienced by the Cerrado, but would reduce them, with a 0.06 °C temperature drop, more water released into the atmosphere, better conditions for animals and plants, and more carbon absorption.

And the good news is that it is possible to reconcile this restoration with some expansion of agriculture in the region without deforesting new areas, says a second study by the group, accepted for publication in the Journal of Applied Ecology .

In the work, the researchers mapped the already degraded areas of abandoned pastures throughout the Cerrado, totaling 60 million hectares, and identified which regions are most suitable for restoration and soybean planting.

They considered the best areas for restoration to be those that already show a return of native vegetation and biodiversity, while the most suitable for agriculture, including soybean planting, are those areas with less biodiversity and that have irrigation infrastructure and production flow.

"A lot of these areas overlap," says Bustamante. “If we transform them all into soybean plantations, we could double the cultivated area. But that doesn't make sense,” he stated.

The mapping will be available free of charge and Bustamante hopes that this information can guide public policies that promote a "more rational" occupation of already deforested areas. 

"We want to show decision makers that there are options," says Bustamante. "We still have areas to plant without deforestation and also areas that can be recovered."

Biologist Rafael Loyola, a scientist at the Federal University of Goiás and executive director of the International Institute for Biodiversity, who was not involved in the study, told SciDev.Net that research like this is essential to guide policymakers.

Loyola, who has also studied the Cerrado for decades, believes there is a mismatch between the policies of conservation policies in Brazil and scientific evidence. “It is absurd to have legislation that still allows such deforestation in the Cerrado,” he concludes.


This story was produced as part of a Biodiversity Media Initiative travel grant to the 2022 World Biodiversity Forum in Davos, Switzerland. It was originally published in Spanish in SciDev.Net on 7 July 2022. It has been translated to English and lightly edited for length and clarity. The Biodiversity Media Initiative is supported by Arcadia — a charitable fund of Peter Baldwin and Lisbet Rausing. 

Banner image: The Cerrado or “Brazilian savannah” is the second largest biome in South America, after the Amazon, with two million square kilometers / Credit: Jonathan Wilkins via Wikimedia Commons.

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