- Collecting data from the last 40 years, researchers have observed increased temperatures and more severe droughts in the Matopiba region, which encompasses parts of Maranhão, Tocantins, Piauí and Bahia states.
- A transition zone between the Cerrado and the eastern Amazon, the Matopiba is the largest area of contact between forest and savanna in the tropics; in the last two decades it has become one of the main fronts for the expansion of grain cultivation in Brazil.
- According to the researchers, the increased frequency of hot and dry days in the region results from an interaction between global climate change and the advance of deforestation.
- In the near future, environmental changes can harm agribusiness itself, putting Brazilian food security at risk.
In the transition zone between the eastern Amazon and the Cerrado, an interaction between climate change and agricultural expansion may be resulting in increased temperature and reduced rainfall. This is one of the main conclusions of a study conducted by Brazilian and foreign researchers.
This transition zone, known as Matopiba since it encompasses parts of the states of Maranhão, Tocantins, Piauí and Bahia, is the largest area of contact between forest and savanna in the tropics. The Cerrado predominates in 91% of the region, while the remaining 9% is composed of patches of Amazon Rainforest and Caatinga vegetation. In the last 20 years, this area has become an important agricultural frontier for Brazil.
According to the general coordinator of the research, José Marengo, from the National Center for Monitoring and Early Warning of Natural Disasters (CEMADEN) and first author of the study, the objective of the work was to evaluate if what is occurring in the eastern Amazon happens in the Matopiba region. “And, in fact, we observed that it does. In the region where the new agricultural frontier is being implemented, similar changes are happening to what is observed in the eastern Amazon,” he says.
For the study, the researchers used different data sets, including rainfall, temperature, evapotranspiration and vegetation indexes for the period from 1981-2020. “We observed that in the Matopiba region, especially in the western portion of Piauí and Bahia states, there is an increasing tendency for more severe droughts to occur, intensified by the increase in temperature in the region,” says researcher Ana Paula Cunha, from CEMADEN, who also participated in the research.
The team also found that the largest warming and drought trends in tropical South America during the last four decades were observed precisely in this transition region between Amazonia and the Cerrado. “The replacement of natural vegetation cover by areas destined for agriculture and livestock, together with climate change, may have contributed to the intensification of drought events in that area, especially in the zone known as Matopiba,” says Cunha.
According to her, the results of the work show an increase in the frequency of days without rain and a decrease in the volume of precipitation, besides a delay in the beginning of the rainy season, inducing a greater risk of forest fires during the transition from the dry to the humid period. “These findings provide evidence of increasing climate pressure in this area, which may put global food security at risk, and of the need to reconcile agricultural expansion and the protection of natural tropical biomes,” she says.
Marengo, for his part, draws attention to the fact that these results do not point to the future, but are already occurring. “We found that the region is not only vulnerable to what may occur in the future, but also to what is happening in the present,” he explains.
On the road to savannization
In their paper, the researchers state that the Amazon “savannization” hypothesis suggests that this new balanced state becomes more likely as the climate gets warmer and drier, deforestation advances and fires become more frequent. According to them, the expected result of this interplay of processes is a contraction of the dense, humid forests into a Cerrado-like biome.
For the team, the current economic scenario continues to conspire against the Amazon, giving greater importance to agricultural commodities such as soy, meat and tropical timber than to standing forests. “The agricultural development of the Matopiba region in the transition zone is an example of this,” says Marengo. “To prioritize the expansion of deforestation-free agriculture in the region, it is essential to increase the productivity of pastures, along with incentives for the direct expansion of crops on already converted land.”
The authors of the paper further conclude that the dangerous climate trends detected in the transition zone “may put at risk the natural vegetation processes of the Cerrado and consequent ecosystem services, which may affect agriculture in the area“.
“Matopiba has emerged and partially consolidated as a Brazilian government-backed program for the expansion of agribusiness,” says Marengo. “This represents a move away from Amazon policies in response to strong opposition to deforestation in the region,” he adds.
The study predicts, however, that the processes of environmental change driven by socioeconomic growth in the Matopiba region will in turn be greatly affected by climate change. The gradual increase in annual temperature and water deficit will lead to a longer and hotter dry season with a high frequency of very hot days. “Since soybean productivity is affected by rainfall deficits, the drought trend can reduce the crop’s productivity, putting food security and the Brazilian economy at risk,” Marengo warns.
In other words, for the researchers, the changes already observed in the study are critical and can put at risk the food security of both Brazil and even the world. “Soy is the main feed commodity produced in the Brazilian Cerrado,” says Marengo, “and the consequences of climate change and deforestation in the Amazon and Cerrado could put an end to this agribusiness boom.”
Banner image: Corn cultivation in the Cerrado. Image by Wenderson Araujo/Trilux.
This story was reported by Mongabay’s Brazil team and first published here on our Brazil site on June 21, 2023.