Deforestation in Xingu may reduce rainfall in Mato Grosso

Massive deforestation in indigenous lands and protected areas of the Xingu  Basin, Pará and Mato Grosso, Brazil | EJAtlas

Deforestation in the Xingu River region may reduce by 7% the average annual rainfall in the state of Mato Grosso, one of the largest agricultural centers in the world, with more than three million inhabitants and eight hydroelectric plants. During the drought, the impact can reach a reduction in rainfall of 15% of the historical average. The center and northwest of the state are the most affected regions.

These are the findings of the study “Mapping the effect of deforestation on rainfall: a case study of the State of Mato Grosso,” carried out by researchers from the Climate Policy Initiative (CPI) and the Pontifical Catholic University of Rio de Janeiro (PUC-RJ).

This is a new model, made by computers, observing the relationship between rainfall and deforestation. The impact of deforestation can affect rainfall in regions thousands of kilometers away from where it occurred.

CPI’s senior analyst for sustainable infrastructure Rafael Araújo studied the path of clouds formed in the ocean and that feed on water vapor when they pass through the forest. He observed the path of the winds until reaching agribusiness production in Mato Grosso.

“In the same way that it is possible to follow a river upstream until reaching its source, it is possible to follow the direction of the wind to identify its path from the ocean,” explains Mr. Araújo.

“The first step was to understand the relationship between forest and precipitation. We used the entire Amazon rainforest in South America to estimate the relationship. Once we understood the relationship, we simulated different scenarios,” says the economist and author of the study.

The researchers studied the path of the winds in the dry and rainy seasons. “In July, the winds are coming from outside the Amazon, passing through the Northeast region and reaching Mato Grosso. They deliver little rain because there are no trees on the way throwing moisture up,” explains Mr. Araújo. “But in February, the clouds are carried by the Amazon rainforest and arrive in Mato Grosso with a lot of humidity.”

To measure the forest’s contribution to the process, Mr. Araújo considered a scenario in which all 11 Xingu indigenous lands were deforested. The region covers parts of the states of Mato Grosso and Pará. Later, he developed the climate model that relates deforestation and rain. He used monthly data between 1985 and 2020.

“The question we asked was: if the Xingu region is deforested, what will be the loss?” said Juliano Assunção, director of the CPI-RJ. “Then we pursued a simple story: clouds rise in the oceans, receive additional load from the forest and collapse in Mato Grosso,” he explains.

The study shows, for example, that more prolonged droughts may happen, putting Mato Grosso’s agriculture at risk and preventing the sector from having a second harvest in some regions of the state.

“In discussions about climate, the forest is often reduced to a carbon sequestration mechanism and forest loss is only used to account for emissions; however, another important ecological service that deserves greater consideration is the forest’s ability to control rainfall on a continental scale, something that affects agricultural production, power generation and urban water supply,” says the study.

“There are studies indicating the negative impact of climate change on rainfall in Brazil. This is not under our control, but there is a portion of the rain that depends on protecting the Amazon, and this we can control,” says Mr. Araújo.

“The new tool can help governments and populations in the arguments to strengthen conservation efforts,” says the text. The model can be adapted to other regions of Brazil and South America. New developments of the initiative will address the energy and supply sector of cities.

Source: Valor international