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Roads associated with mining in the Amazon cause significant environmental damage

The impact caused by roads created to provide access to mines can be 60 times greater than that caused by the mines themselves

Bridge on a dirt road near a gold mining area in the Amazon rainforest

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The planned exploitation of 242 mineral deposits in the National Reserve of Copper and Associated Minerals (RENCA), which is spread across nine federal and state conservation units on the border between the states of Pará and Amapá, would require 183,000 kilometers (km²) of Amazon rainforest to be deforested to make way for mines. Another 7,600 km², an area equivalent to seven cities the size of Belém, would be deforested for the paving of 1,463 km of roads needed to reach these mines.

By analyzing land occupation history in the northern Amazon, scientists from the University of São Paulo (USP), Brazil, and the University of Queensland, Australia, concluded that native vegetation loss resulting from the construction of roads associated with the mines could be 40 to 60 times greater than the impact of the mines themselves. Assessments of the environmental impacts of mining should therefore be expanded to include analyses of the damage caused by the infrastructure necessary for their operation.

“Indirect impacts, which accumulate over time, are not usually evaluated in licensing processes and other procedures for opening new mines,” points out environmental engineer Juliana Siqueira-Gay, project manager at Instituto Escolhas and lead author of the study that made the findings, published in the scientific journal Nature Sustainability in July. “New roads laid for mines in the Amazon could also encourage more illegal mining, logging, and land grabbing, in addition to uncontrolled urbanization.” Siqueira-Gay toured the RENCA region in 2019 as part of her PhD, completed at USP’s Polytechnic School in July 2021.

The region is under pressure to open up to mining. In August 2017, a decree (No. 9147) was issued to close the reserve, which would have facilitated research and mineral exploration in the region, but social pressure led to its revocation a month later. “Since it is a decree, it could be brought into force again at any time,” says USP mining engineer and geographer Luis Enrique Sánchez, one of the authors of the article and a supervisor to Siqueira-Gay during her doctorate. “Federal and state governments need to analyze road and electricity transmission lines plans, basically the entire infrastructure, before suspending or approving projects of this nature,” emphasizes the researcher.

The topic soon came back to the fore: in 2019, Senator Lucas Barreto asked for the decree closing the RENCA reserve to be reissued. The Brazilian House of Representatives is currently discussing Bill 191/2020, which would authorize mining and other extraction activities in indigenous territories, while Draft Resolution 14/2022 in the Senate aims to create a parliamentary caucus supporting mining in the Legal Amazon.

Great pantherGold deposit exploited by mining company Mina Tucano, which was fined in 2021 for polluting rivers in the Pedra Branca do Amapari region of AmapáGreat panther

Mining in the Amazon can alter the rainforest within a radius of up to 70 km, according to a 2017 study published in Nature Communications, led by ecologist Laura Sonter of the University of Queensland, who co-supervised Siqueira-Gay’s research and is also an author of the latest article. In other countries, the impact of similar activities is much smaller. According to a paper published in the journal Conservation Science and Practice in July 2021, a newly approved 88 km road that will cut through the Harapan rainforest on the island of Sumatra, Indonesia, for transporting coal from a mine is expected to result int he loss of 30 to 40 km² of forest.

To assess the direct and indirect environmental damage of mining, Siqueira-Gay examined the transformations caused by mineral exploitation in the areas around the RENCA reserve, such as Pedra Branca do Amapari and Serra do Navio, both in the state Amapá, from 2004 to 2014. “All the scenarios we developed based on the history of territorial occupation are bad, since deforestation advances through areas of high biological importance,” she says. The engineer and her colleagues created five scenarios to predict the environmental impact over the next 30 years, based on more or less protected area being opened up to mining. One considered the exploitation of 170 mineral deposits in sustainable use conservation units, which would lead to the loss of 131 km² of native vegetation; the roads between them would cause 5,900 km² of deforestation. In another, the exploitation of just eight authorized mineral deposits on indigenous land in the RENCA region would result in 4,254 km² of indirect deforestation, 60 times more than caused directly.

When created in the middle of the rainforest, a road can create many problems. One of them is that they split areas in half, which has consequences for biodiversity. “The isolation of plant and animal populations in one area increases species vulnerability and can contribute to the local extinction of some species,” explains Jean Paul Metzger, an ecologist from USP’s Institute of Biosciences and coauthor of the study. “In addition, greater exposure to the sun, wind, and disturbances caused by human activity at the edges of these fragments can change the microclimate and the behavior of animals in the forest.” Metzger believes the environmentally less harmful alternative would be to open mines near others that already exist in the region, reducing the need for new roads, and farther from areas of biological richness known as hotspots. “It is also important, when necessary, to prohibit construction alongside the roads and limit the times and speeds at which vehicles can use them,” he suggests.

Geographer Carlos Souza Jr. of the Institute for Humans and the Environment in the Amazon (IMAZON), who was not involved in the study, agrees with Metzger, noting that although legal mining is important to the economy, its expansion needs to be well planned. “Even in the worst-case scenario projected in this study, the impacts are underestimated, because for every new road opened legally, there are several unofficial ones created for illegal purposes. And these new roads open up new fronts for deforestation beyond the reach of the planned roads,” he points out. A study he participated in, the results of which were published in the journal Remote Sensing in July, identified that of 3.46 million kilometers of road crossing 40% of native vegetation in the Legal Amazon in 2020, three million kilometers were not official roads.

The USP researchers consider it important to draw up a plan that takes into account the regional—and not just local—effects of mining and seeks to permanently preserve areas of native vegetation, with no possibility of withdrawing the protections. “Assessing regional impacts is already being discussed in the mining sector,” says Cláudia Salles, sustainability manager at the Brazilian Mining Institute (IBRAM). According to her, any changes will rely on the “involvement of all actors, especially the public sector.” When asked about the conclusions of the study, Brazil’s Ministy of the Environment (MMA), Ministry of Mines and Energy (MME), and National Mining Agency (ANM) had not responded by the time of writing.