Brazil’s government approved on Monday exploratory drilling by state-run oil company Petrobras near the mouth of the Amazon River.

The move has been presented by the government as a technical step to assess energy potential, but environmental groups and scientists warn that it poses significant risks to one of the world’s most sensitive marine and coastal ecosystems.

The environmental regulator Ibama granted Petrobras a licence to carry out exploratory drilling in block FZA-M-059, located in deep water about 175 kilometres off the coast of Amapá state. The Equatorial Margin extends from Brazil’s border with Suriname towards the country’s north-eastern coastline and is believed to hold large oil and gas reserves. Petrobras said the well is for exploratory purposes only and that no oil production will take place during the five-month campaign.

The approval, coming just weeks before COP30, has drawn scrutiny from environmentalists and climate analysts who argue that Brazil’s decision undermines its climate leadership ahead of talks focused on reducing fossil-fuel use. Government officials, however, have defended the decision, saying it followed all legal and technical procedures. Energy Minister Alexandre Silveira described the Equatorial Margin as “the future of Brazil’s energy sovereignty” and pledged that operations would meet the highest environmental standards.

Environmental researchers and non-governmental organisations have repeatedly highlighted the hazards of drilling in the region, where strong ocean currents, complex seabed conditions and ecologically rich estuaries and mangroves make operations particularly risky. The mouth of the Amazon supports an abundance of marine life, including spawning grounds for fish and migratory routes for marine mammals. Experts warn that seismic testing and drilling noise could harm wildlife, while a potential oil spill would be exceptionally difficult to contain and could devastate coastal ecosystems and local fishing communities.

In recent months, Ibama has requested additional information from Petrobras regarding its emergency response and wildlife protection plans, following concerns raised in technical reviews. Petrobras has said it has complied with all requirements and conducted emergency drills as part of the licensing process. Company executives described the authorisation as a milestone after years of regulatory preparation and investment delays.

If the drilling identifies commercially viable oil or gas deposits, Petrobras would still need to complete further appraisal work, new environmental assessments and additional permits before any production could begin — a process likely to take years and face continued public and legal scrutiny. If no significant reserves are found, the campaign will conclude without production but will leave an environmental footprint in an area of high ecological importance.

The project has also reignited debate about Brazil’s broader energy strategy. Environmental campaigners and Indigenous groups argue that pursuing new fossil-fuel frontiers near the Amazon contradicts Brazil’s global climate commitments and jeopardises the health of the Amazon delta, on which many coastal communities depend. Supporters of the project, meanwhile, contend that exploring the Equatorial Margin is essential for national energy security and economic growth.

For now, Petrobras’s licence authorises only a limited, non-producing drilling phase. Yet the operation will serve as a test of Brazil’s ability to balance economic ambition with environmental responsibility at a moment when its climate credibility faces close international scrutiny.

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