Deforestation is increasing at an alarming pace. It has grown by 94 percent since August 2019, compared with the previous year’s rate, which had been the highest in a decade. Unlike drier areas in Australia or California, the rainforest can’t catch on fire unless humans cut trees down. The Amazon is being devastated on an industrial scale, and for what? Criminal groups are targeting public lands for low-productivity cattle ranching and mining. Illegal land-grabbing schemes destroy biodiversity and the potentials of bioeconomies, enriching well-connected individuals. Mr. Bolsonaro and his administration encourage it.

Many in Brazil’s elites accepted a Faustian bargain: So long as the government’s economic agenda remains friendly, they look the other way. Now, with all eyes on the pandemic crises, the Amazon and its Indigenous groups face existential threats, while criminals act as if they have permission to plunder.

Oversight and fines for infractions have declined substantially. Last month, Ricardo Salles, the environment minister, fired a director in an enforcement role after he carried out an operation to dismantle illegal mining. The federal government has kept key positions vacant and proposed huge budget cuts to environmental agencies, undermining fire prevention, monitoring and control. The president and his allies support a bill that provides further incentives to deforestation, allowing land grabbers to gain ownership of public lands, including Indigenous territories.

Earlier this year Mr. Bolsonaro announced an Amazon Council headed by the vice president, composed of military and cabinet members. One of its luminaries, Paulo Guedes, the University of Chicago-trained economy minister, prefers populist tropes to an evidence-based approach. At Davos he claimed that poor people destroy the forest because they have to eat. Deforestation relies on the labor of the poor, but it requires large sums of money and leaves behind desolation and social conflict. There is no evidence that it remedies poverty. Mr. Salles has a history of cozying up to infractors, shunning specialists and trolling environmentalists. In public, he often speaks in platitudes and increasingly pays lip service to environmental concerns. In a recently released video of a cabinet meeting, he encouraged weakening environmental protections while the press is distracted by the pandemic.

The vice president, Gen. Hamilton Mourão, has been particularly sensitive to the perception of foreign investors. Recently, in an online event hosted by a major bank, he promised that troops would be mobilized to combat fires and deforestation in the Amazon. On May 6, a federal decree gave the armed forces jurisdiction over those efforts, a measure with potential to sideline independent experts.

We cannot settle for photo opportunities. Mr. Mourão’s Amazon Council does not include representatives from Brazil’s world-class scientific community, nor from the Indigenous and civil society organizations engaged in safeguarding the forest. The vice president toes the party line in his support of the legislative proposal known as “the land-grabbers’ bill,” against the recommendations of specialists, including prosecutors.

Scientists agree that we are nearing a tipping point in deforestation that will lead to the Amazon’s “savannization.” This would have dire consequences not only for the forest, but also for Brazil’s agriculture, urban water and energy supplies, and global temperatures. The ecological and socio-economic impacts are unfathomable, and they include the threat of zoonotic diseases. There is already evidence connecting the destruction of wetlands and rainforest to drought in the São Paulo metropolitan region, halfway across the continent.

If we lose the Amazon, it won’t be for a lack of alternatives. Brazil has the know-how to turn this around. Marina Silva, the minister of the environment between 2003 and 2008, worked to drastically reduce the rate deforestation, which at the time was even higher.