RIO DE JANEIRO — The Amazon rainforest in Brazil lost an area about 12 times the size of New York City from August 2018 through July of this year, according to government data released Monday, which shows that deforestation in the biome has shot up significantly since the election of President Jair Bolsonaro.
The 3,769 square miles of forest cover lost during that period represents a 30 percent increase from the previous year and the highest net loss since 2008.
The new deforestation figures, released by Brazil’s National Institute for Space Research, provide the clearest evidence to date that deforestation in the Amazon is on a solidly upward trend on Mr. Bolsonaro’s watch.
Mr. Bolsonaro, who has long argued that conservation policies stymie economic development, has been disdainful of the environmental measures that reduced the Amazon deforestation rate between 2004 and 2012. His government has weakened enforcement of environmental laws by cutting funding and personnel at key government agencies, and it has scaled back efforts to fight illegal logging, mining and ranching.
Environmental activists said Monday’s announcement, while not unexpected, was deeply concerning for the Amazon, the world’s largest rainforest.
“This figure is the direct result of the strategy implemented by Bolsonaro to dismantle the environment ministry, prevent the enforcement of laws, shelve plans previous governments made to curb deforestation and empower, through rhetoric, those who commit environmental crimes,” Climate Observatory, a Brazilian environmental group, said in a statement.
“In a break with what occurred in previous years during which the rate rose, this time the government did not announce any credible measures to reverse the trend,” it said.
Mr. Bolsonaro’s approach to the environment — and the Amazon in particular — came under sharp scrutiny in August as a rash of forest fires, most attributed to humans clearing land, consumed large swaths of the biome. Facing outrage from European leaders and threats of an international boycott of Brazilian exports, the government deployed the military to help contain the blazes.
But the Bolsonaro administration has continued to weaken the agencies tasked with enforcing environmental laws and regulations. And it maintains that industries such as mining and agriculture should have broader access to protected lands, including Indigenous reserves.
The environment minister, Ricardo Salles, said on Monday that the rise in deforestation had started well before Mr. Bolsonaro’s government came to power in January.
He added that the “unlawful economy” in the Amazon, where illegal logging and mining is rife, was largely to blame. “We need strategies to contain that,” Mr. Salles said during a presentation to journalists. He did not outline a detailed plan to combat the trend.
Experts say the damage unfolding in several Brazilian states is causing irreparable harm to the Amazon. The forest is often called the Earth’s “lungs” for its vast capacity to release oxygen and store carbon dioxide, a major cause of global warming. Some experts fear that so much forest will be lost that the area will transform into savanna, which cannot store as much carbon.
“We must remember that the Amazon has been undergoing deforestation for decades,” Oyvind Eggen, the secretary general of the Rainforest Foundation Norway, said in a statement. “We are approaching a potential tipping point, where large parts of the forest will be so damaged that it collapses.”
Gilberto Câmara, the secretariat director of the Group on Earth Observations, a coalition of governments and researchers that share and analyze data to shape public policy, said the growing destruction of the Amazon is doing tremendous damage to Brazil’s image and economic prospects.
“The decision of foreign investors to bring resources to Brazil is increasingly contingent on compliance and rules regarding sustainability,” said Mr. Câmara, a former director of the National Institute for Space Research, the Brazilian agency that tracks deforestation by studying satellite images.
“From the point of view of future generations,” he said, “the loss of biodiversity and the rise of emissions are huge setbacks that will have enormous consequences over the next 10, 15 years and beyond.”
Mr. Bolsonaro and several senior government officials have been dismissive of international criticism over deforestation, arguing that Brazil has done more than many other countries to conserve its forests.
Earlier this year, shortly before the Amazon fires made international headlines, Mr. Bolsonaro said that protecting the environment mattered only to vegans. In August, when Germany said it would devote funds to conservation efforts in Brazil, he suggested that Chancellor Angela Merkel “take that money and use it to reforest Germany” instead.