Half of cattle-driven forest clearance in the Brazilian Amazon could have been avoided by the industry-wide implementation of zero-deforestation commitments, according to a study by researchers from a group of leading American and European universities.

In a recent study published in Global Environmental Change, academics found that if these policies had been implemented across all cattle companies operating in the Amazon between 2010 and 2018, deforestation could have been halved, sparing 24,000km2 of forest.

In that time, zero-deforestation commitments successfully reduced cattle-driven forest clearance in the Brazilian Amazon by 15%, or 7,000km2 of forest – equivalent to an area 4.5 times the size of London.

“We’ve shown that zero-deforestation policies are having an important – and measurable – impact in protecting forests, and that with widespread adoption and rigorous implementation they could achieve a lot more,” says Rachael Garrett, Moran professor of conservation and development at the University of Cambridge Conservation Research Institute and senior author of the report.

The production of beef and leather generates more than 70% of all Amazonian deforestation. Deforestation significantly reduces the planet’s capacity to absorb carbon dioxide, threatens biodiversity and risks the livelihoods of indigenous communities.

Deforestation rates have increased in the last decade due to a drop in funding and weaker environmental governance, particularly during Jair Bolsonaro’s presidency.

Brazil’s current president, Luiz Inácio Lula da Silva, has claimed his government will do “whatever it takes” to reach zero deforestation by 2030, a pledge made by more than 100 world leaders during 2021’s Cop26 climate summit.

The fresh research looked at the market share of signatories to the G4 agreement, signed in 2009 by the four major cattle meatpacking companies: JBS, Marfrig, Minerva and Bertin, which was later bought by JBS.

The agreement requires the firms to identify and cut ties with suppliers in the Amazon biome who raise cattle on land cleared after 2009. Crucially, it prohibits all forest clearance, not just illegal deforestation.

The researchers say that their study provides evidence that corporate supply chain policies are effective, despite links between companies with zero-deforestation commitments and farmers often being “opaque, complex or proprietary”.

The study is based on the premise that zero-deforestation policies should be more effective in areas where G4 companies have a greater market share, defined as the number of cattle slaughtered by G4 abattoirs over the total number of cattle slaughtered for each year and each municipality.

Tracking farmers exposed to companies with zero-deforestation policies in the Brazilian Amazon, researchers found that areas where G4 companies controlled more than 50% of the market saw a reduction in land clearance.

They compared rates to a scenario where no G4 companies were present and found a reduction of 7,000km2 of deforestation for cattle in the states of Mato Grosso, Pará and Rondônia.

If G4 coverage had been 100%, the researchers’ model predicts that deforestation would have been reduced by 51%.

Half of cattle-driven deforestation would have continued, the authors claim, due to policy avoidance via “indirect suppliers and other unmonitored market segments”.

The study highlights so-called cattle “laundering”, in which cattle bred and fattened in protected areas are sold to properties outside the protected area. Direct suppliers are farms that raise cattle from birth to slaughter and sell straight to abattoirs, while indirect suppliers sell livestock on to other farms for fattening first.

In 2019 and 2020, several investigations by news organisations and campaign groups found links between JBS suppliers and illegal deforestation. In 2020, JBS and Marfrig announced plans to monitor all their indirect suppliers by 2025, while Minerva said it was already in the process of doing so.

“More needs to be done to improve the rigour of corporate policies and the market coverage of policy adopters, even in relatively well-covered regions such as the Brazilian Amazon,” says Sam Levy, lead author of the report and a researcher at ETH Zurich and New York University.

Other approaches include increased pressure from importing countries and public sector interventions like financial incentives for avoided deforestation or greater governmental influence on companies to adopt and implement zero-deforestation policies.

Earlier this year, non-profit Global Witness flagged the role of financial institutions in funding companies at risk of driving forest clearances, including many firms without any deforestation commitments at all.

According to the new study, a market share approach could be taken for other commodities to track the effectiveness of supply chain policies: “So long as information is available on companies’ policies as well as the quantities bought/processed and regions sourced from, a market share approach can be implemented for any ZDC [zero-deforestation commitment]-targeted commodity/region.”

It adds that the necessary data may be available for commodities included in the Transparency for Sustainable Economies initiative, such as soy, palm oil and cocoa.