Expectations were high this week as Brazil’s new President Luiz Inácio Lula da Silva, took office. Lula campaigned on promises to help the world fight climate change by protecting the Amazon rainforest, which sequesters a large portion of global carbon emissions.

Under his predecessor, Jair Bolsonaro, deforestation in the Brazilian Amazon reached its highest level since 2008, threatening efforts to reduce worldwide emissions and preserve one of Earth’s richest biodiversity hotspots.

Global leaders and scientists are waiting to see whether Lula will be able to fulfil his pledges. In November 2022, at the COP27 international climate summit in Sharm El-Sheik, Egypt, he was greeted with cheers as he proclaimed that “Brazil is back” and committed to reaching net-zero deforestation by 2030.

He will be fighting an uphill battle, say analysts and researchers who spoke to Nature. Several of Bolsonaro’s allies were elected to the Brazilian Congress last year, so Lula will need to forge his own alliances to pass climate legislation. He will also have to contend with Bolsonaro’s legacy, finding ways to reverse actions the former leader took against environmental protection.

“Bolsonaro weakened monitoring systems for protected areas, reduced budgets for environmental institutions” and replaced researchers at those organisations with military staff who had no scientific expertise, says Marina Silva, Brazil’s new environment minister. She had the same role from 2003 to 2008, during Lula’s first and second terms as president.

Under the Bolsonaro administration, there was an “overall policy blackout”, says Silva, who was also part of an advisory group that helped Lula to transition into office after winning the presidency in late October 2022.

Lula has already signed several climate- and environment-related decrees in his first week on the job. One re-establishes the Amazon Fund, an international mechanism frozen by the Bolsonaro administration that finances efforts to reduce deforestation.

Lula also revoked a 2022 edict, signed by Bolsonaro, that sought to expand and legalize small-scale ‘wildcat’ gold mining, which strips land of vegetation, pollutes waterways and is often carried out illicitly in Indigenous territories in the Amazon.

Marina Silva got to work quickly, too, announcing the creation of a National Authority for Climate Security, an office that – if approved by the Brazilian Congress – will oversee the execution and implementation of the country’s climate policy.

According to Natalie Unterstell, president of the Talanoa Institute, a think tank focused on climate policy in Rio de Janeiro, Brazil, even more action is needed to restore Brazil’s climate leadership. The Lula administration should start by restructuring the Ministry of the Environment and Climate Change, she says, and by restoring the mandate of the agencies it houses – all of which have been destabilised over the past four years.

Under Bolsonaro, the budget for Brazil’s environment agencies dropped by more than 70 per cent, compared with 2014 (when the budget was at its peak), leaving it at its lowest level in 17 years.

Another crucial step the new administration should take, Unterstell adds, is to “put law enforcement back in place” to protect against environmental crime.

In 2021, the country issued the lowest number of fines for logging in two decades, according to the Brazilian newspaper O Estado de São Paulo, even though the Amazon experienced its highest rates of deforestation in more than a decade.

The rainforest takes in about one-quarter of all the carbon dioxide absorbed by land on Earth. Research shows, however, that deforestation is transforming the region from a carbon sink into an emissions source, and scientists worry that in about a decade, the Amazon could reach a tipping point – when disrupted rain cycles and biodiversity loss could convert it into a savannah-like area – if logging goes unchecked.

To put Brazil on a path to net-zero deforestation, the new government should start by strengthening surveillance of the rainforest’s health and use the data to influence environmental policy, Unterstell says. Restoring funding and staff to Brazil’s National Institute for Space Research (INPE), which uses satellites to monitor tree cover and greenhouse-gas emissions, and was gutted by Bolsonaro – would be an important step in that direction, she argues.

If Brazil’s new government is to reconstruct the country’s environmental policy, science must play a crucial part, says former INPE director Ricardo Galvão, who, like Silva, was part of the transition team advising Lula. Galvão says that the transition team recommended the creation of an office devoted to the Amazon, to be placed in the Ministry of Science, Technology and Innovation.

Lula followed through on this advice, establishing the Sub-secretariat of Science and Technology for the Amazon during his first day in office, on January 1. The idea is for it to “help oversee scientific development in the region and put forth biodiversity-based sustainable development”, Galvão adds.

This means finding ways to allow economic development to occur in the Amazon without wiping out plant and animal species, by harvesting non-timber forest products such as plant-based oils or fruits, for example.

All of Lula’s climate plans won’t be possible without funding, however, and that’s what scientists will be watching for, says Paulo Artaxo, a physicist at the University of São Paulo. An increase in science and technology funding, as well as a rise in research grants – hopefully within Lula’s first 100 days in office – will be some of the markers of success, Artaxo adds.

Cuts to science budgets have been felt widely throughout Brazil – and beyond. Erika Berenguer, an ecosystems researcher at the University of Oxford, UK, is part of the Sustainable Amazon Network, which collects scientific evidence as a way to strengthen sustainability in the Amazon.

The network, made up of institutions inside and outside Brazil, has had difficulties with staffing and training because of the cuts. “Both benefits and lack of opportunity are shared among us all,” Berenguer says.

Silva is optimistic that the Lula administration will turn things around. As challenging as the current situation is, she says, the new government has a roadmap it can follow: during her stint in the 2000s as environment minister, she created the Action Plan for the Prevention and Control of Deforestation in the Legal Amazon, which helped to slash deforestation by 83 per cent in the region between 2004 and 2012.

The challenges are different this time, but “Brazil knows what to do and how to do it”, Silva says. “We’ll build on that success.”

• A Nature report