Lula arrived Tuesday in Egypt's Red Sea resort of Sharm el-Sheikh and went straight into climate diplomacy with meetings with US envoy John Kerry and China's Xie Zhenhua.
The leftist politician, who served as president from 2003 to 2010, is expected to inject much needed momentum into the COP27 climate talks in his first international trip since defeating far-right incumbent President Jair Bolsonaro, who presided over years of rampant Amazon deforestation.
"Brazil is back in the world to debate the climate issue," Lula tweeted late Tuesday. "We will be a source of pride for the world."
Lula is expected to present his plan for "zero deforestation" in a speech Wednesday afternoon at the COP27 conference.
Kerry told a COP27 biodiversity panel on Wednesday that the United States would work with other nations to help protect the Amazon.
"I was pleased last night to meet with president-elect Lula and was really encouraged by the ways in which he talked about for once and for all getting it right ... in order to preserve the Amazon," Kerry said.
"We will work diligently in order to achieve that goal together with our allies, particularly Norway and Germany and other countries that have been deeply committed to this for a period of time."
Under Bolsonaro, a staunch ally of agribusiness, average annual deforestation increased 75 percent compared to the previous decade.
"We need a new sense of hope to build trust and momentum towards a positive outcome at COP27," said Brazilian climate campaigner, Mariana Paoli, Christian Aid's global advocacy lead.
"President Lula's election victory in Brazil has the potential to breathe new life into this process with his progressive agenda that seeks to bring Brazil back to the table and end the disastrous climate policies of his predecessor."
In another boost to the UN climate process, a final communique from world leaders meeting at the Group of 20 talks in Bali, Indonesia included key promises to "pursue efforts" to curb global warming to 1.5 degrees Celsius above pre-industrial levels, a safer limit according to scientists.
The document, which also reiterated a commitment to phase out "inefficient" fossil fuel subsidies over the medium term, was welcomed by observers as a way to galvanise the climate talks as they enter their final days.
The G20 meeting was also the stage of a crucial meeting between US President Joe Biden and China's Xi Jinping, where the two leaders agreed to resume their climate cooperation.
Ani Dasgupta, head of the World Resources Institute, said positive signals from leaders at the G20 "should put wind in the sails" of negotiators in Egypt.
Bolsonaro, who did not attend the G20 summit in Bali, has maintained a low profile since losing the Brazilian election.
While his government has a pavilion at COP27, former steelworker Lula deployed two of his former environment ministers to lay the groundwork for his visit.
One of them, Marina Silva, who is tipped to return to the job when Lula takes office on January 1, said Brazil wants to set an example with Lula's deforestation plan.
Latin America's most populous country grew more isolated under Bolsonaro, analysts say, in part due to his permissive policies towards deforestation and exploitation of the Amazon -- the preservation of which is seen as critical to fighting global warming.
Brazil is home to 60 percent of the Amazon, which spans eight countries and acts as a massive sink for carbon emissions.
Silva promoted the idea of creating a new national authority to coordinate climate action among government ministries, and of pursuing a reforestation target of 12 million hectares (over 29 million acres).
Lula meets Kerry
The incoming administration wants the United States to contribute to the Amazon Fund, considered one of the main tools to reduce deforestation in the planet's biggest tropical forest.
Following Lula's victory, the fund's main contributors, Norway and Germany, announced they would participate again, after freezing aid in 2019 in the wake of Bolsonaro's election.
Colombian President Gustavo Petro and his counterpart Nicolas Maduro of Venezuela presented at COP27 last week an Amazon protection initiative that they hope Brazil will join.
NGOs and Indigenous leaders want Lula to create the first ministry of Indigenous peoples.
Brazilian lawmaker and Indigenous leader Sonia Guajajara urged Lula to "think about social policies with the people".