Brazil this week pulled out of hosting next year’s United Nations global summit meeting on climate change, the latest signal that Latin America’s largest nation no longer aspires to be an influential player in efforts to mitigate the effects of a warming planet.

The decision leaves the United Nations scrambling to find a new venue for the conference, which was scheduled to take place next November. It comes about a month before the inauguration of president-elect Jair Bolsonaro, who has vowed to empower commercial ventures in the Amazon and other Brazilian biomes while weakening enforcement of environmental laws.

Mr. Bolsonaro’s incoming foreign minister, Ernesto Araújo, a career diplomat, has called the movement to reduce global warming a plot by “Marxists” to stifle the economic growth of capitalist democracies while lifting China.

Brazil in 2009 set ambitious goals to reduce the emission of greenhouse gases and took drastic steps to rein in deforestation in the Amazon. Those initiatives were met with international acclaim and positioned Brazil as one of the most consequential and engaged nations in the effort to reduce climate change.

In a statement, Brazil’s foreign ministry said this week’s decision was made to save money. It also cited the “transition process” as Mr. Bolsonaro prepares to take office.

Diplomats, environmentalists and others who follow the United Nations climate negotiations said the move threatens to mar Brazil’s’ reputation as a leading actor on environmental issues and sustainable development.

Brazil hosted the Earth Summit in 1992 that gave rise to the United Nations climate convention, and the country has been actively engaged in brokering compromises between rich and poor nations grappling over how to take responsibility for lowering greenhouse gas emissions.

“The image of Brazil is at risk,” said Carlos Rittl, executive secretary of the Brazilian Climate Observatory, an environmental group. “Climate and the environment are the only issues where Brazil is a leader in global terms. We are not leaders in world trade, we are not leaders in a geopolitical sense on security issues. But on climate and environment we are leaders, and we are giving that up.”

In recent years, Brazil’s standing as an environmental exemplar has eroded as farmers, miners and cattle ranchers have razed large areas of forest cover in the Amazon, with only occasional push back from the agencies tasked with enforcing environmental laws and regulations.

As a result, deforestation in the Amazon is now once again on the rise. Between August 2017 and July of this year, deforestation in the Amazon rose by nearly 14 percent, according to figures the Brazilian government released last week. That represented the highest loss of forest cover in the Amazon, the world’s largest tropical rain forest, in a decade.

Guy Edwards, a Latin America expert and co-director of the Climate and Development Lab at Brown University, said Brazil’s decision to back out of hosting the summit is unwise in economic terms, since it would mean the country would forgo any investment, business deals and cooperation agreements to advance low carbon growth at the time when Brazil needs an economic boost.

“The irony of the incoming Bolsonaro administration’s decision to cancel the conference is that it will forgo the potentially hefty levels of investment and any number of business deals and cooperation agreements to advance low carbon growth just at the time that Brazil needs an economic boost,” he said.

Manuel Pulgar-Vidal, the former environment minister of Peru, called Brazil’s decision “a bit sad,” and added that it also creates a logistical hurdle for next year’s climate change discussions.

Under the United Nations system, a country from Latin America is supposed to host the summit in 2019. Brazil was the only country in the region to volunteer for the task, which can cost a country as much as $100 million.

Other countries in the region still have time to step in, but it is unclear which might do so. Argentina has held climate summits in the past, but it is hosting this week’s Group of 20 talks and may not want to incur another large expense. Mr. Pulgar-Vidal said it is unlikely that Peru, which spent $72 million to host a climate summit in 2014, would do it again.

“This now puts Latin America in a difficult situation,” Mr. Pulgar-Vidal said.

Alexander Saier, the spokesman for the United Nations Framework Convention on Climate Change, said in a statement that if no countries from Latin America offer to host in 2019, then the conference will be held at the seat of the climate secretariat in Bonn, Germany.

That decision, he said, will be made by the end of next month.

Brazil’s decision not to host comes days after the release of a United States government report issued by 13 agencies warning that failing to take significant measures to slow down climate change would do tremendous damage to the American economy.

The issue will be on the agenda of the G-20 gathering in Buenos Aires this week, where the World Bank, the United Nations and the Organization for Economic Cooperation and Development will be calling on the leaders of the world’s largest economies to lower carbon emissions and overhaul infrastructure development to mitigate the impact of climate change.

Brazil is the latest major influencer on climate change policy to take a radical shift on the issue.

President Trump has said he does not accept the established scientific consensus that climate change is occurring and is primarily the result of human activity. Last year he said he would withdraw the United States from the Paris Agreement, a 2016 compromise agreed to by nearly 200 nations to voluntarily cut planet-warming emissions and keep rising temperatures to below a 2-degree Celsius rise over preindustrial levels.

Australia’s new prime minister, Scott Morrison, also threatened to pull out of the Paris Agreement. His conservative government has since said it will honor its pledges, but the country’s energy policy contains no plans for curbing emissions.

And Poland, which will host climate change talks next month, has invited coal companies to be partners in discussions on how to ratchet down fossil fuel emissions.