Brazil is hosting three weeks of events linked to the COP30 climate summit, hoping to showcase a world still determined to tackle global warming.
That may be tough in a year marked by economic upheaval and cancelled United States commitments.
Business leaders meeting in Sao Paulo are pushing for stronger policies for financing the energy transition, with an open letter on Monday asking governments "urgently" for incentives to adopt renewable energy instead of fossil fuels.
"It's a recognition from the business groups of the importance of multilateralism and the importance of raising ambition," said CEO Maria Mendiluce of the We Mean Business Coalition, which co-ordinated the letter from 35 groups representing 100,000 companies.
In Rio de Janeiro on Monday, mayors, governors and other subnational leaders will attend a Local Leaders summit, which threatens to be overshadowed by protests against the city's bloody crime crackdown a week earlier.
Protesters holding a banner that says in Portuguese 'COP30: Climate can't wait, it's time to act' outside a pre-COP30 meeting in Brasilia, Brazil, on 14 October. Source: AP / Eraldo Peres
Less optimism at this year's event
However, countries and companies may be hard-pressed to project the same optimism that has marked climate diplomacy in recent years.
Today, global co-operation is stagnating amid geopolitical tensions and multiple wars.
An erratic series of US tariffs has upended economic stability worldwide, while US reversals on clean energy policy and climate science have rattled investors.
And while costs for renewable energy have plummeted to below fossil fuels, many countries are juggling competing goals such as food security or developing AI.
Business leaders still hope to press clean energy policies as a priority.
"It makes strong business sense and ensures energy security and competitiveness," said Gonzalo Sáenz de Miera, chairman of the Spanish Green Growth Group.
Brazil's turn as this year's host marks 33 years since the Rio Earth Summit, where countries first signed the United Nations treaty committing to tackling climate change.
The summit has since developed into a major multilateral forum, bringing rich and poor countries together with scientists and civil society to address the climate threat.
But it has so far failed to halt the rise in carbon emissions, though the pace has slowed. About 40 per cent of industrial-era emissions in the atmosphere have been released since the treaty was signed.
In attending the annual summit, leaders typically aim to confirm their country's commitment and to hold one another accountable.
But COP30 is likely to see the lowest attendance by world leaders since 2019, when about 50 heads of state went to Madrid for COP25.
