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A coalition of over 250 scientists from 27 countries has delivered a powerful message to Brazilian President Luiz Inácio Lula da Silva, urging bold leadership on phasing out fossil fuels ahead of COP30.

The letter, presented during the ongoing Bonn Climate Conference, was handed in person to COP30 President-designate Ambassador André Corrêa do Lago by climate physicist and Climate Analytics CEO Bill Hare.

The letter, addressed directly to President Lula and also submitted to the Brazilian Presidency in Brasília, calls for an urgent and just transition away from fossil fuels, a measure the scientists say is critical to protecting lives, livelihoods, and the planet.

“This is the most important climate action the world must take,” said Hare. “If Brazil can’t deliver progress on this, history won’t look kindly on its COP30 Presidency.”

The scientists’ appeal is grounded in a decade of rigorous research, including key findings from the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Among their most urgent messages is a 2023 IPCC conclusion: the 1.5°C warming limit is unattainable under the current trajectory of fossil fuel infrastructure.

The letter also warns that continued fossil fuel reliance threatens to reverse decades of global development gains, particularly in efforts to reduce poverty, hunger, and inequality.

“Fossil fuel combustion is at the root of the climate crisis and its devastating impacts,” the letter states. “Only a realistic and urgent energy transition can protect development, fight hunger, and reduce inequality.”

Renowned scientists Dr. Paulo Artaxo, a professor and IPCC member from the University of São Paulo, and Dr. Friederike Otto, an expert in extreme weather from Imperial College London, spearheaded the letter. Their goal: to reinforce Lula’s role as a global climate leader and use Brazil’s Presidency of COP30 to prioritize a full, fair fossil fuel phaseout.

“The science is very clear,” said Artaxo. “We must end fossil fuel use to halt climate change. This letter is our way of supporting President Lula with evidence-based urgency.”

The appeal comes as the planet hits a worrying milestone: surpassing the 1.5°C annual global temperature increase for the first time. The Global Carbon Budget warns that the remaining carbon budget could be depleted in just six years. The scientists caution that decisions made in the lead-up to COP30 will carry generational consequences.

Hare also criticized recent developments in Brazil, noting that the government’s so-called “doomsday” oil auction has opened the Amazon basin to new fossil fuel exploration, sending a contradictory signal just months before COP30 convenes in Belém.

“There could be no clearer warning,” said Hare. “The Amazon is near a tipping point. Continuing fossil fuel expansion while championing climate action cannot coexist.”

As negotiations in Bonn continue, the scientists’ call reinforces what many in civil society, vulnerable nations, and the broader climate community have long demanded: that COP30 must mark a turning point, not just in dialogue, but in definitive, science-aligned action.