ISTANBUL

UN Secretary-General Antonio Guterres said Thursday that the world has failed to prevent global temperatures from breaching the critical 1.5 degrees Celsius (2.7 degrees Fahrenheit) threshold, warning a temporary overshoot is now inevitable.

"The hard truth is that we have failed to ensure we remain below 1.5 degrees," Guterres told leaders at the Belem Climate Summit in Brazil. "Science now tells us that a temporary overshoot beyond the 1.5 limit – starting at the latest in the early 2030s – is inevitable."

The UN chief warned even temporary breaching would have "dramatic consequences," exposing billions to unlivable conditions.

Guterres said the World Meteorological Organization confirmed emissions reached another record high last year and continued rising in 2025.

Current national climate plans would lead to above 2.0 degrees of warming even if fully implemented, he said, calling this outcome "moral failure – and deadly negligence."

Political will lacking

Despite acknowledging clean energy progress, with renewables overtaking coal as the world's largest electricity source and investors pouring $2 trillion into clean energy in 2024, Guterres said the obstacle is "political courage," noting that scientists say it is still possible to keep the 1.5-degree goal "within reach."

"Too many leaders remain captive to these entrenched interests," he said, noting fossil fuels still receive vast subsidies and political support while companies spend billions on lobbying, "deceiving the public, and obstructing progress."

Guterres urged countries to accelerate fossil fuel phase-out, reach net zero by 2050, and achieve sustained net-negative emissions to pull temperatures back below 1.5°C before the century's end.

He demanded that developed countries mobilize $300 billion annually and demonstrate a "clear and credible path" to reaching $1.3 trillion yearly in climate finance for developing countries by 2035, as agreed at COP 29 in Azerbaijan's capital Baku.

"Let us be clear: the 1.5°C limit is a red line for humanity," Guterres said. "No one can bargain with physics. But we can choose to lead – or be led to ruin."

The two-day summit in Brazil's northern city brings together heads of state and government, ministers, and leaders of international organizations to discuss urgent climate change issues and commitments. The summit is part of the official events of the UN Climate Change Conference (COP30), which will take place from Nov. 10 to 21.