The world will pass the 1.5C warming limit set in the Paris Agreement within a few years, according to the UN Environment Programme's annual Emissions Gap report, published on Wednesday ahead of the COP31 talks in Turkey next month.
Overshoot is now the plan
It is the first edition to call missing the target "imminent and unavoidable". UNEP executive director Inger Andersen said the window has closed, but can be reopened by making the overshoot as brief as possible.
The report looks at how to hold peak warming to 1.7C-1.8C and then bring temperatures back to 1.5C by 2100 using emissions cuts and carbon removal. It warns that every extra fraction of a degree raises the risk of irreversible change in ice sheets, permafrost, ocean circulation and coral reefs.
The gap between pledges and pathways
To follow the lowest overshoot path, global greenhouse gas emissions would need to fall 18% by 2030, 45% by 2035 and 69% by 2040 against 2025 levels. That is close to a 6% cut every year.
Existing pledges would deliver only a 5%-8% cut by 2030 and 11%-15% by 2035, which points to peak warming of about 2.6C. Current policies point to about 2.8C, a higher figure than last year, partly because the United States withdrew from the Paris Agreement and dropped its reduction commitments.
The lowest path also needs renewable electricity capacity to triple by 2035, a coal phase-out by 2040, and large-scale carbon removal that has not been proven at that size.
What COP31 faces
Climate scientist Michael Mann of the University of Pennsylvania, who was not involved in the report, said each additional 0.1C of warming permanently cuts global GDP by roughly 1.2%, more than $1.2 trillion a year, and pushes about 140 million more people into dangerously hot climates.
Kate Marvel of Project Drawdown said a temperature threshold is not the whole story. "The right unit isn't degrees, it's tons," she said, arguing that passing 1.5C shows the world is moving too slowly but does not mean failure is fixed.
Delegates in Turkey will arrive with the report's central number in hand: an 18% cut in four years, against pledges that add up to a fraction of it, and a new task of explaining how temperatures are supposed to come back down.