UN Report: The World Will Overshoot 1.5°C — and U.S. Emissions Jumped Most in the G20

The world will warm past 1.5°C. That concession, long dreaded and long resisted, is now formal: the United Nations Environment Programme's Emissions Gap Report 2026, released Wednesday, October 21, says the goal is no longer to prevent the overshoot but to keep it as small and as short as possible — and then bring temperatures back down by 2100.

The report, titled The Point of Return, singles out the United States. U.S. greenhouse gas emissions rose by about 133 million metric tons of carbon dioxide equivalent in 2025 — an increase that far exceeded any other country's, according to AFP's reporting on the report. NPR reported that the United States was the only major economy where planet-warming pollution increased dramatically last year, leaving it tied with Russia for the highest per-person emissions among G20 members.

From Holding the Line to Coming Back Down

The chance of holding warming to 1.5°C with no or limited overshoot "is now gone," UNEP wrote in a companion explainer. In its place, the report describes a "lowest possible" overshoot pathway in which warming peaks at 1.7 to 1.8°C around mid-century and returns to 1.5°C or below by 2100, with about a 50 percent chance.

That pathway is steep. Global emissions would need to fall 18 percent by 2030, 45 percent by 2035 and 69 percent by 2040, all compared with 2025 — cuts of about 5.7 percent a year, sustained for a decade and a half. If every country fully delivered its current climate pledge, by contrast, emissions would drop only 5 to 8 percent by 2030 and 11 to 15 percent by 2035. The gap between those two sets of numbers is, quite literally, the emissions gap the report is named for.

"Overshoot Is Not Surrender"

UN Secretary-General António Guterres framed the shift in a message accompanying the report. "Overshoot is not surrender," he said, according to UN News — language aimed at preventing the concession from becoming an excuse for inaction. The difference between a peak of 1.7°C and a peak well above 2°C is measured in heat waves, floods, wildfire seasons and sea-level rise that American communities will either experience in manageable form or in catastrophic one.

For U.S. readers, the report connects two things often discussed separately: domestic energy choices and the global temperature path. The findings land weeks before the COP31 climate summit in Antalya, Türkiye, where the second Global Stocktake begins — the formal process by which countries are supposed to ratchet up their ambitions. The United States will arrive at that summit as the report's central cautionary example: the biggest economy in the world, and the one whose pollution rose the most.

None of the report's pathways are predictions; they are choices rendered in arithmetic. The overshoot is now expected. Its size, its duration and its consequences remain, as the report takes pains to argue, substantially within human control — if the steep part of the curve is climbed on schedule, starting now.

What Comes Next

The report's arithmetic also reframes the domestic debate. The same week the UN was quantifying the U.S. emissions increase, American officials were defending domestic energy policy on cost and reliability grounds, and states and cities were tallying the local costs of heat, flood and fire. The two ledgers — the cost of cutting emissions and the cost of not cutting them — are the twin columns of the argument the country will now have under new assumptions: not whether the world passes 1.5°C, but by how much, for how long, and who pays.