Global temperatures could rise by 2.8°C above pre-industrial levels by 2100 under existing government policies, the United Nations Environment Programme warned in a report released on 21 October.
Even if countries fully implement their current climate commitments, the projected increase would reach 2.6°C, exceeding the goals of the 2015 Paris Agreement.
The findings in UNEP's Emissions Gap Report 2026 show that recent national climate pledges have done little to improve the outlook, despite rapid growth in renewable energy and emissions reductions achieved through policies in several countries.
"Overshoot is not surrender," UN Secretary-General António Guterres said in a message accompanying the report, urging governments to accelerate efforts to reduce greenhouse gas emissions.
The Paris Agreement commits countries to keeping global warming well below 2°C while pursuing efforts to limit the rise to 1.5°C above pre-industrial temperatures.
UNEP said limiting warming to 1.5°C without exceeding that threshold, or with only a small temporary overshoot, was no longer a realistic prospect under current conditions.
Its most ambitious scenario instead aims to restrict peak warming to between 1.7°C and 1.8°C around the middle of the century, before bringing temperatures back to 1.5°C or lower by 2100.
The report estimates that such a pathway would have approximately a 50% chance of achieving that outcome.
Reaching it would require global greenhouse gas emissions to fall by 18% from 2025 levels by 2030, 45% by 2035 and 69% by 2040.
Existing national commitments would deliver reductions of only 5% to 8% by 2030 and 11% to 15% by 2035, leaving a substantial gap between planned action and the cuts required.
UNEP said the revised projections were worse than those published last year, partly because of the United States' withdrawal from the Paris Agreement and updated estimates of historical emissions.
Climate plans submitted since the previous report have made almost no difference to projected warming, the agency found.
The United States also contributed disproportionately to the increase in global emissions during 2025.
According to figures cited by the Associated Press, US emissions rose by 133 million tonnes of carbon dioxide equivalent, driven largely by higher electricity demand and increased coal-fired power generation.
That represented approximately 70% of the combined emissions increase among the 124 countries where emissions rose during the year.
UNEP Executive Director Inger Andersen warned that each additional fraction of a degree of warming, and every extra year above the 1.5°C threshold, would increase the risks from extreme weather, including floods, heatwaves and wildfires.
The report nevertheless identified progress in renewable energy and climate policies that have reduced emissions in parts of the global economy.
Since the adoption of the Paris Agreement, renewable electricity capacity has expanded three times faster than previously anticipated, while solar power deployment has grown seven times faster.
UNEP also reviewed more than 220 climate policy evaluations, finding that measures introduced in electricity generation and other sectors had produced measurable emissions reductions.
But those gains have not been implemented widely enough to reverse the global trajectory.
Achieving the report's lowest possible warming pathway would also require removing and permanently storing approximately 320 billion tonnes of carbon dioxide from the atmosphere during this century.
UNEP warned that the scale of carbon removal required faces considerable technological and economic uncertainty.
The findings arrive before the COP31 UN climate conference, scheduled to take place in Antalya, Turkey, from 9 to 20 November.
Governments are expected to examine progress towards existing climate commitments and discuss measures to accelerate emissions reductions, the transition away from fossil fuels and international cooperation.
The report identifies the expansion of renewable energy, improvements in energy efficiency and stronger policies to reduce fossil fuel use as central to narrowing the gap between current commitments and the Paris Agreement's temperature goals.
