While warning that breaching the 1.5°C global warming limit would bring irreversible losses that no adaptation initiatives could undo, the United Nations Environment Programme (UNEP) on Wednesday (September 2, 2026), for the first time, set out a detailed “overshoot, peak and decline” pathway.

This is a route under which the world overshoots the 2015 Paris Agreement’s central goal — limiting the rise in average global temperatures to 1.5°C above pre-industrial levels — which a UNEP report said was now unavoidable, but holds the peak as low as possible and then brings temperatures back down below the limit by the end of the century.

The report, Limiting Overshoot, released in Nairobi, said global warming would cross 1.5°C “in the next few years”. Even a scenario in which every country delivers on its national climate plan and net-zero target puts peak warming at 1.8°C, it said. According to the report, current policies point to a rise of about 2.6°C by 2100, with a range of 1.9–3.6°C. The pathway, the report said, “is by no means an acceptable or preferred pathway; it is simply the best remaining option.”

The diplomatic grounds for that framing were laid at the 30th UN Climate Change Conference, COP30, held in 2025 in Brazil’s Belém, where the consensus “Global Mutirão” decision became the first COP text to concede that a temporary overshoot of the 1.5°C limit was likely, given how fast the remaining carbon budget was being spent. At the conference, countries also committed, for the first time, to limiting the size and duration of the overshoot and to closing adaptation gaps, which would require deep, rapid and sustained emission cuts.

Given that cuts alone will no longer suffice, a steep scaling up of nature-based removals such as large reforestation programmes was needed, COP30 CEO Ana Toni said in a statement. UN Secretary-General Antőnio Guterres also released a statement, saying, “This summer’s scorching heat, raging wildfires and deadly floods are a warning of what lies ahead. We must make the overshoot above 1.5 degrees as small and short as possible. That demands an overshoot of ambition.”

Compounding costs

The UNEP report suggested that time spent above 1.5°C carries compounding costs such as faster sea-level rise, coral reef collapse, glacier loss exceeding a quarter of global mass by 2100, declines of up to 14% in global food production by 2050 without effective adaptation, and rising odds of irreversible tipping points in the West Antarctic and Greenland ice sheets, the Atlantic Meridional Overturning Circulation and the Amazon.

Moreover, it gets harder to roll back the effects of a tonne of emitted carbon. The report computed that every five years of continued high emissions adds roughly 0.1°C to peak warming. Reversing that same 0.1°C afterwards means pulling about 220 billion tonnes of carbon dioxide back out of the atmosphere over and above whatever is still being emitted. Very broadly, a single large tree growing for about 30 years can cut out only a tonne of carbon dioxide. Carbon dioxide removal, the report stresses, is needed in addition to, not instead of, emission cuts, and can credibly cool temperatures back to the 1.5°C limit only if peak warming stays well below 2°C. Even the most optimistic scaling up of emission cuts is unlikely to reverse more than a few tenths of a degree this century, the report underlined.

UNEP Executive Director Inger Andersen was explicit that the report is not a concession. “Let’s be very clear, the 1.5 target is still the goal. But now we need to approach it differently from above,” she said.

The report arrives at a moment of uncertainty over whether countries will cut emissions at all. The United States, the world’s largest historical emitter, formally exited the Paris Agreement earlier this year and has also announced its withdrawal from the U.N. Framework Convention on Climate Change, the Intergovernmental Panel on Climate Change and the Green Climate Fund. Separately, the closure of the Strait of Hormuz following the conflict in West Asia has produced what the International Energy Agency calls the largest supply disruption in the history of the global oil market, with output from affected countries down more than 14 million barrels a day. Sustained high energy prices could push governments toward coal and other short-term fossil responses.

Methane targets

The report, in a first for the UN, placed significant stress on methane, which currently contributes about 0.5°C of warming. Cutting it is described as the most effective way to slow warming in the near term. Human activity currently puts out roughly 350–400 million tonnes of methane a year, mostly from fossil fuel operations, livestock, rice paddies, landfills and wastewater. When modellers build the pathways that underpin net-zero targets, they typically assume that about half of this gets cut by mid-century through “cheap, technically easy” interventions such as plugging leaks and venting from oil and gas. But the other half, roughly 150–200 million tonnes a year still being emitted in 2050 from agriculture and waste, is harder to cut; though shaving 60–70 million tonnes from it could reduce temperature rise to the same extent as removing 220 gigatonnes of carbon dioxide from the atmosphere.

Over 155 countries have joined the Global Methane Pledge to cut anthropogenic methane at least 30% below 2020 levels by 2030. India, China, Russia and Iran remain outside it.

The UNEP report co-author Richard Betts of the University of Exeter said, “It is a reality check. We have to live with this warmer world.”

Published – September 02, 2026 12:27 pm IST

In a strategic retreat in the fight against climate change, the United Nations has acknowledged that Earth has lost its chance to prevent some of the worst of global warming’s harms. So now the world must figure out how to get temperatures below the danger zone and back to safety, officials say.

Earth is soon going to exceed the safe temperature threshold agreed upon by the world in the 2015 Paris climate accord because of warming from the burning of coal, oil and gas, according to a bleak first-of-its-kind report issued by the United Nations Environment Programme Wednesday (September 2, 2026).

Instead of giving up, scientists and UN officials recommend trying to limit excessive warming and then bring the temperature back down to the agreed-upon threshold. But it still will mean decades of increased weather-related disasters, rising seas, extinctions and melting ice and glaciers.

“Humanity is speeding past the limit to avoid climate catastrophe,” United Nations Secretary-General António Guterres said.

After a period of over-the-limit warming, the new strategy envisions getting back below the limit by ending fossil fuel use and developing some kind of way to suck industries’ carbon dioxide out of the air.

“It’s a reality check. We have to live with this warmer world,” said report co-author Richard Betts, a climate scientist at the University of Exeter. “But there’s still a lot we can do to limit warming.”

Passing the longtime warming threshold

After the Paris climate accord, the United Nations ordered its climate science arm to study different warming limits. A goal of 1.5 degrees Celsius (2.7 degrees Fahrenheit) above mid-19th-century temperatures became generally accepted after scientists found dramatic impacts that affect people and the planet at 2 degrees Celsius (3.8 degrees Fahrenheit) but not at 1.5 degrees.

The world is now at 1.4 degrees Celsius (2.5 degrees Fahrenheit) above pre-industrial levels, some scientists have calculated. The measure is based on a 20-year average, rather than a single year’s temperatures.

Despite experts saying there’s no way to limit warming to 1.5 degrees, U.N. officials long maintained the 1.5 window was still open. Wednesday’s (September 2, 2026) report finally admitted that the world will cross the 1.5 threshold “in the next few years.” The report said the most optimistic scenario has warming peaking at 1.8 degrees (3.2 degrees Fahrenheit) around mid-century if countries pursue ambitious climate goals, but that governments’ current policies should push temperatures to 2.6 degrees (4.7 degrees Fahrenheit) above pre-industrial levels by 2100.

So instead of preventing warming of 1.5 degrees, now the UN said it wants policymakers to “prepare for and navigate a future” in which the globe crosses that limit and then corrects course and cools temperatures. The report envisions that global temperatures will pass 1.5 “within the next few years,” follow a hump-shaped path of more warming, peak, then gradually cool to below the 1.5 mark, ideally by the end of the century. The report and experts call it “overshoot.” “Let’s be very clear, the 1.5 target is still the goal. But now we need to approach it differently from above,” said UNEP Executive Director Inger Andersen.

The 1.5 limit is not “some magical climate cliff” where it’s just game over, said University of Victoria climate scientist Andrew Weaver, who wasn’t part of the study. “Every tenth of a degree we avoid still means less damage.”

Limiting how high temperatures go past threshold is key

It’s most important to limit the new peak temperature and then reduce the amount of time above 1.5 degrees, Andersen said.

But the world likely will be in that overshoot period for “many, many decades,” Mr. Betts said.

Every five years of delay in reducing emissions adds at least a tenth of a degree to peak warming, said report co-author Joeri Rogelj, a climate scientist at Imperial College London.

“If we act now we can limit overshoot,” the report said. “Not a safe world, but safer than remaining above 1.5 degrees for the long term”.

“This is among the bleakest U.N. climate reports I have read. It carries the unmistakable tone of desperation, frustration and urgency — but not resignation,” Mr. Weaver said.

Climate scientist Bill Hare, CEO of Climate Analytics, said that “although UNEP does a good job of describing the hole we’ve dug ourselves into, it does a poor job of showing us that there’s a way out.”

Adapting to a deadlier, hungrier, thirstier world

Governments need to increase efforts to adapt to worsening warming, which hits the poor hardest, “because some impacts simply cannot be avoided,” Mr. Andersen said.

The report calls this phase “coping and containment.” During this overshoot period, more people will die or get sick because of the worsening climate change and its extreme weather, the report said. Food production will drop, people will go hungry, water shortages will worsen, economies will be hurt, and species like coral will go extinct, the report said.

Although the triggers behind the recent deadly Nepal flooding that came as part of a Himalayan glacier dislodging are complex, Mr. Betts said: “Unfortunately, we do expect to see more of such things, and this is exactly why we need to limit peak warming.” The report warns of “tipping points” with irreversible and cascading effects, including the loss of the West Antarctic and Greenland ice sheets, the loss of the Amazon rainforest and the shutdown of the Atlantic Ocean circulation system that keeps much of Europe warm.

“Some locations might become more or less uninsurable or even uninhabitable,” the report said.

The last phase in overshoot is cooling the planet by removing carbon dioxide from the air and storing it somewhere. The report said the traditional approach to this is planting more trees, but it says planting trees could, at most, shave a tenth of a degree off global temperatures. So the authors said more novel carbon removal approaches will be needed.

Other scientists called that unreliable and expensive.

“We were unable to stop the runaway train of global emissions to avoid 1.5 C of warming,” said Stanford University climate scientist Rob Jackson, who wasn’t part of the report. “Now overshoot scenarios require us to stop the train quickly and to back it up. Is it our best hope? Absolutely. Is it likely? Absolutely not.”

Published – September 02, 2026 12:27 pm IST