The United Nations Environment Programme's annual emissions-gap update now projects that even if every country fully delivers on the climate pledges it has submitted, Earth will warm about 2.6 degrees Celsius above pre-industrial levels by 2100 — far past the Paris pact's 2-degree ceiling and its preferred 1.5-degree goal.

That pledge-based figure is about 0.1 degrees Celsius worse than the same science team projected a year earlier. If countries simply continue on their current path without new promises, the projection is 2.8 degrees Celsius, unchanged from last year.

The report is blunt about the cause: a worse outcome than expected last year, it says, resulted from the formal US withdrawal from the Paris Agreement and revised estimates of historical emissions.

According to the UNEP report, the United States was the only major economy moving backwards.

All other top-20 emitters reduced their carbon pollution or at least slowed its growth in 2025, while US emissions rose by 133 megatons of CO2 equivalent, driven by increased electricity demand and a rebound of coal power generation.

Of the 400 million tons of carbon dioxide added worldwide by the 124 countries whose emissions increased, 33 percent came from the United States.

Report lead author Anne Olhoff, director of the UNEP Copenhagen Climate Centre, said the US policy shift will likely add one-tenth of a degree Celsius to global temperatures by the end of the century.

The planet already sits at about 1.4 degrees Celsius above pre-industrial times, and UN officials have conceded — again, in this report — that limiting warming to the 1.5-degree goal is no longer achievable.

Officials instead hope to hold warming near 1.8 degrees Celsius and then remove enough carbon dioxide from the air to pull temperatures back down.

United Nations Secretary-General António Guterres said the world is falling 'dangerously short' of even those goals, 'but we have the tools to change course and pull back from the brink.'

Australian climate scientist Bill Hare, whose firm Climate Analytics tracks national plans and who was not part of the UNEP study, said the US is going 'hell-for-leather trying to block renewables while actively promoting and subsidizing dirty coal.'

An extra tenth of a degree sounds tiny, but the scientists quoted around the report argue it is enormous. Hare said it pushes an additional 140 million people into dangerously hot conditions and raises the odds of collapse of the Amazon rainforest or the Greenland and Antarctic ice sheets.

University of Pennsylvania climate scientist Michael Mann said it would shave roughly $1.2 trillion from the global economy.

Those impacts are already visible on the ground: researchers and Anangu traditional owners report that hot droughts at Uluru-Kata Tjuta have killed swathes of desert oaks, mulga and desert heath myrtle, with only 10 percent of pukara surviving after the 2019-20 heat waves, per the research team's reporting on phys.org.

The retreat is playing out in court as well as in diplomacy. On October 5, 2026, the US Supreme Court heard Suncor Energy v.

County Commissioners of Boulder County, which will decide whether local governments can impose tort liability on energy companies such as Suncor and ExxonMobil for climate damage — a case built partly on evidence that Exxon knew fossil fuels' warming risks from internal research dating to 1977, as the FSView reports.

Separately, a federal judge has struck down New York's Climate Change Superfund Act, which sought roughly $75 billion from fossil fuel companies, ruling it is preempted by federal law, per Adirondack Explorer — a one-two blow to the accountability strategy at the very moment the UN report demands faster action.

UNEP Executive Director Inger Andersen said drastically cutting global carbon emissions — by 18 percent by 2030 and 69 percent by 2040 — is the only way back to 'a semblance of a reality that is still largely manageable without major impacts.'

Climate scientist Adelle Thomas, vice chair of a UN impacts assessment who was not part of the study, summed up the message: 'We know what needs to be done. We have the tools to do it.

And delay only makes the challenge more dangerous and more expensive for all.' Some scientists, including Australia's Malte Meinshausen, argue the rest of the world should now push ahead while paying less attention to Washington, since US inaction risks coaxing other nations to ease off too.