UN report says climate outlook worsened as US emissions rose

A worsening outlook in the UN’s latest assessment

The world is losing ground against climate change, according to a new United Nations Environment Programme update cited by Phys.org. The assessment projects a hotter outcome than the same science team expected a year earlier, even if countries follow through on their current promises to curb heat-trapping emissions.

Under that scenario, the report says Earth would warm a further 2.2 degrees Fahrenheit, or 1.2 degrees Celsius, above current temperatures. That is about 0.2 degrees Fahrenheit, or 0.1 degrees Celsius, higher than the previous year’s projection. The shift may appear small, but the update is significant because it moves the expected result in the wrong direction while governments are meant to be tightening, not weakening, their climate efforts.

The report identifies two reasons for the worse estimate: the formal withdrawal of the United States from the Paris Agreement and revised estimates of historical emissions. It also points to a US increase in emissions during 2025 that outpaced changes in other countries.

US increase outweighed changes elsewhere

The UN update says that, among the 20 largest economies, every country other than the United States either reduced carbon pollution or slowed the growth of emissions from burning coal, oil and gas. The US increase was estimated at 133 megatons of carbon-dioxide equivalent in 2025.

That figure exceeded the combined increases elsewhere. The report says 124 countries raised emissions, while 63 countries, including most European nations, reduced them. Those countries that increased emissions added 189 million tons of carbon dioxide in 2025; the US accounted for 70 percent of that increase, according to the report.

The cited analysis attributes the US rise to increased electricity demand and a rebound in coal-fired power generation. These are consequential findings because power-sector choices affect both near-term emissions totals and the durability of national climate pledges. A return to coal generation can rapidly raise carbon pollution because coal produces substantial emissions when burned for electricity.

Why the Paris withdrawal matters

The Paris Agreement is built around national commitments to reduce emissions. The UN report’s conclusion is not simply that one country’s emissions rose; it is that the US withdrawal has altered the outlook used to assess whether the collection of national pledges can constrain warming.

Climate projections are cumulative: warming depends on the total amount of heat-trapping gases released over time, rather than on a single year alone. That makes both the revised historical-emissions estimates and current emissions changes relevant to the updated result. A deterioration in either measure leaves less room for the world to remain within more ambitious temperature outcomes.

The assessment also highlights a persistent gap between pledges and the level of action required to lower projected warming. Even full implementation of current promises, as described in the report, would still leave the planet on track for additional warming above today’s temperatures. The finding underscores that making commitments is only part of the challenge; policies, energy investment and implementation determine whether emissions decline in practice.

What the update establishes

• The UN assessment projects 1.2 degrees Celsius of additional warming above current temperatures if countries meet their stated emissions-reduction promises.
• That projection is 0.1 degrees Celsius worse than last year’s estimate by the same science team.
• The report cites the US departure from the Paris Agreement and revised historical-emissions estimates as reasons for the change.
• It says US emissions rose by 133 megatons of carbon-dioxide equivalent in 2025, driven by electricity demand and a rebound in coal power.

The report does not present climate progress as a settled trajectory. Instead, its revised projection is a measure of how policy decisions, energy demand and emissions accounting can change the expected outcome. Its warning is especially direct: recent developments have made the projected temperature result worse, not better.

This article is based on reporting by Phys.org. Read the original article.