UN Report Says US Policy Shift Is a Leading Driver of Worsened Global Climate Projections
A new United Nations Environment Programme report released Wednesday projects that if all countries fulfill their current climate commitments, the world will warm 2.6 degrees Celsius above pre-industrial levels by 2100 — about one-tenth of a degree Celsius more than last year's projection. The report attributes that deterioration in part to the United States' formal withdrawal from the Paris Agreement and a documented rise in US carbon emissions in 2025. The US accounted for approximately 70% of the net emissions increase among the 124 countries that raised their output last year.
The United Nations Environment Programme's annual emissions gap report, released Wednesday, found that global warming projections have worsened since last year, with the United States singled out as a primary driver of the setback. The report states that the US increase of 133 megatons of CO2 equivalent in 2025 "far exceeded that of all other countries," driven by higher electricity demand and a rebound in coal power generation, while most other major economies in the top 20 reduced emissions or slowed their growth.
The report's lead author, Anne Olhoff, director of the UNEP Copenhagen Climate Centre, said the shift in US policy will likely add one-tenth of a degree Celsius to global temperatures by the end of the century. Scientists not involved in the report said the methodology was sound. University of Pennsylvania climate scientist Michael Mann said that extra increment would cost the global economy roughly $1.2 trillion, while Climate Analytics CEO Bill Hare said it would push an additional 140 million people into dangerously hot conditions and increase the risk of collapse of the Amazon rainforest or polar ice sheets.
Both temperature scenarios described in the report — 2.6 degrees Celsius if all national pledges are met, and 2.8 degrees Celsius on the current trajectory without pledges — exceed the Paris Agreement targets of below 2 degrees Celsius and preferably 1.5 degrees Celsius. UN officials have previously acknowledged that the 1.5-degree target is no longer achievable, and the report notes that current efforts fall short even of a revised goal of limiting warming to approximately 1.8 degrees Celsius before drawing carbon back down over time.