Greenhouse gas levels hit new record highs in 2025: UN

Greenhouse gas concentrations in the atmosphere rose to new record highs in 2025, locking in climate impacts that will persist for centuries to come, the United Nations said Tuesday. From 2024 to 2025, the global average concentration of CO2 rose by 2.8 ppm -- smaller than the record surge from 2023 to 2024 of 3.6 ppm.