Overview
- WMO data show January–August 2025 averaged 1.42°C above pre‑industrial levels, extending a run in which every year from 2015 to 2025 ranks in the top eleven.
- Atmospheric greenhouse-gas concentrations rose by an unprecedented 2.3%, with the largest share attributed to India, followed by China, Russia and Indonesia.
- The agency identifies human CO2 emissions as the main driver, noting El Niño has ended after temporarily boosting recent warmth, leaving 2025 somewhat cooler than 2024.
- Indicators signal worsening impacts, including rapid glacier loss, record-warm oceans, below-average Arctic and Antarctic sea ice, and sea levels rising about 4 millimeters per year.
- Early-warning systems now cover 119 countries since 2015 yet about 40% still lack effective protection, and a UNEP assessment projects 2.3–2.5°C of warming by 2100 under fully implemented pledges.