Extreme weather events and severe droughts pushed global carbon dioxide emissions higher in 2025 by forcing power grids to rely more heavily on fossil fuels when clean energy sources like wind and water faltered. According to the authors of the newly released report, temperature swings and dry spells significantly boosted demand for heating while simultaneously cutting into the electricity generated by hydroelectric dams and wind turbines. This combination created a nearly 90 million tonne increase in emissions that otherwise could have been avoided.
The report states that “drought conditions in several regions, particularly in Europe and across Central and South America, reduced hydropower output, further contributing to the increase in carbon dioxide (CO2) emissions as the shortfall was largely met by fossil fuels.” It further estimates that “the net impact of weather-related factors – including temperature variations and shortfalls in hydropower and wind – pushed up CO2 emissions from the combustion of fossil fuels by around 90 million tonnes in 2025.”
In simple terms, when nature does not provide enough rain to fill reservoirs or enough wind to turn turbines, utility companies must make up the difference by burning more natural gas and coal to keep the lights on. At the same time, unusually cold winters in some parts of the world forced people to use more energy for heating, which added even more pressure to the system. Because these weather-driven shortages happened in several major regions at once, the global total of planet-warming gases went up despite the record-breaking growth of solar power.
The report “Global Energy Review 2026” was published by the International Energy Agency in France in April 2026. Prepared by the IEA’s Energy Modelling Office under the direction of Laura Cozzi, the comprehensive study was led by authors Alex Martinos and Thomas Spencer.
