The World Meteorological Organization’s “State of the Global Climate 2025” report confirms that the Earth system is undergoing rapid, large-scale changes. Greenhouse gas concentrations reached record highs in 2024, driving an accumulation of excess energy within the climate system. While 2025 was slightly cooler than the record-breaking warmth of 2024 due to a transition from El Niño to La Niña, it remains one of the warmest years on record. Ocean heat content hit a new peak, and the accelerated melting of glaciers and ice sheets continues to contribute to rising global sea levels, creating cascading risks for human and natural systems.
The report highlights that the Earth’s energy imbalance—a new indicator for this year—has become increasingly positive, meaning the planet is trapping more heat than it radiates back into space. Approximately 91% of this excess energy is absorbed by the ocean, which has reached record heat content levels. This warming, combined with the loss of ice on land, is driving a long-term rise in global mean sea levels. Furthermore, the ocean has absorbed nearly 29% of anthropogenic carbon dioxide emissions over the past decade, a process that buffers some climate effects but simultaneously leads to ocean acidification, threatening marine ecosystems and biodiversity.
Atmospheric concentrations of carbon dioxide, methane, and nitrous oxide reached their highest levels in hundreds of thousands of years during 2024. This increase in greenhouse gases is the primary driver of climate change, resulting in severe weather and climate events throughout 2025. These events, including intense heatwaves, floods, droughts, and tropical cyclones, have caused significant displacement and undermined food security globally. The report emphasizes that vulnerable communities, particularly in low- and middle-income regions, are disproportionately affected by these cascading disasters, which strain local capacities and complicate recovery efforts.
The report also examines the intersection of climate change and human health, specifically focusing on the expansion of dengue fever and the dangers of chronic heat stress. Higher temperatures are increasing the climate suitability for dengue transmission, while heat stress poses a critical risk to the global workforce, particularly in agriculture and construction. The WMO stresses the urgent need for integrated climate services, such as early warning systems, to help decision-makers move from reactive responses to proactive prevention. Strengthening these services is essential to protecting lives and safeguarding development gains in an increasingly warming world.