For the last 35 years, scientists around the world have collaborated on an annual assessment known as “State of the Climate.” Since 1996, the report has been published in a special issue of the Bulletin of the American Meteorological Society, and this year’s “State of the Climate in 2024” has just been released. The report is a collaborative effort by 600 scientists from 58 countries worldwide, and it features important updates on key climate metrics for the atmosphere, land surface, and oceans, from the polar regions to the tropics.
This year’s SoC report highlights the societal impacts of high atmospheric humidity—which has been rising steadily over the past 50 years. High humidity magnifies the impacts of rising temperatures on human health because sweating is less effective—making it even more difficult to cool down on hot days.
Since 2018, the SoC report’s section on Global Climate has also featured a section on phenology, with PhenoCam data, along with John O’Keefe’s observations at Harvard Forest, playing a key role. The 2025 report also includes an analysis (see figure below) of spring phenological anomalies, calculated by the USA-NPN using Mark Schwartz’s “Spring Index Models” (SI-x) compared against anomalies detected at 10 PhenoCam sites across the lower 48.
