Hans-Peter Plag
Published on May. 28, 2025, last updated May. 28, 2025.
The “WMO Global Annual to Decadal Climate Update (2025–2029)” was published on May 26, 2025, and this report finds that global air temperatures likely are continuing to be at record levels in the next five years. This has a high potential of increasing risks associated with hydrometeorological hazards such as heat waves, droughts, extreme precipitation and storms. Impacts on societies are likely to increase.
The report projects between 2025 and 2029 the annual averages of global mean near-surface temperature are between 1.2°C and 1.9°C higher than the average over the years 1850-1900. There is also a high 80% chance that at least one of these years will be warmer than 2024, which is the warmest year on record. The report states a 70% chance that the five-year average for the period of 2025-2029 will be more than 1.5°C above the pre-industrial level.
The Guardian also discusses the report today in an article by Jonathan Watts. The author emphasizes that shockingly for the first time, a small likelihood is estimated that before 2030 a year could be 2°C hotter than the preindustrial average.
Another worrying result was published in a study in Global Change Biology. Utilizing satellite data and an algorithm that measures light in sea water, the authors, Thomas W. Davies and Tim Smyth, calculated the depths of photic zones around the world. They found that darkening affected 21% of the global ocean the 2002-2022 period. As a result, in 9% of the ocean the photic zones was 50 m shallower, and in 2.6% of the ocean, the depth reduction reached 100 m. Ian Sample discusses the findings in an article published in The Guardian on May 27, 2025. He emphasizes the potential impacts on the marine biosphere, and he points out that several scientists find these results worrying. No comment is made on the extent this darkening may change ocean heating.
