WMO Report Highlights Decline in Global Soil Moisture Levels in 2023
On 7 October 2024, the World Meteorological Organization (WMO) released its 2023 State of the Global Water Resources report, emphasizing the profound impacts of climate change on global water resources and offering recommendations for countries to address these challenges. A significant focus of the report is soil moisture, where the International Soil Moisture Network (ISMN), hosted at the ICWRGC, contributed analysis on in-situ moisture trends.
Observed Soil Moisture Trends
The ISMN analysed data from approximately 160 stations globally, each with more than 15 years of continuous records. Soil moisture levels were categorised as below-normal, normal, or above-normal at two depths: near-surface (up to 10 cm) and deeper (up to 0.5 m). In Europe, nearly 50% of near-surface stations recorded below-normal conditions, while in the United States, 81% of stations reported normal or above-normal conditions. Notable regional variations were observed, with July showing a wide range of soil moisture levels across the U.S.
Soil moisture in July 2023 compared with all Julys 2008–2022 (15-year reference period) for the top layer of soil (down to 0.11 m)
Modelled Soil Moisture
The report also incorporated data from three Global Hydrological Models (GHMs), revealing predominantly below-normal soil moisture levels worldwide in 2023. Regions such as North America, South America, North Africa, and the Middle East experienced significantly below-normal levels, particularly from June to August. In contrast, areas such as Alaska, northeastern Canada, India, and northeastern Russia exhibited above-normal soil moisture.
Due to the limited availability of in-situ data, validating the model results was not feasible. These findings underscore the urgent need for expanded and long-term data collection to better understand soil moisture conditions on both regional and global scales.