By Erika Yarrow-Soden
The State of Global Water Resources 2024 report, an annual publication by the World Meteorological Organization (WMO), documents 2024 as an extraordinary year, shaped by record heat, climate extremes and widespread water-related impacts.
With input from a wide network of hydrological experts, including National Meteorological and Hydrological Services (NMHS), Global Data Centres, members of the global hydrological modelling community, and supporting organisations such as National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), the German Research Centre for Geosciences (GFZ), the World Glacier Monitoring Service (WGMS), the Global Runoff Data Centre (GDRC) and the International Groundwater Assessment Centre (IGRAC), the report seeks to enhance the accessibility and availability of observational data (both through better monitoring and improved data sharing), integrate relevant variables into reporting, and encourage country participation to improve understanding and broaden the reporting of water cycle dynamics.
One of a suite of WMO reports, the annual State of Global Water Resources 2024 report is based on data contributed by WMO members, as well as information from global hydrological modelling systems and satellite observations, and provides an authoritative assessment of global freshwater availability, including streamflow, reservoirs, lakes, groundwater, soil moisture, snow and ice, to help improve decision-making and water security.
WMO says that this latest report – now in its fourth year – is the organisation’s most comprehensive to date, with new information on lakes, reservoirs, precipitation and water quality, supported by increased engagement from WMO Member States in terms of data sharing and advances in methodology and data sources. This data highlights a water cycle that has become increasingly erratic and extreme, swinging between deluge and drought, with the report raising concerns about the cascading impacts of too much or too little water on economies and society. With global surface temperatures reaching 1.55 °C above pre-industrial levels, 2024 was the hottest year in the 175-year observational record. Strong El Niño conditions at the start of the year amplified drought in South America and southern Africa, while other regions faced devastating floods.
Erratic water cycle
The report finds extremes across the water cycle, with rivers, reservoirs, lakes, groundwater and glaciers all showing significant departures from what would be considered ‘normal’. In the case of rivers, around 60% globally showed either too much or too little water, marking the sixth consecutive year of imbalance. There was below-normal discharge across key river basins including the Amazon, São Francisco, Paraná, and Orinoco in South America, and the Zambezi, Limpopo, Okavango and Orange basins in southern Africa.
It was ‘wetter-than-average’ in Central and western Africa, the Lake Victoria basin in Africa, Kazakhstan and Southern Russia, Central Europe, Pakistan and Northern India, Southern Iran, and North-Eastern China. Extensive flooding occurred in West African basins in Senegal, Niger, Lake Chad and Volta, and there was above normal river discharge across Central Europe and parts of Asia, swelling major basins including the Danube, Ganges, Godavari and Indus. A year of contrast and extremes, while parts of Africa, Europe, and Asia were inundated by flooding, South America and southern Africa endured severe drought.
Water security
Reservoir inflows, groundwater, soil moisture and evapotranspiration trends highlighted regional contrasts, with recharge in wetter areas such as parts of Europe and India, but persistent deficits in parts of Africa, the Americas and Australia. Over-extraction of groundwater continued to be a problem in some areas, reducing future water availability for communities and ecosystems and further stressing global water resources. Only 38% of wells (out of 37,406 from 47 countries that submitted groundwater data) had ‘normal levels’, with the majority experiencing unusually low or high levels. The water quality of the 75 main lakes across the globe was impacted because of temperatures ‘above’ or ‘much above’ normal temperatures in July.
Glacial melt
Glaciers saw record ice loss, adding to sea level rise, with widespread glacier loss across all regions for the third consecutive year. The report finds that many small glacier regions have already reached or are about to pass ‘peak water point’ – the point at which a glacier’s melting reaches its maximum annual runoff, after which runoff decreases because of glacier shrinkage. Record mass loss occurred in Scandinavia, Svalbard and North Asia, while some regions like the Canadian Arctic and Greenland periphery saw more moderate losses. Nearer the Tropics, Colombian glaciers lost 5% in 2024.
Advances in satellite observations and modelling systems
Although the State of Global Water Resources 2024 report sets a turbulent scene of extreme weather impacting populations and economies across the globe, it also underscores the potential of satellite-based observations and modelling systems to assist countries – especially those with limited monitoring capabilities and large data gaps – to address water challenges and improve hydrological assessments. Future reports are anticipated to include even more observational data, supported by initiatives like WMO’s Global Hydrological Status and Outlook System (HydroSOS) and Hydrological Observing System (WHOS), and further collaboration with global data centres.
Given the vital importance of water to society, economies and ecosystems, WMO’s State of Global Water Resources report will continue to be a critical benchmark. Reiterating the gravity of the report and the value of the data that it provides, WMO Secretary-General Celeste Saulo said: “The world’s water resources are under growing pressure and – at the same time – more extreme water-related hazards are having an increasing impact on lives and livelihoods. Reliable, science-based information is more important than ever before, because we cannot manage what we do not measure. The WMO’s State of Global Water Resources Report 2024 is part of WMO’s commitment to provide that knowledge. Continued investment and enhanced collaboration in data sharing are vital to close monitoring gaps. Without data, we risk flying blind.”
