The hydrological cycle is spinning out of balance as a result of climate change and human activities, according to a new report from the World Meteorological Organization (WMO) that offers an extensive assessment of global water resources.
Destructive droughts and heavy rains are causing harm, while melting snow and glaciers heighten flood risks and endanger long-term water security.
The UN weather agency's State of Global Water Resources Report 2022 emphasizes the need to better understand freshwater resources and urges a fundamental policy shift. It calls for enhanced monitoring, data sharing, cross-border cooperation, and increased investments to manage water extremes effectively.
"This report offers a comprehensive, and consistent overview of water resources worldwide, highlighting the influence of climate, environmental, and societal changes," said Petteri Taalas, WMO Secretary-General.
Substantiated by field observations, satellite-based remote sensing, and numerical modelling to evaluate global water resources, the WMO State of Global Water Resources Report 2022 offers in-depth data on key hydrological factors like groundwater, evaporation, streamflow, terrestrial water storage, soil moisture, cryosphere (frozen water), reservoir inflows, and hydrological disasters.
Disrupted water cycle
Glaciers and ice cover are retreating before our eyes. Rising temperatures have accelerated - and also disrupted - the water cycle. A warmer atmosphere holds more moisture causing much heavier precipitation episodes and flooding. And at the opposite extreme, more evaporation, dry soils and more intense droughts, explained the WMO chief.
According to UN Water, currently, 3.6 billion people lack access to sufficient water at least a month per year and this is expected to increase to more than five billion by 2050.
Stocktake
Though further research is needed, and more information from regions like Africa, the Middle East and Asia is required, the conclusions made based on data from 273 stations around the globe are straightforward, the Report authors believe.
In the realm of river discharge and reservoir inflow, over 50 per cent of global catchment areas and reservoirs displayed deviations from normal conditions, of which a majority were drier than usual.
There were anomalies in soil moisture and evapotranspiration (transfer of land water into the atmosphere, either by evaporation or through plants) registered throughout 2022.
For instance, Europe experienced increased evapotranspiration and decreased soil moisture during summer. Moreover, droughts on the continent posed challenges in rivers like the Danube and Rhine and even disrupted nuclear electricity production in France due to the lack of cooling water.
Severe droughts impacted also vast regions including the United States, Horn of Africa, Middle East and La Plata Basin in South America.
In Asia, the Yangtze river basin in China faced a severe drought, while Pakistan's Indus river basin witnessed extreme floods. The disaster resulted in at least 1,700 fatalities, with 33 million people affected and nearly eight million displaced.
Africa's hydrological situations are contrasting too. While the Horn of Africa dealt with a severe drought affecting 21 million people's food security, areas such as the Niger basin and coastal South Africa saw above-average discharge and major floods.
On thin ice
In 2022, the snow cover in the Alps remained significantly below the 30-year average, affecting discharge of the major European rivers. The Andes saw declining winter snow, with the lowest amount in 2021 and some recovery in 2022, impacting water supplies in Chile and Argentina. Observations of Georgia's glaciers revealed a doubling of melting rates over recent years.
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Significant glacial melting was observed in the Asian Water Tower, along with changing river run-offs in the Indus, Amu Darya, Yangtze and Yellow River basins, highlighting the deepening influence of climate change on regional water resources.
"This report is a call to action for more data sharing to enable meaningful early warnings and for more coordinated and integrated water management policies that are an integral part of climate action," urged Mr. Taalas.
The report combines input from dozens of experts and complements WMO's flagship State of the Global Climate report.
