State of Global Water Resources 2021

WMO has published its first State of Global Water Resources report in order to assess the effects of climate, environmental and societal change on the Earth’s water resources. The aim of this annual stocktake is to support the monitoring and management of global freshwater resources in an era of growing demand and limited supplies.

The report gives an overview of river flow, as well as major floods and droughts. It provides insights into hotspots for changes in freshwater storage and highlights the crucial role and vulnerability of the cryosphere (snow and ice).

It shows how large areas of the globe recorded drier than normal conditions in 2021 - a year in which precipitation patterns were influenced by climate change and a La Niña event. The area with below-average streamflow was approximately two times larger than the above-average area, in comparison to the 30-year hydrological average.

Currently, 3.6 billion people face inadequate access to water at least a month per year and this is expected to increase to more than 5 billion by 2050. Between 2001 and 2018, UN-Water reported that 74% of all natural disasters were water-related. The recent UN climate change conference, COP27, urged governments to further integrate water into adaptation efforts, the first-time water has been referenced in a COP outcome document in recognition of its critical importance.

The first edition of the report looks at streamflow – the volume of water flowing through a river channel at any given time. It also assesses terrestrial water storage - all water on the land surface and sub-surface and the cryosphere (frozen water). 

It highlights the lack of accessible verified hydrological data. WMO’s Unified Data Policy seeks to accelerate the availability and sharing of hydrological data, including river discharge and transboundary river basins information. 

The information and accompanying maps are largely based on modelled data (to achieve maximum geographical coverage) and remotely sensed information from NASA’s GRACE (Gravity Recovery and Climate Experiment) mission for terrestrial water storage. The modelled results were validated against observed data, wherever available).

The lack of accessible verified hydrological data is highlighted in the report. WMO’s Unified Data Policy seeks to accelerate the availability and sharing of hydrological data, including river discharge and transboundary river basins information.