State of Global Water Resources
World Meteorological Organization (WMO) has recently published its first State of Global Water Resources report which 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.
The report says that all regions of the world saw water extremes last year — both floods and droughts — and billions of people had insufficient freshwater. “The impacts of climate change are often felt through water – more intense and frequent droughts, more extreme flooding, more erratic seasonal rainfall and accelerated melting of glaciers – with cascading effects on economies, ecosystems and all aspects of our daily lives,” said WMO head Petteri Taalas at the launch of the report.
Following are the key highlights of the report:
Focus of the report
The report focuses on three major areas:
- Streamflow: Volume of water flowing through a river channel at any given time.
- Large areas of the globe recorded dryer than normal conditions in 2021, compared to the average of the 30-year hydrological base period.
- Persistent drought in South and South-East Amazon, and basins in North America including the Colorado, Missouri and Mississippi river basins.
- Ethiopia, Kenya and Somalia have faced several consecutive years with below-average rainfall, causing a regional drought.
- Less Discharge by River: In Africa, rivers such as the Niger, Volta, Nile and Congo had less-than-normal discharge in 2021. Similarly, rivers in parts of Russia, West Siberia and in Central Asia had lower than average discharge in 2021.
- Above-normal river discharge in some Northern American basins, the North Amazon and Southern Africa (Zambezi and Orange), as well as China (the Amur River Basin) and northern India.
- Terrestrial Water Storage (TWS): All water on the land surface and in the sub-surface.
- In 2021, terrestrial water storage was classified as below normal (in comparison to average calculated from 2002-2020) on the West coast of the USA, in the central part of South America and Patagonia, North Africa and Madagascar, Central Asia and the Middle East, Pakistan and north India.
- It was above normal in the central part of Africa, the northern part of South America, specifically the Amazon basin, and the northern part of China.
- Overall, the negative trends are stronger than the positive one
- Hotspots are exacerbated by over-abstraction of groundwater for irrigation.
- The melting of snow and ice also has a significant impact in several areas including Alaska, Patagonia and the Himalayas.
- The cryosphere (frozen water): Cryosphere (glaciers, snow cover, ice caps and, where present, permafrost) is the world’s biggest natural reservoir of freshwater.
- Mountains are often called natural “water towers” because they are the source of rivers and freshwater supplies for an estimated 1.9 billion people.
- Changes to cryosphere water resources affect food security, human health, ecosystem integrity and maintenance, and lead to significant impacts on economic and social development. Such changes also cause hazards such as river flooding and flash floods due to glacier lake outbursts.
- With rising temperatures, the annual glacier run-off typically increases at first, until a turning point, often called ”peak water”, is reached, upon which run-off declines.
Some 3.6 billion people face inadequate access to freshwater at least one month per year, the report said. That is forecast to rise to more than five billion by 2050.
Between 2001 and 2018, around 74 percent of all natural disasters were water-related, according to UN studies. And this report further showed that in 2021, all regions saw devastating water extremes.
There were record-breaking floods in western Europe and the Amazon, while water levels in rivers in Paraguay and southern Brazil dropped to an all-time low.
Major river basins in the Americas and central Africa saw water volumes shrink. Rivers in northern India and southern Africa saw above-average increases.
Terrestrial water storage – all water on the land surface and in the subsurface – shrank more than it grew, the report added. Negative hotspots included Patagonia, the Ganges and Indus headwaters, and the southwestern United States.
“Some of the hotspots are exacerbated by (over-extraction) of groundwater for irrigation. The melting of snow and ice also has a significant impact in several areas, including Alaska, Patagonia and the Himalayas,” the WMO said.
The world’s biggest natural reservoir of freshwater is the cryosphere – glaciers, snow cover, ice caps and permafrost – and changes to this reservoir affect food production, health and the natural world, the report said.
Around 1.9 billion people live in areas where drinking water is supplied by glaciers and snow melt but these glaciers are melting increasingly fast, it stressed.
It urged authorities to speed up the introduction of drought and flood early warning systems to help reduce the impact of water extremes.
- Invest in filling the capacity gap in collecting data at the national level.
- Increase sharing of hydrological data at the international level.
- Development of end-to-end drought and flood early-warning systems.
- Working together as a global hydrological community on developing annual State of Global Water Resources, etc.
- The long-term projections of glacier run-off and the timing of peak water, are key inputs to long-term adaptation decisions.
The idea is to inform climate adaptation and mitigation investments as well as the United Nations campaign to provide universal access in the next five years too early warnings of hazards such as floods and droughts.
In expert estimation as well as the popular imagination, we must brace for a water crisis as the fumes we emit warm up the world. Adapting to climate change, thus, requires us to track global water resources. The WMO report tells us how we are placed. Or, rather, how precariously so. The report offers an overview of river-flow volumes, apart from major floods and droughts, and also identifies ‘hotspots’ of change in freshwater storage, with our cryosphere of snow and ice in the spotlight for its vulnerability to melting in the global heat-trap created by our gas emissions. Since shrunken polar caps and rising sea levels have been familiar tropes, last year’s data might seem a bit out of place at first glance. In 2021, large parts of the planet were unusually dry, according to the report. Some of this can be pinned on La Niña, an oddity that pops up every few years to disrupt wind and rain patterns, but is largely an outcome of global warming, whose deprivations of water could get extremely severe as we go along. For countries like Pakistan, too little water could turn out to be a bigger worry than too much of it over the next few decades.
The scarcity dashboard that we must watch closely is that of terrestrial water storage (i.e. on the land’s surface and just under it). Last year’s data clubs north India and Pakistan among the regions marked as ‘below normal’ in comparison with their 2002-2020 average, with a vast zone of severe groundwater depletion common to both. The Gangetic and Indus systems also feature on the WMO’s ‘hotspot’ list of rapid deterioration. Both originate in the Himalayas, but differ in their cryospheric outlook: the former system’s flow is fed mostly by rain and far less by ice-melt, which spells both less scope for warming-led river spates in the future and a lower likelihood of thinning out. Of course, we have our own water audits, but the WMO has given us a welcome wider view. Its new report should push us to rescue the subcontinent’s northern water table, even engage India in aqua talks to that end.
The writer is a member of staff.