Climate change: How can water be managed sustainably?

The summer of 2022 was one of the warmest on record¹. While record temperatures were reached from the United States to Iran, the average temperature in Europe during August was 1.72°C higher than the same month in the period 1991-2020². These phenomena, which are destined to become increasingly intense and frequent, have massive repercussions on humanity’s most precious commodity: water. Adapting water management to this new situation is a key issue when it comes to meeting the needs of both local populations and agriculture, which currently consumes nearly 80% of the world’s water resources.

More than a third of the world’s population suffered from water stress in 2022. On current trends, the UN predicts that it could affect half the world’s estimated 10 billion people by 2050³. Due to population growth and increasing urbanisation, the demand for water is expected to increase by more than 30% by 2050. The subject is even more important as it encompasses a range of different problems. For example, by 2100, two thirds of the glaciers in the Himalayas and the Hindu Kush could have melted – with the inevitable repercussions for Asia’s major rivers, from the Ganges to the Mekong⁴.

Agriculture: changing the model to meet the water challenge 

Agriculture is obviously one of the sectors hardest hit by global warming and climate change as it still relies primarily on rainfall. Four out of every five cultivated hectares around the world depend on it. Any reductions – or increases – in rainfall are major threats that could destroy entire harvests.

This was the case even before the rapid rise in global warming witnessed in recent years. A study in the journal Environmental Research Letter⁵ has shown that the severity of the impact of droughts and heatwaves on agricultural production has almost tripled in 50 years. While the drop in production was 2.2% over the 1964-1990 period, it reached 7.3% between 1991 and 2015. The first victims are the crops that rely most on irrigation – cereals, and to a lesser extent vegetables, vines and fruit. For these areas, the effects are potentially devastating. In the Horn of Africa (Somalia, Ethiopia and Kenya), more than 16 million people are at risk of famine. While the worst drought in 15 years is affecting California, there are also warning signs for a vast area stretching from the Strait of Gibraltar to north-east China, via Africa. China, for example, could see its rice harvest fall by 10% to 20% this year, according to the financial agency Fitch⁶.

However, action can be taken, with one of the priority areas being the yields achieved by farmers. One of the keys to improving this is a better selection of crops, in favour of those able to avoid or tolerate water stress. In West Africa, a number of traditional crops such as fonio, millet and cowpea have reappeared in recent years.  Similarly, a growing number of farmers in France are replacing their maize crops with plants from sub-Saharan Africa such as sorghum.

Faced with the risk of drought, another solution is to look at the diversity of crops and to take an agroecological⁷ approach. The aim here is to preserve biodiversity and natural resources by combining traditional knowledge and know-how with scientific research in areas including agronomy, economics and sociology. Creating synergies between cultivated plants, animals and trees makes it possible to increase production, while limiting the use of chemical fertilisers and pesticides. In Senegal, for example, the introduction of certain leguminous species (moringa or faidherbia albida) has helped to fix nitrogen, improve soil health and reduce the need to purchase nitrogen-based fertiliser⁸.

Innovation also offers opportunities. With sensors to measure soil moisture and plant hydration levels, plant observation platforms, and artificial intelligence techniques, a range of tools are being fine-tuned around the world to assess and deploy more effective approaches to water management⁹.

Cities: the drinking water challenge

Another major issue directly related to climate change is people’s access to water. The WHO estimates that every individual requires 50 litres of water a day to meet their basic needs¹⁰. Receiving that amount is far from the norm, as an estimated 2 billion people are at risk of water stress in 2022. With almost 70% of the world’s population expected to live in urban areas by 2050, including 1.3 billion Africans, the challenge is to ensure that cities have access to water. According to the World Resources Institute (WRI)¹¹, 17 countries, including Saudi Arabia, India, Iran and Pakistan, are already under “extreme water stress” due to low freshwater reserves, poor water management and unusable groundwater in times of drought. In recent years, the depletion of water resources has also threatened heavily populated megacities such as São Paulo in Brazil and Chennai in India.

One of the most critical situations has arisen in Cape Town, South Africa. After three years of almost no rainfall, the city’s freshwater reserves fell below 30% due to a combination of climate change and poor water management. The city authorities made it clear to people that ‘Day Zero’ – when tap water would be unavailable – was likely to occur a year later.

A massive effort has been made to ensure reliable access to water for all the city’s residents. Pricing policies, regulations and awareness campaigns, especially for communities in informal settlements, have been introduced to provide access to water and to encourage the responsible use of supplies. An effort was also made to improve the use of rainwater storage, while also clarifying the responsibilities of each public authority involved and improving cooperation between city services.

Shanghai, Mexico City, Los Angeles, Manila, Jakarta, Istanbul… the world’s major urban centres have all been working to reduce the risks of water shortages for several years now. Cairo, for example, relies on solidarity between different parts of the country in the form of transfers between water basins via canals. A longstanding solution for improving the management of reserves is to build dams, so that reservoir water can be provided for a desired location when necessary. Although the financial – and ecological – cost of dam construction is particularly high, they have the advantage of being able to produce carbon-free energy.

Other possibilities include the sustainable use of groundwater (as in Sao Paulo or New York) or the desalination of seawater. The French Institute for International Relations (IFRI) estimates that 21,000 desalination plants are operating worldwide, a figure that has doubled since 2012¹². This option is favoured by Gulf States, where it provides 90% of Kuwait’s water and 70% of Saudi Arabia’s. Although desalination capacity is expected to double by 2030, the region is far from alone in using this technology, with countries in Africa, North America and South America launching similar projects. However, the process is not without its drawbacks: it is very energy-intensive and emits large quantities of greenhouse gases. Another issue is the management of brine, as the salt particles separated from seawater are returned to the ocean, causing saline levels there to rise.

From an economic and environmental point of view, there is clearly no ideal solution. However, faced with the scale of the challenge, all experts agree on one point: when it comes to water management, the first step is for governments, companies and the general public to be sensible in their use of resources. As part of this approach, every individual needs to be made aware – through training if necessary – of the benefits and vital importance of responsible water consumption.

Notes —
1. Source: the EU climate information service, Copernicus.
2. https://www.lesechos.fr/monde/europe/climat-lete-2022-est-le-plus-chaud-jamais-enregistre-en-europe-1786691
3. https://www.numerama.com/sciences/745366-5-milliards-dhumains-pourraient-ne-pas-avoir-un-acces-correct-a-leau-dici-2050.html
4. https://www.nationalgeographic.com/environment/article/himalaya-mountain-climate-change-report
5. https://www.geo.fr/environnement/triplement-des-pertes-de-recoltes-liees-aux-secheresses-en-europe-en-50-ans-204282
6. https://www.lemonde.fr/planete/article/2022/10/17/l-agriculture-chinoise-au-defi-du-rechauffement-climatique_6146074_3244.html
7. https://www.cirad.fr/espace-presse/communiques-de-presse/2022/l-agriculture-innove-pour-faire-face-au-manque-d-eau
8. https://theconversation.com/au-senegal-la-grande-caravane-de-lagroecologie-reprend-la-route-176575
9. https://theconversation.com/face-a-la-secheresse-innover-pour-transformer-notre-agriculture-187324
10. https://unesdoc.unesco.org/ark:/48223/pf0000367276
11. https://www.wri.org/news/release-updated-global-water-risk-atlas-reveals-top-water-stressed-countries-and-states
12. https://www.ifri.org/fr/publications/etudes-de-lifri/geopolitique-dessalement-deau-de-mer