Poor water management tends to exacerbate the impacts of climate change, not only on water resources but on society as a whole
Health effects, threat to biodiversity
Indeed, water quality will be affected by increased water temperatures and a decrease in dissolved oxygen, leading to a reduction in the self-purification capacity of freshwater basins. We will see increased risks of water pollution and pathogen contamination caused by floods or higher concentrations of pollutants during periods of drought. In addition to the impact on food production, the effects on physical and mental health – linked to disease, injury, financial loss and the displacement of people – are therefore likely to be considerable.
Many ecosystems, particularly forests and wetlands, are also under threat, reducing biodiversity. Water supplies will be affected, not only for agriculture – which accounts for 69% of freshwater withdrawals – but also for industry, energy production and even fisheries.
Areas most at risk: archipelagos, mountains, tropics and Far North
Much of the impact of climate change on water resources will be manifested in the tropics, where most developing countries are located, with potentially apocalyptic consequences for small island states, some of which could be wiped off the map. Mountainous areas are also exceptionally vulnerable through impacts on mountain glaciers and snowcaps, which show a decreasing trend almost everywhere in the world. The authors recognize, however, that a number of uncertainties remain, particularly at the local level and due to the seasonal variability of rainfall patterns.
Much of the impact of climate change on water resources will be manifested in the tropics
Suggested solutions: adaptation and mitigation
- Adaptation encompasses a combination of natural, technical and technological options, as well as social and institutional measures to mitigate damage and exploit the few positive consequences of climate change. It is likely to have very rapid benefits, mainly at the local level.
- Mitigation consists of the human actions needed to reduce greenhouse gases (GHGs) emissions while exploiting carbon sinks to reduce the amount of CO2 and other GHGs in the atmosphere. It can involve large geographical areas, but with gains that may spread over decades. However, the possibilities for mitigation in water management remain largely unrecognized.
Improved wastewater management
Wastewater treatment also contributes to climate change as it generates GHGs, accounting for an estimated 3% to 7% of all emissions. These emissions arise from both the energy required for wastewater treatment and the biochemical processes used. But because of the decomposition of the organic matter it contains, untreated wastewater is also a major source of methane, a powerful greenhouse gas. The report points out that wastewater harbours more energy than is needed for its treatment, provided, of course, that it is harnessed. It is estimated that worldwide, between 80% and 90% of wastewater is discharged to the environment without any form of treatment.
Wastewater treatment also contributes to climate change as it generates GHGs, accounting for an estimated 3% to 7% of all emissions
In concrete terms, the optimal management of water resources means investing in modern treatment techniques that allow for the extraction of methane from organic matter and then use this biogas to generate the energy needed to run the process, as is already done in waterscarce countries such as Jordan, Mexico, Peru and Thailand. These techniques have enabled
the public utilities concerned to reduce emissions by thousands of tonnes of CO2, while making financial savings and improving the quality of the service.
Unfortunately, note the authors, while the need to combat climate change through better management of the water cycle is well recognized, it is not being translated into reality. “The word 'water' rarely appears in international climate agreements,” observes Audrey Azoulay. The ‘nationally determined contributions’ submitted by States under the Paris Agreement remain general in nature, without proposing specific plans for water. While a majority of countries recognize water in their 'portfolio of actions', few of them have actually calculated the costs of these actions and even fewer have put forward specific projects. Meanwhile, the possibilities for synergies between adaptation and mitigation measures are often neglected.
Accessing climate funds
Water resources management and water supply and sanitation services are underfunded and require greater attention from States