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By 2050, the world’s population is expected to reach 9.8 billion people, up from 7.6 billion in 2017. By the same year, demand for water will rise by one-third, straining a resource that already fails to provide clean, safe drinking water to more than 2 billion people.

A new report from the United Nations Educational, Scientific and Cultural Organization (UNESCO), “The United Nations World Water Development Report 2018: Nature-Based Solutions for Water,” suggests that world governments need to “work with nature, instead of against it” if humans want to “offset the rising challenges to water security from population growth and climate change.”

UNESCO Director-General Audrey Azoulay comments:

The stakes are high. Current trends suggest that around two thirds of forests and wetlands have been lost or degraded since the beginning of the 20th century. Soil is eroding and deteriorating in quality. Since the 1990s, water pollution has worsened in almost all rivers in Africa, Asia and Latin America.

The report calls for a reexamination nature-based solutions (NBS) to improve water management. The expanded application of NBS (primarily involving improved soil, vegetation and landscape management) to existing rain-fed crop systems, for example, offers projected gains equivalent to about 50% of current crop production from irrigation. This change translates to an improvement equal to 35% of current total water withdrawals worldwide.

NBS programs are also central to sustaining livelihoods in dryland areas and combating desertification using methods to rehabilitate land productivity.

Regarding the effects of climate change the UNESCO report notes:

The key impacts of climate change on humans are mediated through water … and occur mainly through climate-induced water-related shifts in ecosystems …. This implies that the key means for adapting to climate change is through ecosystem-based adaptation that improves the resilience of ecosystems to these climate-induced water-related shifts – that is, deploying NBS.

While the report does not put an overall price tag on NBS, it does provide estimates of global GDP under three scenarios. In the first, called the “regional rivalry” scenario, global GDP in 2100 peaks at $220 trillion. A “middle-of-the-road” (business as usual) scenario generates total GDP of $570 trillion by 2100.

Using a sustainability scenario, the report reckons that global GDP will reach $650 trillion by 2100, a level “consistent with contemporary conclusions that environmental sustainability is not a constraint to social and economic development, but a requirement to achieve it.”

The full report is available on the UNESCO website.