Water Management for Worst-Case Climate Change

The foundations of civilization–agriculture, urban life, and industry–are threatened by water scarcity. The necessary adaptations are extreme, and their implementation will cause significant social, economic, and political upheaval. But without radical changes, billions will face severe water shortages, famine, mass migration, and conflict.

Desalination: A Costly Necessity

As freshwater sources dwindle and become increasingly unreliable, many coastal regions will have no choice but to turn to large-scale desalination. This process, while energy-intensive and environmentally problematic, may become the only option for providing water to millions[i].

Consider the case of Perth, Australia, which has already turned to desalination as a major water source. By 2022, half of Perth’s water supply came from desalination plants powered by renewable energy[ii]. This may be a glimpse into the future of many coastal cities worldwide.

To implement this strategy, we must:

Invest heavily in renewable energy-powered desalination plants. Solar and wind energy can help offset the enormous energy demands of desalination.
Develop more efficient desalination technologies to reduce energy consumption and environmental impact. Promising technologies include forward osmosis and membrane distillation[iii].
Create extensive distribution networks to transport desalinated water inland. This will require massive infrastructure projects, potentially rivaling the scale of ancient Roman aqueducts.

The brine byproduct from desalination can devastate marine ecosystems if not properly managed[iv]. We’ll need to develop strategies for brine management, such as using it for mineral extraction or carefully dispersing it to minimize environmental impact.

Water Recycling: Overcoming Attitudes

In a water-scarce world, we can no longer afford to use water once and discard it. Advanced water recycling systems, including direct potable reuse, will become essential in urban areas[v]. This means treating wastewater to potable standards and reintroducing it directly into the water supply.

Singapore’s NEWater project provides a successful case study. By 2022, NEWater met up to 40% of Singapore’s water demand, with plans to increase this to 55% by 2060[vi]. The project has overcome public skepticism through rigorous quality controls and public education campaigns.

Key actions for implementing water recycling include:

City-wide water recycling systems, treating wastewater to potable standards. This will require significant upgrades to existing water treatment infrastructure.
Developing decentralized water treatment systems. This could include systems that recycle greywater for non-potable uses within individual buildings.
Overcoming resistance through public education campaigns. Help people understand that recycled water is often cleaner than conventional water sources.

Drinking treated wastewater will soon be a necessity for survival in many regions. We must start preparing the public for this reality now.

Farming with Less Water

Agriculture accounts for 70% of global freshwater use. In a 5°C warmer world, current farming practices must change to reduce water consumption while still feeding a growing population[vii].

Israel’s agricultural sector provides a model for water-efficient farming. Through drip irrigation, water recycling, and drought-resistant crops, Israel has increased its agricultural output sevenfold while maintaining the same water consumption[viii].

Essential changes for agricultural systems include:

Widespread adoption of drought-resistant crops and precision agriculture techniques[ix]. This includes using sensors and AI to optimize irrigation, applying water only where and when it is needed.
Implementation of deficit irrigation strategies, deliberately under-irrigating crops at specific growth stages to maximize water use efficiency.
Transition to vertical farming and hydroponic systems in urban areas. These systems can use up to 95% less water than traditional farming methods[x].
Development of salt-tolerant crop varieties for use with lower-quality water. This could allow us to use brackish water or even diluted seawater for irrigation.

These changes will be disruptive and may lead to significant shifts in global food production patterns, potentially exacerbating geopolitical tensions. Early planning for these transitions will minimize disruptions to food security.

Draconian Conservation: Every Drop Counts

In a world of extreme water scarcity, wasteful water use will become criminalized. Strict conservation measures and pricing structures can discourage excessive consumption[xi].

During Cape Town’s “Day Zero” water crisis in 2018, the city implemented severe water restrictions, limiting residents to 50 liters per person per day. This drastic measure, combined with other interventions, helped the city avoid running out of water[xii].

Potential measures for extreme water conservation include:

Tiered water pricing with punitive rates for high consumption. This could include exponentially increasing rates for usage above basic needs.
Mandatory water-efficient fixtures and appliances in all buildings. This might extend to requiring waterless toilets or greywater recycling systems in new constructions.
Bans on water-intensive landscaping and non-essential water uses. This could include prohibitions on private swimming pools, car washing, and ornamental water features.
Real-time water use monitoring and automated cutoffs for excessive use. Smart water meters could alert authorities to excessive use and even automatically restrict supply.

These measures will be deeply unpopular and may lead to social unrest, but they will be necessary for survival. We must start preparing the public for these possibilities and developing the legal frameworks to implement them when necessary.

Integrated Watershed Management

We can no longer afford to manage water resources in isolation. Integrated water resource management across entire watersheds will be crucial for maximizing available water and minimizing conflicts[xiii].

The Murray-Darling Basin in Australia provides both positive lessons and cautionary tales in watershed management. The basin-wide approach has improved water use efficiency but competing interests and climate change continue to pose significant challenges[xiv].

Key strategies for integrated watershed management include:

Implementing transboundary water sharing agreements. This will be crucial for preventing conflicts over shared water resources.
Developing comprehensive watershed-scale monitoring and modeling systems. This will allow for more accurate predictions of water availability and informed decision-making.
Restoring and protecting wetlands and other natural water storage systems. These ecosystems can help regulate water flow and improve water quality.
Managing groundwater as a strategic resource, severely limiting extraction. Where possible, we must treat aquifers as emergency reserves rather than primary water sources. Where aquifers are the primary water resource, use must not exceed recharge. Demands on many aquifers already exceed recharge. Further population growth, development, and even existing uses may have to be pared back.

However, we must also prepare for the likelihood that some aquifers and watersheds will dry up, leading to migrations and conflicts. The Colorado River Basin in the United States, which supplies water to 40 million people, is already facing this possibility[xv].

Atmospheric Water Harvesting

In the most water-stressed regions, we may need to turn to emerging technologies like atmospheric water harvesting. While currently inefficient, necessity may drive rapid advancements in this field[xvi].

The company Zero Mass Water has developed solar-powered panels that extract water from air, even in arid environments. While currently only able to produce small amounts of water, this technology could be a lifeline in areas where no other water sources are available[xvii].

Potential developments in atmospheric water harvesting include:

Large-scale atmospheric water harvesting farms in humid coastal areas. These could supplement traditional water sources in water-stressed regions.
Building-integrated systems in urban areas. Every building could become a small-scale water harvester.
Personal, portable water harvesting devices. These could provide emergency water supplies for individuals or small communities.

These technologies are not yet viable at scale, but in a 5°C warmer world, they may become essential for survival in some regions.

Water Management Conclusion

The water management challenge in a 4 or 5°C warmer world is unprecedented in human history. These adaptation measures—from energy-intensive desalination to draconian water restrictions—are extreme, and their implementation will cause significant social, economic, and political upheaval. But they may be the only hope for survival in a world transformed by runaway climate change.

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