Executive summary
Climate change is reshaping the global water cycle, tightening supplies in many regions while increasing extremes of droughts and floods. At the same time, overextraction of groundwater is rapidly depleting aquifers, shifting fresh water from land to the oceans and accelerating sea level rise. Utilities and policymakers must plan for scarcer, more volatile water, while balancing energy use, environmental impacts, equity, and cross-border governance.[1][2]
What’s changing in the global water cycle
- Continental drying has accelerated since the mid‑2010s, driven largely by unregulated groundwater pumping. Drying regions across the mid‑latitudes are expanding and coalescing into "mega-drying" zones.[3]
- Groundwater depletion now contributes more to sea level rise than the melt from each of Greenland or Antarctica individually, indicating a large, ongoing transfer of fresh water to the oceans.[4]
- Agriculture accounts for roughly 70% of freshwater withdrawals globally, making farm water efficiency a dominant lever for resilience.[5]
The core challenges of water management under climate change
- Groundwater depletion and land subsidence
- Chronic overpumping in key basins (e.g., Central Valley, Ogallala) lowers water tables, increases pumping costs, and can irreversibly compact aquifers, reducing future storage capacity. Visible subsidence is widespread from Mexico City to parts of the U.S. and Asia.[6]
- Policy lag: Even where laws exist, long phase‑ins and partial geographic coverage allow depletion to continue.[7]
- Supply volatility and portfolio risk
- Greater variability in snowpack, runoff, and precipitation raises the value of reliable but costlier sources such as desalination, potable reuse, and demand-side conservation. San Diego’s Carlsbad plant now provides about 10% of regional supply at a premium, emphasizing reliability over cost.[8][9]
- Energy-water-climate tradeoffs
- Desalination and large-scale treatment consume significant energy. If powered by fossil electricity, they increase emissions and can create feedback loops that worsen aridity.[10]
- Environmental externalities
- Ocean-intake mortality, brine disposal impacts, and insufficient monitoring can harm marine ecosystems unless mitigated via subsurface intakes, diffusers, and strong permitting.[11]
- Governance and geopolitics
- Few countries have coherent national water strategies; transboundary basins lack robust frameworks, raising risks of conflict, weaponization of flow, and instability under scarcity.[12]
- Equity and affordability
- Rising costs for reliable supply risk burdening low‑income users and small growers. Policy must blend conservation incentives with protections for essential use and livelihood viability.
Strategic pillars for resilient water management
- Protect and replenish groundwater
- Establish enforceable sustainable yield caps with near‑term milestones; limit new wells in stressed basins; require metering and reporting.
- Expand managed aquifer recharge where hydrogeology permits, using flood flows, treated wastewater, and stormwater.