WaterAid UK is a British organization dedicated to making “clean water, decent toilets and good hygiene normal for everyone, everywhere,” according to its website. In a recent report titled “Water and climate: Rising risks for urban populations,” WaterAid UK warns that “[w]ater emergencies are becoming more frequent and severe … Right now, 90% of natural disasters are water-related, and cities –– especially in low-income countries –– are on the frontlines.” The report’s findings “highlight the variability of climate change impacts across the globe and emphasize the heightened risks in highly populated cities with existing vulnerabilities.”
According to the United Nations, “55% of the world’s population lives in urban areas, a proportion that is expected to increase to 68% by 2050.” In North America, over 82% of the population lives in urban areas. This “gradual shift in residence of the human population from rural to urban areas” has picked up speed in recent decades, giving rise to so-called “megacities,” which the UN defines as cities with a population of 10 million or more. The intensification of climate instability is placing many of these urban residents at higher risk because “[o]ften, cities’ water supply, sanitation, and flood management infrastructure, and the systems that support them, were designed and developed when the impacts of climate change were less extreme and populations much smaller,” according to the report. “[A] mixture of political decisions, underinvestment and socio-historical factors, have created urban concentrations of deprivation where deep and intersecting social and infrastructural vulnerabilities are being exposed and exacerbated by intensifying climate hazards.”
Hazard events like droughts and floods are growing demonstrably more complex. The authors emphasize that the warming of the atmosphere means that it can hold more moisture. This phenomenon can have two distinct consequences. “First, a warmer atmosphere will tend to draw more moisture upward from land areas through evapotranspiration that may not be replaced by incoming precipitation.” This can make the land drier, “allowing anomalously warm and dry periods to become more intense, potentially leading to deeper droughts.” The second consequence of a warmer, more moisture-rich atmosphere involves an intensification of precipitation events such that “when precipitation does occur over a city, it may arrive in larger amounts for the same storm duration, potentially leading to increased flooding.”
“As the climate crisis throws the water cycle out of balance,” the report warns, “it is impacting many of the world’s largest cities in ways that are hard to anticipate and plan for.” Some cities “are experiencing dramatic climate reversals –– places used to heavy rainfall now face drought, while historically arid regions now grapple with unexpected floods.” But perhaps the most harrowing development described in the report is a phenomenon called “climate whiplash.” According to the authors, “Many communities ‘whiplash’ between droughts that dry up water sources followed closely by floods that overwhelm infrastructure, destroying toilets and sanitation systems and contaminating drinking water, with huge impacts on people’s health.” Fifteen percent of the cities examined in the report showed this trend, and the authors caution that “[t]hese whiplashing extremes in quick succession can be particularly hard for communities to prepare for and recover from.” Among the cities “experiencing an intensification of both wet and dry extremes,” Hangzhou, China, and Jakarta, Indonesia, as well as Dallas, Texas, topped the list.
While these sorts of studies often focus on cities (because that’s where the most people live), rural communities are also experiencing intensifying drought and precipitation cycles. The Independence Day weekend floods in the Texas Hill Country, following years of below-normal rainfall, are perhaps the clearest warning to date that climate-related events may be moving beyond our state’s ability to plan and prepare for them. Affected communities are not only grappling with the startling loss of life and the destruction of countless homes and businesses, but many of them are also under boil-water notices because the flooding has compromised their potable water systems.
In searching for solutions, the authors stress the need for “climate-resilient water, sanitation and hygiene … services that can withstand extreme climate hazards such as floods and droughts, backed by systems that can cope, adapt, transform and recover in the face of [the] shifting frequency and severity of these climatic events.” Infrastructure resiliency upgrades will play an essential role in climate adaptation, according to the report, with “an underestimated potential to contribute to climate mitigation and net zero emissions efforts, primarily through improved wastewater treatment and safe reuse.” The authors also tout the advantages of “green infrastructure” such as permeable surfaces, urban wetlands, and green roofs to “help absorb excess water during floods while also conserving water during dry periods” as well as “contextually-appropriate … rainwater harvesting and wastewater recycling” to mitigate “the effects of prolonged droughts.” More attention is also needed to ensure that “[s]anitation facilities and services … can withstand flooding and prevent spilling of human waste” to better protect public health.
“As the global water cycle changes throughout the world, often becoming less predictable and more extreme, climate-resilient water, sanitation and hygiene services and systems will be essential to the health and social stability of cities,” the authors write. We must understand that water is “the backbone of a healthy society … As governments and communities globally adjust to a new climate reality, change starts with water.”
Visit https://washmatters.wateraid.org/publications/rising-risks-urban-populations-water-climate-change to read the full report.Trey Gerfers serves as general manager of the Presidio County Underground Water Conservation District. A San Antonio native, he has lived in Marfa since 2013 and can be reached at tgerfers@pcuwcd.org.