Climate Change Series: Pima County





By David A. Schaller

With Tucson as its county seat, Pima County has grown from a fairly sleepy desert town at the end of World War II to a major hub of government, academia and tourism. With a population now topping one million, the county’s eastern reaches reflect a sprawling landscape of urban development bounded by scenic mountain ranges, Native American reservations, and an expanse of desert lands where critical habitats and cultural resources are now protected from development by the award-winning Sonoran Desert Conservation Plan.

In a livable but occasionally unforgiving Sonoran Desert environment, Pima County has been continuously inhabited for over 4,000 years. For millennia, the Santa Cruz and Rillito rivers drained the surrounding watersheds and their flowing water allowed permanent habitation to flourish. Less than a century ago, that all began to change as continued growth dried Map_of_Arizona_highlighting_Pima_County.svgthe rivers and sent aquifer levels plunging from 30 feet to 300 feet. Population rise and unsustainable water practices soon made an alternative to ground water critical. The Central Arizona Project (CAP) entered the picture in the 1980s, bringing new water resources to the county and relieving stress on depleted aquifers.

Soon, climate change arrived with a fury as a 17-year drought and 18 straight years of above-normal temperatures parched urban and rural areas alike. While Tucson’s annual rainfall is frequently cited as being “about 12 inches,” over the last decade the National Weather Service shows the annual average to be 9.7 inches, almost 20 percent less than the historical average. Regional drought has raised the prospects of declining flows in the Colorado River; and with demand exceeding supply below Lake Mead, Tucson and Pima County will feel the first cutbacks of CAP water under future shortage scenarios.

Ultimately, all water users in the county will need to pay more if desert communities are to remain tolerable in the face of water shortages. University of Arizona law professor Robert Glennon, who serves as Water Policy Advisor to Pima County, notes that “quite simply, we are not paying the true cost of water” and that with rare exceptions the water itself is free. Well, almost. My own March 2017 Tucson Water bill totaled a mere $20.00 and included a consumption charge of but $4.65 for the 2,244 gallons used, a cost of $0.00207 per gallon (two-thousandth of a cent) – hardly a price signal to change behavior.

Meanwhile, spring arrives earlier each year and record high temperatures in Pima County are no longer reserved for the summer months nor measured in tenths of degrees. In March of this year, Tucson experienced an average temperature almost eight degrees above normal, making it the warmest March on record.

Notwithstanding the array of climate challenges faced across Pima County, its non-governmental, academic and community sectors remain arguably among the leaders in climate change action anywhere in Arizona. Regional organizations like the Sky Island Alliance and Watershed Management Group work on multiple fronts, from accelerating use of rain and stormwater collection to the development of new science to support climate change adaptation at a landscape level. Another bright spot in the county is the University of Arizona’s Institute of the Environment (IoE), a national center of excellence in climate change science and outreach.

One of the many successful climate adaptation efforts in the county includes work by the Tohono O’odham Tribe to divert some of its CAP allocation and help restore a small segment of the Santa Cruz River, reminding themselves and others what a living river and desert riparian ecosystem looks like. In the public sector, Pima County itself has developed a range of metric-driven goals for decreasing energy and water use and increasing the use of renewable energy. The IoE is helping the county quantify these climate and energy goals so it can mark implementation progress, report back to the public, and budget appropriately. Elsewhere, the County Health Department continues preparing to respond to the worst-case effects expected under future heat emergency scenarios.

Pima County is of course not alone among Arizona counties in needing a more aggressive response to the onset of climate change. To date, its efforts have been largely led sdcp-headerby the nonprofit and university sectors, neither of which has the ultimate muscle to force bold changes in public policy. Public sector responses are needed on a scale to match the urgency of risks faced, before the full force of climate change arrives.

For Green Living’s climate change series, each month we will focus on one of Arizona’s 15 counties and how climate change is affecting it specifically. Next month’s installment will focus on Pinal County.

David A. Schaller is a retired environmental scientist living in Tucson where he writes on climate, water and energy security.


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