Part 3: Warming climate endangers Arizona

Urban planners say green spaces such as Civic Space Park in downtown Phoenix can help mitigate the effects of warming temperatures in Arizona’s cities. (Cronkite News Service Photo by Grant Martin)

By GRANT MARTIN
Cronkite News Service

(This concludes the Cronkite News Service special report on the impact of a warming climate on the state of Arizona.  To read the first two parts, click on FOREST at the right and scroll down.)

It’s the year 2100.

A nine-mile paved loop in the Sonoran Desert outside Tucson is the only evidence of Saguaro National Park, which was shut down after its last surviving cactus was finally suffocated by an invasive grass.

In Flagstaff, chairlifts transport skiers above barren mountainsides, while the formerly individual trails below having been forced into an indistinct snowy expanse by a recent fire that wiped out thousands of acres of forest.

Millions of families in Phoenix and Tucson drink desalinated ocean water routed in canals from Mexico and California, a costly but necessary means of compensating for decades of drought that had drained the supply previously provided by the Colorado River.

These are just a few of the possibilities that experts from around the state offered when Cronkite News asked them how Arizona’s forests, deserts and major metropolitan areas might look at the end of the century given generally accepted rates of global warming.

Experts interviewed for this project based the possible outcomes on a projected increase in average annual temperature of 6 degrees Fahrenheit by the end of the century.

While each offered a different perspective and prediction for the future, all of the scientists interviewed agreed that Arizona must adapt quickly and with sensitivity toward an uncertain future.

Arizona without saguaros? Drought, plant invaders pose threats

Rising temps threaten water supply, air quality

PHOENIX – In the mid-20th century, this city experienced a population boom as people moved here from across the country, seeking the health benefits to be derived from a mild climate and low pollen count. Over the next century, however, a confluence of factors – each tied to climate change – threaten this quality of life.

From the summit of nearby Camelback Mountain, one can often see a thick blanket of smog enveloping the downtown area. As the temperature rises over the next century, experts say, the air quality will deteriorate even further, potentially causing serious health problems for many area residents.

Anthony Brazel, a climatologist at Arizona State University’s School of Geographical Sciences and Urban Planning, offers a dire forecast for the region’s air quality.

“There are already a number of studies worrying about livability and air quality,” Brazel said, “and as it gets hotter it’ll exacerbate ozone problems and ultraviolet radiation, especially during the summer months.”

Brazel has conducted extensive research on the “urban heat island” phenomenon, which suggests that Phoenix will heat at an even faster rate than its surroundings over the next century.

“Buildings, cement, asphalt, those sorts of infrastructure parts absorb a fair amount of heat during the day and release it at night,” Brazel said. “Already, since the middle of the 20th century, nighttime temperatures during the summer months here have risen by about 10 degrees Fahrenheit.”

Such temperatures will place an even higher premium on air conditioning in homes, driving up energy costs. Low-income residents may not have the resources to maintain a reasonable quality of life within their homes.

The heat island effect may be mitigated by a variety of measures, such as providing for more shade, reflective surfaces on buildings, thermally efficient construction materials and naturally green expanses such as parks.

But those steps could be moot in the face of an impending crisis of water availability.

A recent study by University of Arizona scientists Jonathan Overpeck and Bradley Udall projects that the average annual flow of the Colorado is projected to decrease by as much as 20 percent by 2050.

Even with conservation and re-use of its existing water supply, Arizona may be forced to rely on desalinated ocean water, requiring a canal construction project unprecedented in scale or expense.

Without sufficient water or cooling mechanisms, millions could conceivably leave cities like Phoenix and Tucson for more habitable climes.

“If it becomes too hot here, what happens if there’s a heat wave?,” asked Darren Ruddell, a researcher at Arizona State University’s Global Institute of Sustainability.

“Lots of people are going to die, lots of people are going to become sick and frankly a lot of people are going to leave,” he said. “And so we need to design cities more efficiently to reduce human vulnerability to climate change and heat stress.”

Ruddell asserts that water conservation is a critical means of ensuring the future viability of Arizona’s cities.

“Right now, about 65 percent of Phoenix’s residential water use is for outdoor purposes,” he said. “That’s our irrigation, that’s our pools, that’s our lawns, and that’s the kind of wastefulness that will need to be addressed in the future.”

Already, the cities of Mesa and Tempe are offering $500 subsidies to homeowners who convert their yards from grass to turf or gravel.

Though Ruddell remains unconvinced that the program will be viable in the long term – he believes the cooling effect of natural grass is more vital than the benefits of water conservation – the measures suggest that the issue of water scarcity is already on local city planners’ minds.

It’s also important for architects to take such considerations into account when designing new buildings in Arizona’s urban areas, according to Harvey Bryan, a sustainability scientist at ASU’s School of Architecture.

“No one knows how to use glass these days,” said Bryan. “Sure, it looks pretty, but it can be incredibly wasteful.”

Because of the amount of light and heat that glass lets into a building, it drives up energy costs associated with cooling the interior at a rate that may not be sustainable.

According to Bryan, architects should incorporate such methods by incorporating more vegetation along building exteriors, painting rooftops to better reflect heat instead of absorbing it and designing larger rooms to allow for better circulation of air.

As Phoenix adapts to accommodate each of these recommendations and considerations into its infrastructure and architecture, the view in 90 years from Camelback Mountain will likely reveal a city far better adapted to the challenges and social responsibilities brought about by climate change.