Flagstaff could see up to a 40 percent decline in summertime monsoon precipitation if carbon dioxide emissions continue to rise across the globe.
The projection comes from a new study by a team of researchers from Princeton and the National Oceanic and Atmospheric Administration that modeled how rising surface and air temperatures caused by increasing emissions would affect the monsoon in the southwestern United States and northern Mexico.
A change in these summer rains has implications for water resources as well as water-related hazards like flooding across those regions, said Sarah Kapnick, a research physical scientist with NOAA and a co-author on the paper.
So what sort of impact could Flagstaff see if that projection plays out?
With winter snowmelt being the main recharge for local water supplies, the city’s water security may not see a huge hit with a decline in monsoon precipitation. But the story is different for elements like the region’s fire season, its ponderosa pine trees and other native plant species. For them, those summer rains play a major role.
“Plants in our area definitely respond to and are dependent on the monsoon, they are adapted to our climate and that’s what our climate does,” said Lynne Nemeth, executive director of the Arboretum at Flagstaff. “They bloom with the moisture from the monsoon and that’s when they are thriving.”
In overall numbers, the monsoon does provide a hefty proportion of Flagstaff’s precipitation. The city receives an average of 21.8 inches of moisture per year, with rainfall during monsoon season making up about 8.3 inches of that, or nearly 40 percent.
The summer rains help reduce fire danger across northern Arizona in the summer and, along with spring snow melt, are a crucial source of moisture for local vegetation.
“Decreasing that second precipitation event would likely have a strong impact on local vegetation,” said Kristin Haskins, director of research at the Arboretum.
When it comes to ponderosas, the monsoon has more of an indirect impact. According to research out of Northern Arizona University, medium to large-sized ponderosa pine trees around Flagstaff use almost none of the water that falls as rain during the summer.
“It may seem surprising that summer rain is not used, but it makes sense when you consider that most of the tree roots are below 20 cm depth, yet the summer rains wet only the soil surface (except in super heavy monsoon years),” George Koch, a biology professor at NAU wrote in an email. It was Koch’s doctoral student Lucy Kerhoulas, who completed the ponderosa pine research.
At the same time, Kerhoulas found a positive correlation between years with lots of summer rain and greater late-summer growth in ponderosas. Koch said they think that while the monsoon rains may not directly impact tree growth, they are accompanied by milder, more humid air that spurs the trees to ramp up photosynthesis.
The rainfall that comes from monsoon thunderstorms makes only a small contribution to groundwater recharge in this region, said Brad Hill, director of Flagstaff’s water services department. Much more groundwater recharge comes from snowmelt, though modeling shows that only 4 to 8 percent of total precipitation ultimately filters down into the local aquifer system, Hill said.
It’s also rare that summer rain will have any effect on the level of Upper Lake Mary, Hill said. In 2013, the monsoon brought such heavy rainfall that the lake rose by 11 percent in two weeks, but that was a big anomaly, he said.
Flagstaff citizens don’t appear to cut back on their water usage in response to the monsoon rains either, Hill said. Looking back over the past 10 years of data, there’s no strong correlation between a month of hefty rainfall and any lower water demand, he said.
“What we surmise is while people cut back when it rains, when the sun comes out they want more water,” Hill said.
The projected decrease in monsoon precipitation calculated by the Princeton and NOAA researchers has to do with the forces that cause the summertime thunderstorms to form. Instability in the atmosphere combined with moist air close to the surface is what creates those rain-bearing storms, said Salvatore Pascale, lead author on the paper. But rising surface temperatures have the effect of reducing moisture in air close to the surface and increasing atmospheric stability, which inhibits the updrafts that cause thunderstorms, Pascale said.
The eye-catching 40 percent decrease in precipitation that the study estimates is based on a scenario of carbon dioxide concentrations in the atmosphere doubling compared to 1990 levels of 350 parts per million.
Models show that such an increase isn’t unlikely.
In one scenario used by the Intergovernmental Panel on Climate Change, under which actions are taken by countries to reduce greenhouse gas emissions so they peak in 2040 then begin to decline, carbon dioxide concentrations would reach almost double 1990 levels by the end of this century.
Past studies have shown that global warming will cause the monsoon to shift later in the season, but Pascale said his study didn’t produce that finding. In his models, the impact wasn’t a delay in summer moisture, it was an overall drying out, he said. A future study will look at how global warming might impact the intensity of monsoon thunderstorms, Pascale said.
One study published in September by University of Arizona researchers analyzed historical data and found the intensity of monsoon precipitation is already increasing in some parts of Arizona. Shifts in the thermodynamic environment have been facilitating “stronger organized monsoon convection” for at least the past 20 years, the authors found.
The road to a new job started at Bushmaster Park for some young people at the launch event for StartHere, a job training program run by Coconino County to connect young job seekers with training and jobs.
Carol Curtis, the director of the county’s Career Center, said the plan is a new way to reach youth that would otherwise be “disconnected,” meaning they are not in school and do not have a job.
“They can be a very hard group to connect with,” Curtis said. “We are trying to reach them where they are.”
“Where they are” so far has meant places throughout Flagstaff, including the Bushmaster skate park, coffee shops, parks, recreation centers and just walking down the street, Curtis said.
Curtis said about 15 percent of people between 16 and 24 years of age are “disconnected,” and said the program’s “human centered design” could provide a better way of keeping people interested in the process.
The redesigned program and effort came after the county received $150,000 that was left over from Maricopa County’s allotment, and the county allocates $205,000 per year to continue to fund programs for young adults. With the additional funds, Curtis and her team created a marketing campaign that includes an outreach specialist connecting with youth around the county, a video marketing campaign to increase interest and the launch event to give young people a chance to meet with the leaders of the program, talk about their goals and have some pizza.
The county estimates spending about $10,000 per individual in the program each year, and expects people to stay in the program for several years, until they reach their goals, Curits said.
Once a person connects with the StartHere program, one of the staff will meet with them a few times to talk about the person’s interests and past work or school experience. The person can take assessments to see what career path might fit them best, and the Career Center can connect and fund trainings and certifications, Curtis said.
“We can pay for their trainings, like coding classes or other certifications,” she said.
The center will then help connect individuals with internships, which the county will pay for until the person can be hired by a company, she said.
Curtis said some of the individuals might be hesitant to open up about their own personal history, with the fear that it might hinder them from finding a job. But, disabilities, previous contact with law enforcement and teenage parenthood can make people eligible for other programs and services.
Nicholas Stone, one of the event attendees, said he is still in high school, but is interested in what the program could have to offer once he graduates. Stone makes his own stencils for paint, and said he would like to explore jobs that could involve his art.
“I’m really interested in helping the community and helping people,” he said.
Terrin Zee said he attended the event to look at options for a job.
“I wanted to look for a job, hopefully one that will lead to a career,” he said. He has experience in construction and said he would be interested in continuing to work in that field.
“I think this is really helpful,” he said. “This is a real resource for young adults, and helpful to get them where they want to be with some footsteps to follow along the way.”
For more information about the program, visit www.starthere.jobs
A tiered system that allows organizations to get a volume discount for buying reclaimed wastewater at off-peak hours could soon be eliminated to help raise money for capital improvements to the city’s reclaimed wastewater distribution system.
At the Flagstaff City Council meeting Tuesday night, city staff proposed a three-year adjustment period to increase prices for reclaimed wastewater in the city. For most customers, costs would increase about 7 percent per year for three years.
The plan also included a three-year phase-out of the tiered rate structure for “off peak” users, which means users that can store the water on their properties and can have water delivered at night. The tiered rate allows customers that buy more than 150 million off-peak gallons to buy subsequent gallons at a cheaper rate. City Water Services Director Brad Hill said only one customer in the city buys enough off-peak reclaimed wastewater to qualify for the second-tier price.
The increased revenue from the rate increases would be used to fund capital improvements to the program, which include six projects, two of which would rely on the increase for funding. The projects total about $5 million. The two that require a rate increase for funding are the replacement of a pipeline bottleneck that would double the supply of water into the reclaimed system from the Wildcat treatment plant and a second storage tank at Buffalo Park, Ryan Roberts, an engineering manager for the Water Services Division, told the council.
The goal of the increases is to eventually bring the reclaimed water rates to 35 percent of the cost of the potable water equivalent, Hill said. In 2002, the rate for reclaimed water was set to be 35 percent of the cost for potable, but in 2010 the council told city staff to decouple the rates, Hill said.
During the public comment period, Ward Davis, a member of the Flagstaff Water Group, called the increase structure “a good compromise” and said the only customer affected by the second tier of off-peak rates, Continental Country Club, might not even reach the threshold of the 150 million gallons three years from now, when the tier is eliminated.
Davis said many reclaimed wastewater customers might spend even less money on reclaimed wastewater in 2020 than they did in 2016 because they will be using less.
John Malin, who also addressed the council during public comment, said there is a benefit to the off-peak users, who are willing to buy water that would be discarded without them. Malin compared off-peak buying to a red-eye flight, and said there are costs associated with having to store water on site that make up for the discount the customers receive.
The rate increase proposed by city staff and approved by the city Water Commission contains a different increase percentage for peak time consumers and off-peak consumers. However, Vice Mayor Jamie Whelan and councilmembers Jim McCarthy, Celia Barotz and Eva Putzova asked that city staff also prepare a rate structure that included an increase that would keep the disparity between peak time users and off-peak users the same, instead of the staff’s plan, which would increase the price disparity.
Mayor Coral Evans said she would like city staff to research what the revenue difference would be if the council kept the disparity in prices for the different customers, and said changing the staff’s plan “might not be worth it” if the amount is “not enough to do a project and it’s going to cause issues.”
A public hearing on the proposed reclaimed wastewater rates will be held during the November 7 city council meeting.