By the time children born today are reaching their 80s, Flagstaff could see as many as 80 days per year with temperatures that climb above 90 degrees.
Currently, an average of just two days a year top 90 degrees.
And within that same time frame of the end of this century, Flagstaff could experience as few as 100 days per year when low temperatures drop below freezing.
That's half as many below-freezing days as the city currently averages.
The projections are part of Flagstaff’s new climate profile, released last week. Created by researchers at the University of Arizona, the profile summarizes Flagstaff’s historical climate data and makes predictions about future temperature and precipitation trends in the face of human-caused global warming.
It’s one of the building blocks for the city’s first Climate Action and Adaptation Plan, which will be released in draft form later this year, said Jenny Niemann, climate and energy specialist with the city of Flagstaff. By knowing what changes to expect in the future, the city can map out the areas and populations most vulnerable to those changes, such as hotter summers or lower-snow winters, Niemann said. That will help the city take a more targeted approach to adapting to and mitigating climate change impacts, she said.
“We want to make sure our actions and strategies respond to specific risks Flagstaff is facing,” she said.
The Flagstaff profile gives a range of future climate scenarios that correspond with different levels of carbon emissions. Right now the world is tracking on the highest-emission, worst-case scenario, said Alison Meadow, a Research Scientist with the University of Arizona’s Institute of the Environment who worked on the climate profile.
Staying on that track would mean that by 2100 Coconino County will be more than 10 degrees hotter than the current average. Under that scenario, average temperatures would be on par with those in Albuquerque by 2050 and those in Sierra Vista by 2100, the report said. Even under a low-emissions scenario, the county’s average temperature is projected to be almost 6 degrees higher than the current average by 2100.
Particularly detrimental to Flagstaff’s winter tourism industry is the fact that average low temperatures are rising much faster than high temperatures. That means more precipitation will fall as rain instead of snow throughout the year because there will be fewer days that dip below freezing, Meadow said.
The models predict little to no change in the total amount of precipitation the area receives annually. But hotter temperatures increase evaporation from surface water sources, soils and plants, which means an increased likelihood of conditions ripe for wildfire. Hotter summers could also mean Flagstaff residents will have to start thinking about air conditioning, Meadow said.
After working with several tribes, Flagstaff’s is the first city-specific climate profile produced by the University of Arizona’s Climate Assessment for the Southwest program, Meadow said. The idea is to provide data specific to each community so decisionmakers can better plan for the future, she said.
“It’s a big deal to have to think about changing your local economy because agriculture isn't going to work or snow is going to be less plentiful,” she said.
The climate profile’s analysis of past temperature and precipitation data from local weather stations shows temperatures in Coconino County have already been climbing.
Among the findings:
- In almost every year since 1985, average annual temperatures have been higher than the long-term average.
- 2017 was the warmest year on record for Coconino County.
- Eight of the last 10 years have seen longer-than-average growing seasons in Flagstaff.
- Between 1985 and 2016, Flagstaff has experienced fewer below-freezing days than in the time period from 1950 to 1985.
Shawn Newell, with the Citizens Climate Lobby, said the Flagstaff profile “brings the data home” and serves as a handy tool for groups like hers to show there is a problem and it’s happening here.
“It gives us all a common reference to use,” she said. “More information that is sound and reliable is helpful in telling the story people need to hear to be able to get ramped up to make a difference.”