Here’s why we can expect warmer, drier weather in Arizona

John Loleit has kept a watchful eye on the towering saguaros and well-worn trails of the McDowell Sonoran Preserve for 22 years.

Loleit, Scottsdale’s natural resources coordinator, travels almost daily into the wilderness of the 47-square-mile park in all weathers, repairing fences, leading hikes, and training park staff and volunteers.

READ ALSO: As the drought persists, here’s how Phoenix is ​​preparing

It encourages visitors to use their powers of observation to look for clues about what is happening in the environment around them from year to year.

“I tell people, pick a saguaro cactus, and it’s your saguaro. Every time you pass by, take a look. Look at the main vault,” Loleit said. “Over a period of time, do you see that he’s thin and his ribs are shrinking and losing water or opening up and getting bigger if it rains?”

Loleit has observed many changes to the reservation over the decades, especially regarding the impact of high summer temperatures on the Sonoran Desert. And the latest summary of climate data from the National Oceanic and Atmospheric Association predicts that Arizona’s climate will continue to warm, leading to higher temperatures, more intense wildfires and continued drought.

The city hired Loleit — who had a 25-year career with the National Park Service — to open Pinnacle Peak Park in north Scottsdale in 2000. He’s been an integral part of the McDowell Sonoran Preserve ever since.

Loleit knows the seasonal ups and downs of the reserve, but he has noticed changes. For example, more saguaro arms have fallen on the trails in recent years and more saguaros have been knocked over.

“Last summer, I was like, ‘Oh man, even the native plants, they’re stressed.’ You could see it,” Loleit said. “They had dropped a lot of leaves or the color had changed quite a bit. They didn’t look like happy campers.

Is this the result of stress related to climate change? Maybe, said Loleit.

“We’re in a 20-plus-year drought,” Loleit said. “It’s ironic when I hear people say, ‘Oh yeah, we’ve been through droughts before.’ If we look at the history of the Phoenix area from 800 to a thousand years ago, the Hohokam culture built huge canal systems all over this valley and were able to irrigate thousands of acres. But it still wasn’t enough and they had to leave.

“I just wonder if history will repeat itself at some point and if we have enough time to change.”

Loleit’s observations reflect the fact that Arizona’s average temperatures are increasing in tandem with global climate change.

NOAA’s National Environmental Information Centers released their 2022 State Climate Summaries for all 50 states in January.

The 2022 Arizona State Climate Summary report details the most recent temperature, precipitation, and climate data for the state from 2017 to 2020, in addition to historical data.

The report found that “temperatures in Arizona have increased by 2.5 degrees (Fahrenheit) since the beginning of the 20th century…(and) historically unprecedented increases in annual mean temperature are projected during this century.”

He also states that “the potential for more prolonged droughts in the future will pose a major challenge to Arizona’s environmental, agricultural and human systems. The risk of very large forest fires is expected to increase.

And the high variability of monsoon rainfall is also expected to continue.

The state climate summaries focus on the power of observation.

Arizona State climatologist and senior lecturer at Arizona State University, Erinanne Saffell, contributed data to the summary. It also publishes monthly state summaries on Arizona’s climate.

Climatology is about the statistical representation of climate history, Saffell said, and state summaries provide a critical perspective that helps us better understand what is happening now.

“They help us assess where we are, where we have been. And then from there, maybe we can connect to where we could go. Saffell said.

At first glance, the findings of the NOAA summary don’t seem so surprising: Over the past five years, Arizona has become hotter and drier, and these trends are expected to continue.
But there’s more to it, Saffell said.

“When we look at our current assessments, it tells us that we are seeing more of the same things. But we also need to understand that things change and at what level they change becomes important,” she said.
According to the 2022 summary, “The number of extremely hot days (in Arizona) has been above average since 1995, with the highest number occurring during the 2015-2020 period.”

2020 has been a particularly hot year, Saffell said, with the most days recorded over 110 degrees Fahrenheit in the past 50 years.

The NOAA summary also states that “the number of nights with a minimum temperature of 80°F or higher has been trending upward since 1995, also reaching an all-time high during the 2015 to 2020 period.”

Saffell and other experts are closely monitoring nighttime minimum temperature data.

“If we zoom in and look at what’s happening in our metropolitan areas, we can see that urbanization is producing a higher signature of climate change,” Saffell said. “The increase in temperatures in Phoenix over the past 50 or 60 years is much greater than the signature we see statewide.”

Urbanization is the conversion of natural surfaces, such as shrubs and sand, to harder surfaces, such as concrete and asphalt.

These urban surfaces absorb heat during the day and then re-emit it into the atmosphere at night, raising summer nighttime temperatures. This is called the urban heat island effect.

Extreme daytime temperatures make it harder for urban areas to cool down at night, increasing the likelihood of serious human health impacts, said David Hondula, who heads the new Office of Response and Mitigation. Phoenix heat.

Phoenix has seen a 430% increase in heat-related deaths since 2014, Hondula said during a Feb. 2 presentation to a city council subcommittee. A large percentage of those deaths are linked to the increase in the number of homeless people downtown, Hondula said.

“These people are on the front line of risk when it comes to summer heat,” he said. “Anything we can do to provide simple measures that can keep people cool, safe and alive this summer will be a high priority.”

The human body is extremely responsive to changes in heat, Hondula said, and people with heat-related illnesses are the real experts, feeling and observing the changes from year to year.

Understanding changes in precipitation is a little more complicated.

The 2022 summary stated that “the 2020 monsoon season was the driest on record, with just 1.5 inches of precipitation, well below the previous record”.

The summary also predicts that monsoon seasons in Arizona will continue to be highly variable. 2020, for example, was extremely dry, followed by 2021, which was one of the wettest years on record.

Saffell said this “boom or bust” monsoon cycle is typical of life in a desert.

“When we look at our summer rainfall, we recognize that some seasons will be wet, others will be dry,” Saffell said. “What we’re paying more attention to is what’s happening with our winter rainfall, because that’s really important to our water supply.”

The majority of Arizona’s water comes from groundwater that is recharged by winter precipitation, Saffell said.

Scientists are monitoring snow accumulation in the upper and lower Colorado River basins, which is essential for recharging groundwater sources, Saffell said.

Snow levels in the lower basin, which includes Arizona, are below average, although 2021 brought a fair amount of rain and snow, Saffell said.

But a wet event or a wet year doesn’t indicate a trend, Saffell said.

“It’s important to understand the scale we’re dealing with,” she said. “When we look at situations on a global scale, that’s not necessarily what we see when we zoom in on a state scale for precipitation. But what we see in Arizona is consistent with what we let’s see with global temperature changes over the last 100 years or so.

The continued temperature extremes and prolonged droughts in Arizona are also seen globally. NOAA recently reported that 2021 was the sixth hottest year on record for the globe since accurate and comprehensive records began in 1880.

Phoenix is ​​taking action to adapt and mitigate the effects of climate change. In October, the city council approved its updated climate action plan, which addresses changes to transportation systems, buildings and more that will reduce or limit greenhouse gas emissions.

It’s all part of the global effort to cut emissions to tackle global climate change, Hondula said.

“Efforts are being made locally to combat the warming effects associated with urbanization,” he said. “We are exploring what a cool roof program might look like and smart efforts are underway to think about reducing future temperature changes driven by urbanization. So there’s a lot going on at all levels in terms of long-term change.

Story by Fiona LQ Flaherty, Cronkite News

About Jefferey G. Cannon

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