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CLIMATE CHANGE IN ARIZONA

What a changing environment means for the state

By Ava Garcia

Climate change looks different in Arizona than it does in other states. There are no coasts to succumb to rising sea levels, no exacerbated hurricanes hurtling our way. At first glance, climate change in Arizona, for the most part, manifests as the mercury in the thermometer slowly inching up higher each summer. But there's much more happening in the state: plants and animal species are declining, vegetation is changing and drought is taking its toll.

 

Extreme heat is the norm in Arizona; triple-digit temperatures are a routine part of life in the summer. But because of this, Arizona serves as an intriguing case study of what happens when the extreme is pushed even further. The temperature increases in the Southwest are among the highest in the U.S.

 

Climate-change-inflated temperatures have more consequences than people having to crank up their air conditioners. Climate change is affecting a variety of facets of life in the state, from water availability to public health. Climate change is a global issue, but its consequences are felt locally.

 

The good news: There's still time to do something about this.

 

This five-part series will explore the various levels of action being taken in the state to prepare for climate change. The stories will examine these efforts through the lens of government action, business response, citizen movements and education of the next generation.

 

But first, read on to see what led to the climate change happening now and what impacts are expected to happen as a result in Arizona.

How did we get here?

Climate variations occur naturally over thousands of years, shaping the climatic conditions on Earth.

 

But what makes the climate change we face today so different from that of that past—and has raised alarm among scientists—is that the climate is changing at a much more rapid pace. It's also the first time the actions of a single species, humans, have had such a profound effect on the climate.

 

Since 1986, annual global average temperatures are much higher and have increased at a faster rate than any other 20-to-30 year time period in the last 1,700 years at least, according to the Fourth National Climate Assessment.

 

The reason for this accelerated pace? Much of it points to human activity, according the Fourth National Climate Assessment. The report, published in November 2018, states that "Many lines of evidence demonstrate that human activities...are primarily responsible for the climate changes observed in the industrial era, especially over the last six decades."

 

The main culprits are the emissions of heat-trapping greenhouse gases and land use changes, said Gregg Garfin, associate professor in the School of Natural Resources and the Environment at the University of Arizona. Garfin has been studying climate change since the late 1980s.

 

Greenhouse gases are an important component of our atmosphere. The sun sends energy to the Earth, which then reflects some of that heat back up to the atmosphere. While some of that energy escapes, greenhouse gases trap a portion of it in the atmosphere, keeping our planet warm. The problem arises when too much of these gases are in the atmosphere, trapping more heat and warming the planet.

 

"It would be uninhabitably cold if we didn't have those gases, but by putting more of those gases in, we've trapped more heat, and that's what's causing concern," Garfin said.

 

Land use changes, such as deforestation and development, exacerbate this problem. They alter the planet's ability to absorb heat-trapping gases in the land or ocean, Garfin said. For example, a forest can absorb carbon emissions by taking in carbon dioxide, but if the land is deforested to be turned into another development, that absorption capacity is taken away.

 

Increased heat can lead to a variety of problems across the globe. But how it affects each region depends on local characteristics.

Infographic by Ava Garcia.

Chart made in Google Sheets using data from the NOAA National Centers for Environmental Information.

What does climate change mean for Arizona?

Tree ring records in the Southwest indicate that the period since about 1950 has been warmer than any other time in the past 600 years, according to the 2013 report of the Assessment of Climate Change in the Southwest United States.

 

That heat has affected—and will continue to affect—many aspects of life in Arizona.

A map showing the change in temperature between the 1901-1960 average temperature and the 1986-2016 average temperature. Credit: from the Fourth National Climate Assessment Report, adapted from Vose et al. 2017.

On the most basic level, that means people, plants and animals will have to live through hotter days and nights. The decade between 2001 and 2010 saw the highest temperatures in the Southwest in the last century. The annual average temperature for the decade was 1.4 degrees Fahrenheit higher than that of the previous century, the 2013 report found. That trend could continue, as summer heat waves are predicted to become hotter and longer, according to the 2013 report.

 

Those inflated temperatures can create a feedback loop that exacerbates the problem of urban heat in Arizona cities, said David Sailor, the director of the Urban Climate Research Center at Arizona State University. Sailor has spent the last 25 years studying the urban heat island effect.

This effect explains the phenomenon of how urban spaces, unlike their rural counterparts, absorb and retain heat from the sun in paved surfaces during the day, leading to elevated nighttime temperatures long after the sun sets. A 2016 study found that areas in Phoenix that became more developed from 2000 to 2014 saw greater increases in temperature. In southeast Chandler, for example, night temperatures increased by 5.35 degrees Celsius, or 9.63 degrees Fahrenheit, during the study period.

 

As the temperature increases because of climate change, people will use more air conditioning to keep buildings comfortable, Sailor said. Powering those air-conditioning systems adds more heat—through emissions—into the environment, which then warms the urban environment more. People then use more air conditioning, creating a cycle, Sailor said.

 

Heat can be dangerous for human health. From 2006 to 2016, 1,193 people in Arizona died from heat exposure, according to a 2018 report by the Arizona Department of Health Services. Heat-related emergency department visits increased more than 22 percent—from 2,423 in 2015 to 2,957 in 2017, according to the ADHS.

Phoenix's Annual Temperature Records

2014 was Phoenix's hottest year on record, clocking an average temperature of 77.1 degrees Fahrenheit.

All but one of Phoenix's 10 hottest years on record have been since 2000.

Five of Phoenix's 10 hottest years on record have been since 2010.

Elevated temperatures can affect Arizona in other ways as well.

 

Higher temperatures decrease the longevity of snowpack, which is an important source of water for the Colorado River, Garfin said. The 2013 Assessment of Climate Change in the Southwest United States report predicts late-season snowpack in the mountains of the Southwest will continue decreasing because of the higher temperatures. With less snowpack lasting longer on the mountaintops, there will be less water to replenish reservoirs.

 

"For the same amount of snow that might fall on the ground, we're getting less bang for the buck in terms of the amount of water that comes out of the snowpack and gets into the reservoirs," Garfin said. "That's where the reliability of surface water supplies is a major concern for water managers throughout the western United States."

 

The 2013 report predicts continued declines in river flows, as well as more severe, hotter and frequent droughts, which could lead to increased water deficits.

The state's large supply of groundwater means that Arizona's water management isn't in crisis, said Katharine Jacobs, director of the University of Arizona's Center for Climate Adaptation Science and Solutions. She acknowledges that the change in the Colorado River is dramatic, though.

 

Jacobs, who was a water manager for 25 years, said some urban? parts of the state have a sophisticated water management system and don't face the same risk as  rural areas, which may have more basic systems.

 

Jacobs said declines in water flow also hurt the animals and plants that depend on the river for their habitat, harming ecosystems there.

 

Ecosystem disruption from climate change is a concern for Arizona forests, too. Warmer temperatures could also affect the breeding seasons of certain insect pests, which could in turn result in declines in vegetation. Garfin points to the widespread mortality of conifer forests on the Colorado Plateau as an example of this already happening.

 

An altered breeding season for insects like mosquitos also spells trouble for public health. A longer breeding season means a longer period of exposure to their bites, which could affect people's health if those mosquitoes carry diseases, Garfin said.

 

Climate change won't affect everyone the same way. When looking at the issue of climate change, Jacobs said, it's important to first examine the underlying vulnerabilities already present in the community, such as economic inequities. She is especially interested in monitoring the effects of climate change on tribal nations in Arizona, which she said face climate change-related impacts like reduced water availability, vegetation loss and changes in availability of traditional plants and foods.

 

There are documented disparities in how extreme conditions affect other groups as well. The elderly, people without access to air conditioning, infants, Native Americans, Latino and Hispanic Americans, African Americans and people with low incomes face higher rates of heat stress than the general population, according to the March 2015 Arizona Extreme Weather, Climate and Health Profile Report from ASU and the Arizona Department of Health Services. A 2012 study analyzed areas in metropolitan Phoenix that were more vulnerable to heat stress and found that Hispanics make up the largest proportion of residents in those vulnerable areas. These disparities could be amplified by elevated temperatures.

 

All may not be lost, though. Garfin, who worked on the 2013 Southwest report, said there are a variety of ways to respond to climate change.

 

"These are ongoing concerns, and they are very much in the mind of people managing our forests, water and public health," Garfin said.

How can we prepare?

To avoid the greatest catastrophes, the 2018 Intergovernmental Panel on Climate Change report recommends limiting global temperature warming to 1.5 degrees Celsius (or 2.7 degrees Fahrenheit) overall. To reach that goal, the report calls for decreasing global carbon dioxide emissions by 45 percent below 2010 emission levels by the year 2030.

 

But 1.5 degrees Celsius worldwide doesn't mean an equal distribution of temperature. Places on dry land or near the Poles will experience greater warming than 1.5 degrees Celsius, said Diana Liverman, a University of Arizona professor in the School of Geography and Development who also worked on the IPCC report.

 

Because of that unequal distribution of heat, Liverman said she and many of her UA colleagues are focused on climate adaptation.

 

"One could argue that in Arizona, we know a lot about how to live in a warmer climate," Liverman said. "It's just when do we reach the limits to the adaptation?"

 

Adaptation is one of two main types of action in response to climate change. It means adapting to the changes that are happening as a result of climate change, such as implementing cooling features [like added shade from trees along sidewalks to deal with increasing temperatures.

 

The other type of action is mitigation. Mitigation entails taking action to decrease activities that contribute to climate change. This could mean cutting down on carbon-polluting activities, like riding a bike instead of driving a car.

 

"There's a cheap saying that mitigation is what you do for the world and adaptations are more local kinds of measures where you can really see the effect in your community," Garfin said.

"There's a cheap saying that mitigation is what you do for the world and adaptations are more local kinds of measures where you can really see the effect in your community," Garfin said.

 

In Arizona, people are working on both methods of action in response to climate change. These actions range from the large-scale—water managers looking at conservation measures—to the smaller, more personal level, like neighborhood groups working together to prepare for climate emergencies in their community in Tucson.

 

Garfin points to water conservation management as an example of an adaptation success story. As population has gone up in Arizona, per capita water use has gone down, Garfin said. That could be chalked up to conservation-savvy trends, like real estate developers and homeowners planting native vegetation instead of lawns to cut down on residential water use, Garfin said.

Types of Climate Action

Mitigation: Cutting down on behaviors that contribute to climate change.

Adaptation: Adapting to effects that are already happening in order to best live in the changing environment

"Real estate developers are probably not doing this waving the banner of climate change, but nonetheless this adaptation is helping us to conserve water," Garfin said.

 

When it comes to heat, increased energy efficiency can help mitigate the amount of carbon dioxide emitted, cutting down on contributions to climate change. An added bonus: Energy-efficient cities can help cool urban environments by reducing the feedback loop that contributes to the urban heat island effect, Sailor said.

 

Sailor pointed out other strategies to reduce urban heat, such as installing lighter-colored pavement and roofs to reflect sunlight away from surfaces.

 

Adapting can also mean taking note of how increased temperatures can affect people in their daily lives. Jacobs said it's important to establish networks of people to monitor each other's health, especially for people who may live alone or not have enough money to pay for air conditioning.

 

"That's where the vulnerability really comes in, people who can't pay for the kinds of adaptations that the rest of us take for granted," Jacobs said.

 

To even out those inequalities in adaptation, urban design can be a cheap way to protect residents from warmer temperatures, Liverman said. She said planting trees can help shade areas and keep them cooler, and putting shades on the outside of houses can help cool them down as well. 

 

Garfin said we're just scratching the surface of adaptation strategies that respond to climate change.

 

"I think some of these things are already happening, but we're at the frontier," he said. "We haven't really tapped anywhere near the degree we can, and we need to do it."

 

Jacobs said she still has an optimistic outlook on climate change because she knows there are solutions, but she thinks much of the future boils down to leadership.

 

"I think the thing that frustrates me more than anything is the fact that there are solutions, but our leaders and our population have not yet gotten ready to pay for them and implement them," Jacobs said.

 

She cites fear as a reason for hesitation on climate action, saying that some people think the solutions are more difficult than the problem.

 

Even if larger organizations aren't tackling climate change, people can still take action as individuals, both in adaptation and mitigation.

A 2017 study found that going car-free for a year in the U.S. could cut a person's personal carbon dioxide emissions by over 6,500 pounds.

Jacobs said people can limit their carbon emissions by looking at the transportation they use, how they heat their homes. and what they eat. One 2017 study found that going car-free for a year in the U.S. could cut a person's personal carbon dioxide emissions by more than 6,500 pounds.

 

Jacobs said people can also manage the effects of climate change in their lives by reducing water use—anywhere from taking shorter showers to installing water-efficient appliances—and incorporating water harvesting into their yards. Jacobs herself has an electric car, and she has solar panels, water harvesting, and a drought-tolerant landscape at her home.

 

To help communities know what to do about climate change, Jacobs and a group of scientists and local government experts from around the country recently formed a network and launched a report based on the National Climate Assessments to give people and local governments better access to scientific information they can use to make decisions in their own communities.

 

The network, called the Science for Climate Action Network (SCAN), seeks to establish a "network of networks," Jacobs said, to connect people who want to work together to solve climate problems. Those people range from local government officials in New York City to professors from Columbia University to leaders of environmental organizations.

 

SCAN's report calls for more collaboration between local and national efforts on mitigation and adaptation and for better use of scientific observations from citizens in their own communities to improve understanding of how climate change affects local areas. The report seeks to increase collaboration to work together on initiatives to prepare for a changing climate.

 

"I'm a big believer in the power of networks to achieve things," Jacobs said.