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Climate experts say it is clear humans are influencing global climate change, and the Southwestern United States will feel the impact through rising temperatures.

The Intergovernmental Panel on Climate Change, an international organization of scientists investigating climate change, released the first part of its fifth assessment report last month. The report showed “human influence on the climate system is clear," according to an IPCC news release.

The forthcoming second part of assessment will examine the impacts, adaptation and vulnerability relating to climate change. That report is set to come out March, 2014.

As scientists and communities all over the world await the newest data on climate change, local government officials, scientists, physicians and community members gathered in Tucson to evaluate the public health impacts of climate change in the Southwest.

Climate change, though variable, is happening worldwide. But the Southwest desert, a region that includes Arizona, particularly feels the impacts of increasing temperatures. The reason for that is quite simple.

“It’s hot here already in the summer,” Tucson Mayor Jonathan Rothschild said. “And when the temperatures are too high, it’s dangerous for people outside and for people without adequate cooling.”

One of the authors of the fourth IPCC assessment report, Kristie Ebi, said that has consequences.

“There’s a lot of health outcomes, injuries, illnesses and deaths that are associated with weather and climate, or that are seasonal in some way,” Ebi said. “And any of those could be affected by climate change.”

Different regions are affected in different ways, she explained. For example, Pacific islands are more affected by sea level rises or storm surges. Such events can change “their ability to not only get to hospitals but their access to water, malnutrition and diarrheal diseases.”

Those are very different from the risks communities in the southwest are exposed to, Ebi said

Heat strokes, Diseases, Wildfires a Bigger Concern in AZ

The most apparent health impacts of climate change specific to Arizona are heat-related. The Tucson Fire Department responded to 153 heat-related dispatches from July 2012 to July 2013, according to Barrett Baker, the department's spokesman.

Some impacts of increasing temperatures are direct and obvious, such as heat strokes and dehydration. Others are rather subtle. For example, the rate that infectious pathogens multiply is dependent on temperature.

During hot summers, outbreaks of pathogenic diseases like diarrheal conditions can be observed, Ebi said. That’s because the bacteria inside the food we consume replicates faster in higher temperature, she said.

“When we get diarrheal diseases from eating these foods, it’s often dependent on how many organisms we ingested,” she said. “So, when it gets hotter, they replicate more and more and you ingest more when the food gets contaminated.”

Mosquito pathogens work in the same way: Mosquito bacteria also multiplies more quickly in higher temperature, said Heidi Brown, a University of Arizona public health professor who specializes in vector-born diseases.

“We’re concerned about whether or not there will be more increases in the vectors so that the probability of you getting hit by a mosquito increases because there are more of them out there and [whether it] survives long enough to transmit the virus,” Brown said.

Another health concern for Arizona and the Southwest is wildfires.

“We see this increasing expectation for wildfires,” Brown said. “There are risks to that, risks being things like smoke and inhalation of that, and then burns and injury.”

Determining the Vulnerability to Adapt to the Changing Climate

In order to adapt to the changing climate and mitigate the risks it will bring about, it is important to determine the “vulnerability” of a community or individual, said Leslie Ethan, the director of Tucson’s Office of Conservation and Sustainable Development.

Vulnerability has to do with something called “adaptive capacity,” which includes how young or old an individual may be, or whether a person has pre-existing conditions that may increase the degree of risks, she said. It also relates to the amount of resources an individual or a community has.

“It comes down to ‘it’s getting hotter, can you afford to run the air conditioner more?’ and unfortunately, that’s not a very good strategy,” Ethan said. “The better strategy is to make your house more energy-efficient so you don’t have to run the air conditioner more.”

Resources, such as money, can often determine how much people can “buffer” themselves from the impacts of climate change, she said.

Renovating homes to be energy-efficient is one strategy, but Ethan said, there are more affordable ways to mitigate health risks caused by climate change.

“The most cost-effective way to deal with heat is planting trees,” she said. “Green infrastructure.”

Tucson sponsors programs like Trees for Tucson, a program started by a local non-profit organization Tucson Clean & Beautiful. The organization provides desert-native home shade trees, such as the Mesquite, to Tucson Electric Power and Trico Electric Cooperatives at a low cost, Ethan said.

Ebi, the climate change consultant, said awareness about the potential risks is the key to adapting to climate change.

“[The important things are] understanding that heat is a risk and people do have to take action to protect themselves, making sure that that you look out for neighbors who may be at higher risks and making sure that they’re taking the kinds of actions that need to be taken,” she said.

More on climate change in the Southwest. Its impacts at the Roy P. Drachman Agua Caliente Regional Park, where natural springs are drying, creating a challenge for county officials who want to maintain the site as a recreation area on Tucson's northeast side.

Yoohyun Jung is a University of Arizona journalism student and apprentice at Arizona Public Media.