The Environmental Protection Agency is looking to roll back the endangerment finding: its own landmark ruling which determines that greenhouse gas emissions could threaten public health and welfare under the Clean Air Act.
This decision legally obligates the EPA to regulate greenhouse gases under the Clean Air Act and became the foundation for broader climate change policy in 2009 when it was passed under the Obama administration. Earlier this summer, the Trump Administration announced its proposal to rescind all greenhouse gas regulations that have stemmed from it as a way to reinstate consumer choice.
Kathy Jacobs is the director of the Center for Climate Adaptation Science and Solutions at the University of Arizona and former director of the National Climate Assessment during the Obama administration.
She said the ruling is the legal basis for greenhouse gas regulation that has developed over the last 15 years or so.
"It's on that basis that there have been regulations for vehicle emissions, power plants and oil and gas production," Jacobs said.
Due to the fact that greenhouse gases have the effect of raising temperatures and increasing risks associated with climate impacts, Jacobs said there won't be ways to protect people against the impacts of climate change without that guidance.
"For Arizonans what that means is increased fire risk, increased drought, increased health related impacts, certainly heat," Jacobs said. "Each part of the United States has its own separate list of climate related impacts whether it's sea level rise or it has to do with changing climates and floods and droughts, it's a whole array of different things."
If the endangerment finding is rescinded, the EPA stated all greenhouse gas standards for light, medium and heavy duty vehicles and engines would be repealed.
This could affect the City of Tucson's goals to reach net-zero greenhouse gas emissions by 2030 under its Tucson Climate Action and Adaptation Plan.
Jacobs noted that people would have less incentive to reach net-zero emissions if regulations are rolled back.
"There won't be the regulatory limits and probably many of the fiscal incentives will be removed as well so it will be harder for the City of Tucson to meet its own goals and for others in the state as well," she said.