The cost of climate change: Will summer air conditioning use save lives or take them?

In the near future, climate change and the predicted warmer summers will take a heavy toll on air quality and health and researchers predict that the increased use of air conditioning in the buildings we work and live in will further degrade air quality and increase the burden of air pollution on our health. Results of this new study were published in a special climate change issue of Public Library of Science (PLOS) Medicine.

“Climate change is here, and we’re going to need to adapt. But air conditioning and the way we use energy is going to provide a feedback that will exacerbate air pollution as temperatures continue to get warmer,” said lead author David Abel, graduate student, University of Wisconsin-Madison Nelson Institute for Environmental Studies’ Center for Sustainability and the Global Environment, Madison, WI. “What we found is that air pollution will get worse. There are consequences for adapting to future climate change.”

For their analysis, Abel and colleagues combined projections from five different models to forecast increases in summer energy use in a warmer climate, and the effect of these increases on power consumption from fossil fuels, air quality, and health in a few decades. They simulated three scenarios, including present-day climate, midcentury climate with present-day emissions, and midcentury climate with emissions from adaptation.

With climate change, the frequency and intensity of heat waves are projected to increase during the summer. Air conditioning will save lives, but if the increased use of air conditioning depends on power from fossil fuels, it will cause deleterious effects on air quality and health, warned senior author, Jonathan Patz, MD, MPH, professor of environmental studies and population health sciences, University of Wisconsin-Madison.

“We’re trading problems,” said Dr. Patz. “Heat waves are increasing and increasing in intensity. We will have more cooling demand requiring more electricity. But if our nation continues to rely on coal-fired power plants for some of our electricity, each time we turn on the air conditioning we’ll be fouling the air, causing more sickness and even deaths.”

According to co-senior author Tracey Holloway, PhD, professor of environmental studies and atmospheric and oceanic sciences, University of Wisconsin-Madison, buildings are the largest energy sinks in the United States, accounting for more than 60% of the power usage in the eastern United States. Air conditioning makes up a significant portion of the electrical demand.

The study found that climate change alone could increase concentrations of fine particulate matter (PM_2.5) by 58.6% and ozone by 14.9% for the month of July by the middle of this century. When they compared present day to the combined impact of climate change and increased building energy use, PM_2.5 concentrations increased by 61.1%, and ozone concentrations by 15.9%. They concluded that 3.8% of the total increases in PM_2.5 and 6.7% those of the ozone will be due to the use of extra air conditioning to adapt to the escalating heat.

By the middle of this century in the eastern United States, they predicted an additional 13,547 deaths annually, at a cost of $126 billion, due to the higher summer levels of PM_2.5, and 3,514 deaths due to ozone, at a cost of $32.5 billion.

Their analysis and sobering findings highlight the need to develop more sustainable sources of energy, including wind and solar power, and more energy-efficient air conditioning units.

“The answer is clean energy,” concluded Abel. “That is something we can control that will help both climate change and future air pollution. If we change nothing, both are going to get worse.”

This study was supported by the National Institutes of Health, the George Bunn Wisconsin Distinguished Graduate Fellowship in Energy Analysis and Policy, and the Wesley and Ankie Foell Graduate Award in Energy Analysis and Policy.