Even one extra day of hot temperatures in a given month can increase public healthcare costs, according to a new analysis co-authored by an Oklahoma economist.
The analysis found that Medicaid spending, by ZIP code, increases by a quarter of a percent for every additional day that reaches 80 degrees, beyond what is typical for a given month. When a single day's temperature surpasses 100 degrees, Medicaid spending increases nearly 2%, researchers found.
The results were calculated using more than one million federal Medicaid records from 2019 through 2024 and years of temperature data, according to Travis Roach, a University of Central Oklahoma economics professor.
He said the study's findings may sound insignificant, but even a quarter of a percent could have big implications for a more than $900 billion program like Medicaid.
The analysis estimates that continued global warming could result in $2.1 billion to $2.7 billion in additional annual national Medicaid spending by 2050. It projects the cumulative cost increase from 2024 until then will be between $28 billion and $36 billion.
"If we have an especially hot year, the Medicaid bill that year will be higher than if it hadn't been that hot," he said. "I don't expect that our state government is currently planning on future warming trends, but they ought to."
Increased Medicaid costs on hot days are primarily driven by higher patient volumes, instead of more expensive claims, Roach said. Economically disadvantaged communities and areas with higher populations of children, racial minorities and older adults disproportionately accounted for the increase.
Anyone can suffer from a heat-related illness, but public health insurance programs, including Medicaid, are more likely to cover populations at higher risk from extreme heat, including low-income individuals, people with chronic illness and children. Medicaid recipients are also less likely to have access to residential cooling and are more likely to experience heat exposure at work.
Oklahoma was one of nine states that had more than 33 heat-related deaths in 2022, according to data from the U.S. Centers for Disease Control and Prevention. Climate projections indicate that extreme heat events will be more frequent and intense in coming decades, the federal agency reports. One analysis of federal climate data found that average annual temperatures in Oklahoma have increased 2.6 degrees since 1970.
Many existing studies explore the link between heat data and increased healthcare utilization, but Roach said he wanted to calculate the fiscal impact of warming temperatures.
"Everyone expects, when it's hotter, people have more health problems, so there's more spending," he said. "But we didn't have a number that we could attach to that."
Roach said he hopes the analysis' results further incentivize public health and environmental interventions.
"This research suggests that whether or not we actually say the words 'climate change,' these impacts are being felt," Roach said. "Whether or not we're willing to call this what it is, that doesn't change the fact that it will be showing up on the ledgers."
This report was produced by the Oklahoma Public Media Exchange, a collaboration of public media organizations. Help support collaborative journalism by donating at the link at the top of this webpage.
