A study published in Nature confirmed that 2023 was the hottest on record in the northern hemisphere in 2,000 years, and a separate study published in Nature Communications found that more than 200 million seniors will be living in areas of extreme heat by 2050.

Study details

For the first study, researchers calculated the difference between temperatures from last year and temperatures from preindustrial summers recorded between 1850 and 1900. They found that temperatures in 2023 were 2.07 degrees Celsius higher than they were during preindustrial times.

Then, the researchers looked at 2,000 years of tree ring widths, which can help estimate temperature, and found that 2023 was hotter than preindustrial times on average by 2.2 degrees Celsius.

Regardless of whether 2023 was hotter by 2.07 degrees or 2.2 degrees, "the reality didn't change," said Jan Esper, a professor of climatology at Johannes Gutenberg University and corresponding author of the paper.

"It's very, very concerning," Esper said. The record-breaking heat from 2023 is one step in a clear continuing trend. "I would not be surprised by another huge step in the next 15 to 20 years," Esper said.

In the second study, researchers looked at population data from the United Nations Population Division and publicized estimates of climate change predicting warming temperatures in the coming years.

They found that, by 2050, more than 23% of the world's population over the age of 69, or up to 246 million people, will be living in areas where peak temperatures hit above 99.5 degrees Fahrenheit, or 37.5 degrees Celsius.

"Everywhere around the world, we see increasing life expectancy, which is bringing many more older adults into the healthcare system due to climate change," said Giacomo Falchetta, a scientist at the Euro-Mediterranean Center on Climate Change in Italy and an author of the study.

"This is not a question of if, but when," Falchetta added. However, his research found that the intensity of exposure risk for the older population can be lowered if greenhouse gas emissions are brought down aggressively and countries develop effective plans to protect older people from heat.

Discussion

Heat kills hundreds of people in the United States every year, according to federal records, and those numbers are increasing. However, some experts believe those deaths may be undercounted. Heat can exacerbate other health conditions, which can make it difficult to know whether it is a contributing factor to an illness or death.

Research shows that heat can impact a person's cardiovascular health and their risk for chronic conditions, STAT reports. Other emerging research has found that heat can have an impact on mental health, dementia, Alzheimer's disease, addiction, sleep, and other conditions, according to Ashley Ward, director of the Heat Policy Innovation Hub at Duke University.

In addition, common medications like antipsychotics, beta blockers, diuretics, and others can affect how the body manages heat, making more people vulnerable.

"Many people do not realize how deadly extreme heat can be," said Jennifer Wang, executive director of the Yale Center on Climate Change and Health.

According to Ward, clinicians need more incentives to help track deaths and illnesses caused by extreme heat in the way they code patient conditions at the hospital. As it stands, only a few diagnosis codes like heat stroke are billable. Ward said that clinicians need to know how to document the impacts of heat on other diseases and be given enough time to do so.

Ward added that pharmacists can also help educate people about the risks of medications that can make a person more susceptible to high temperatures but emphasized that change needs to happen outside of the healthcare space too.

Local governments need to make policy changes like requiring more energy-efficient building codes or setting legal maximum temperatures for rented apartments, experts said.

According to Kai Chen, an environmental epidemiologist at Yale University, the first step to addressing climate change at the national and international level is recognizing the scale and urgency of the problem.

Demographic changes are already in motion and are basically unstoppable, Chen said. But how much heat older people are forced to experience can change, and for any climate action that happens now, the "benefits will be much larger in the future than today," he said. (Gaffney, STAT, 5/14; Park, TIME, 5/14; Borunda, NPR, 5/14)

2 ways health systems can help mitigate effects of climate change 

By Miles Cottier

There are two significant responsibilities health systems must recognize and address to mitigate the effects of climate change, including heat-related illness.

1. Create a robust response plan 

To effectively address heat-related illness in the communities they serve, health systems need to be resilient. They must adapt their service offerings to accommodate higher volumes of patients, especially those with cardiovascular conditions. Health systems must also ensure that they have a robust plan that allows them to respond quickly to the needs of the surrounding community on high-heat days. 

This typically involves partnering with actors they might not normally work with, and establishing and refining roles that enable high-risk patients to be treated quickly and transported to cooler environments. Since it will likely take time to fine-tune this process, health systems should seek partners and conduct simulation exercises as early as possible to identify and address inefficiencies.

2. Reduce contribution to climate change 

Health systems need to reduce their own contributions to climate change. For a long time, climate change has felt slow-moving, distant, and perhaps a problem that other places in the world would experience first. But it's clear that this is no longer the case. Climate change is here. It's happening. And it's the people in the community who suffer because of large-scale industry's inaction against it. 

Sustainability isn't just good for your patients. It's good for your business.

Focusing on "doom and gloom" rarely gets us anywhere, so let's look at what's in it for health systems. Environmentally sustainable business practice doesn't just help keep our communities healthy — it also brings wider benefits to organizations. It can help progress on the other things we care about — including cost control, growth, and attracting and retaining staff. More and more health systems across the United States are using environmental sustainability as a lever to make progress in these areas (and others), and it's working for them.

Making progress on something as enormous and complex as environmental sustainability requires leadership ownership and accountability. Leaving it all to a few passionate but junior members of staff is not going to be enough to move the needle to reap the rewards you seek, environmental or otherwise. 

Progress instead requires a coalition of the willing, fronted by leaders who offer powerful voices that engage the wider system and who make it part of their job to connect sustainability to their organization's mission and objectives. 

The sooner health system leaders take ownership of environmental sustainability, the easier and faster it will be for health systems to thrive in a world that's increasingly volatile for businesses and patients alike.

We will touch on all of this (and more) at our September summit "Pivots for a Sustainable Future," where you will learn from Advisory Board experts and peer organizations who are facing similar challenges.  (Sherman et al., PSNet, 1/4; Health Care Climate Council, Climate Action: A Playbook for Hospitals, 11/2023)

More Advisory Board resources on climate change

For more insights on how hospitals and health systems can respond to climate change, check out these Advisory Board resources:

• Bushfires, burnt homes, black skies—how one hospital helped staff emotionally recover from a climate disaster
• Climate disasters are coming for all of us. Here's how you can crowdsource innovations to build an effective response.
• Climate change is affecting heart health. Here's what you can do.
• 3 ways your climate change inaction will hurt your bottom line
• Why health systems should take action on climate change