Study shows cold kills more Americans each year

Even as the climate warms, the cold becomes a more deadly threat to Americans. New research this month shows that cold-related deaths have increased significantly in the U.S. over the past two decades.

Harvard Medical School researchers conducted the study, which aimed to better count deaths caused by cold temperatures in the US. They found that the country’s cold-related death rate has doubled since the late 1990s, with deaths especially rising in recent years. Important risk factors for the increase in deaths likely include extreme weather events linked to climate change, homelessness and social isolation, the researchers say.

Extreme temperatures at either end of the thermometer can be life-threatening. While recent research has shown that heat-related deaths have increased in recent decades, cold weather tends to be deadlier overall. A 2021 study finder that the cold was responsible for about three-quarters of global extreme temperature deaths in 2019, for example (there were an estimated 1.7 million deaths in total that year).

The Harvard researchers note that cold-related deaths in the US have only been minimally studied, and little is known about how this burden has changed over time. To address this knowledge gap, they analyzed death certificate data collected by the Centers for Disease Control and Prevention, focusing specifically on deaths in which cold was recorded as either an underlying cause or a contributing cause. .

Between 1999 and 2022, there were just over 40,000 cold-related deaths in the US, the researchers found. After adjusting for age, they found that the death rate rose from 0.44 cold-related deaths per 100,000 people in 1999 to 0.92 such deaths per 100,000 people in 2022. Much of that jump was the result of a significant annual increase in deaths between 2017 and 2022. The team’s findings were published this month in the journal JAMA.

“There has rightfully been an emphasis on heat-related deaths given the undeniable nature of global warming,” lead study author Rishi Wadhera, a cardiologist and public health researcher at Harvard, told Gizmodo in an email. “However, the results of our study serve as a striking reminder that cold-related deaths also remain an important public health problem.”

Although their study is not designed to identify any specific reason for this increase, Wadhera and colleagues highlight several possible factors.

Climate change is known to increase the risk of both warm and extreme cold weather eventsfor example. But it’s also likely that more Americans today are at greater risk of being left out in the cold than before, especially people with unstable living situations, Wadhera notes.

“For example, we know that the number of homeless people in the U.S. has increased over the past few years — this is a population that is most exposed to outdoor weather, including cold waves,” he said.

US homelessness levels have generally increased since 2016 (the early years of the covid-19 pandemic were a notable exceptionthanks in part to generous aid programs). In 2023, chronic homelessness OVER record numbers set in 2007, when modern data collection efforts began, according to the Department of Housing and Urban Development (their report for this year is yet to be released). Substance use and social isolation can also increase people’s risk of exposure to unsafe conditions, including temperature.

Certain trends emerged in the team’s data showing who was most vulnerable to cold-related deaths. Regionally, the death rate was highest in the Midwest, where winters can be particularly brutal, for example. The highest death rates among racial and ethnic groups were seen among Native Americans and black Americans, respectively, and the highest age-specific death rate was seen in people over 75 years of age.

The authors say more research needs to be done to reveal exactly why cold-related deaths have increased. At the same time, there are already steps that policymakers can and should take to prevent these tragic losses of life, such as ensuring that vulnerable populations live in homes with reliable indoor heating or expanding access to centers of heating.

“Our findings should raise awareness that injury and death from exposure to cold weather is possible — especially for older populations who have multiple health conditions, homeless people who are most exposed to the weather outside, and populations with low incomes who may not have access to an appropriate environment. indoor heating,” said Wadhera.