Heat-related deaths for older adults could increase by 370% through mid-century if climate warms 2 degrees Celsius

Annual heat-related deaths worldwide for people over 65 are projected to increase by 370% through the middle of the century if global temperatures rise by 2 degrees Celsius, a new report says.

The projection comes as heat-related deaths of adults over 65 have increased by 85% since the 1990s, according to the annual Lancet Countdown on Health and Climate Change report.

The hottest global temperatures in over 100,000 years were recorded in 2023 with the planet currently at 1.14°C of global heating, the report says.

Increasing global temperatures are linked to environmental changes like melting Arctic ice caps, drought and heat waves, and more intense hurricanes and wildfires. These stark changes are more than just ecological concerns; they also significantly impact human health, the report stressed.

This new Lancet report comes the same day as the new White House climate report, which flagged that climate-related hazards such as extreme heat, drought, and wildfires will continue to grow and directly impact human health.

There were on average 86 days of health-threatening high temperatures in 2018-2022, according to the Lancet report. Human-caused climate change made more than 60% of those days more likely to have happened, the analysis showed.

"We're already seeing climate change claiming lives or livelihoods in every part of the world. The impacts are happening here and now," said Marina Romanello, the executive director of the Lancet Countdown and a climate change and health researcher at University College London, during a press briefing.

Droughts and heatwaves are increasing globally, leading to food insecurity and water scarcity, according to the researchers. There has been a 29% increase in areas of extreme drought since the 1950s. Around 127 million more people said that they experienced significant food insecurity in 2021 than annually between 1981 and 2010.

The report also warned that warming ocean temperatures are enabling the spread of the Vibrio bacteria, which can cause serious illness and death if people swim in water with open wounds or eat raw or contaminated seafood.

The coastline area suitable for Vibrio bacteria around the world has increased every year by 329 square kilometers since 1982, putting around 1.4 billion more people at risk of diarrheal disease, severe wound infections and sepsis by 2022.

"Climate breakdown has begun, and humanity is staring down the barrel of an intolerable future. We are already seeing a human catastrophe unfolding with the health and livelihoods of billions across the world endangered by record-breaking heat, crop-failing droughts, rising levels of hunger, growing infectious disease outbreaks, and deadly storms and floods," said United Nations Secretary-General António Guterres in response to the Lancet report.

The Paris Agreement, the international treaty on climate change, calls for the world to keep global warming to well below 2-degrees Celsius, with the aim of limiting the increase to 1.5-degrees Celsius.

The new report found that under the 2-degree warming scenario, there would be 525 million additional people experiencing significant food insecurity by 2031-2060. There would be 23–39% more cases of infection with Vibrio bacteria under the 2-degree warming scenario. There would also be a 37% increase in the spread of dengue, a mosquito-borne illness that can be life threatening, the report says.

"Continued warming could lead to those patterns spiraling out of control," Romanello said to the projections outlined in the report.

The researchers behind the report say that there needs to be urgent action on climate change to mitigate the health impacts.

Khushali Jhaveri, MD, a board-certified internal medicine physician, is a hematology/oncology fellow at Moffitt Cancer Center and is a member of the ABC News Medical Unit.