The paper, published in Nature Medicine, based findings on modelling estimates from data on 854 urban areas across 30 European countries.

The authors call for the implementation of more-stringent climate adaptation and mitigation strategies to prevent an increase in temperature-related mortality.

Understanding the balance between heat- and cold-related mortality is important as Europe faces rising temperatures. Previous studies have reported rates of 10 deaths by cold to every 1 death by heat in Europe, but climate change may shift this balance in the future, potentially decreasing the net deaths caused by temperature.

This raises concerns about increased heat-related mortality despite potential decreases in cold-related deaths. However, these studies did not consider changing demographic factors, which include ageing populations, and urban adaptations to increasing temperatures.

Pierre Masselot and colleagues analyzed temperature and mortality data to project future cold-, heat- and overall net temperature-related deaths in 854 European urban areas under different climate change, demographic, and adaptation scenarios from 2015–2099.

They calculate a net increase in temperature-related deaths (7.6 deaths per 100,000 people) in European cities by the year 2060, even under the highest sustainable development climate change-adaptation scenario the researchers analysed (SSP1-2.6). The authors attribute this to an increase in heat-related deaths that exceeds decreases in cold-related deaths.

Masselot and colleagues suggest that under the SSP3-7.0 scenario — in which carbon dioxide emissions double by 2100 — the cumulative death total will be 2,345,410 between 2015 and 2099. However, a reduction in risk by 50% due to climate adaptation measures under this same scenario could result in a projected total of 268,100 temperature-related deaths by 2100.

The authors note that these projections are based on certain assumptions that may have a high level of uncertainty, and that they did not consider specific drivers of adaptation or local climate characteristics, such as humidity, or consider rural areas in the analysis.