A comprehensive new data analysis (Walkowiak et al., 2025) involving European countries finds it takes less than 18 years for humans to adapt to a 1°C increase in mean annual temperature. [emphasis, links added]
Consequently, exposure to excessive heat has become less deadly over time.
Supporting this conclusion, a 2018 study involving 305 locations across 10 countries (1985-2012) affirmed a “decrease in heat-mortality impacts over the past decades,” as “heat-related mortality [fractions, AFs] decreased in all countries.”

Many heatwave or excess heat mortality studies fail to account for the human capacity to adapt to extremely hot temperatures through the expansion of air conditioning access, heat-shielding structures, building materials, etc.
This (intentional?) failure artificially inflates modern heat exposure risks so as to make it appear heat wave mortality has become more and more of a problem.
The real risk is cold exposure.
Since the 1980s, humans have been 20 times more likely to die from exposure to excessively cold temperatures than to excessive heat.
So-called “green” policies that insist on adding heat pumps to homes (due to their lower dependence on fossil fuels) impose more risks to humans, as heat pumps notoriously cannot keep structures warm enough during cold spells.
As heating demand and costs rise, there will likely be more susceptibility to cold-related deaths in the future. In contrast, heatwave-related mortality will likely continue to decline.
Read more at No Tricks Zone