Impact of future cold and heat on mortality by two exposure measurements under different scenarios: Impact of global warming in the west of Iran

Satellite-based data has been currently considered as an important exposure in projection studies of climate change impact on mortality. We projected all-cause mortality attributable to heat and cold by 2099 under adaptation, population change and climate scenarios using the data, in addition to ground-based exposure. Air temperature was estimated using Land Surface Temperature (LST) in a city-specific regression model. The predicted temperature was corrected for the bias using Bland–Altman approach and observed data in each city. The bias-corrected and observed predictors were then used in a two-stage time series regression to estimate baseline city-specific and pooled associations across five cities. Combination of the dose–response association and projected temperature by RCPs and GCMs along mortality data were used in the projection analysis. The temperature was estimated to increase by 6 °C in all of the regions under the worst scenario. Based on station data and under all scenarios, the Attributable Fraction (AF) and number of deaths due to cold were higher than heat in all decades in future. Also, the uncertainty in the heat effect was low if there is no adaptation to heat especially during 2020–2050 (e.g., AF for the worst scenario of RCPs and population variant was 0.07 (Empirical CI: 0.01, 0.12)). However, both exposures showed an increasing impact (Attributable Fraction (AF) and number of deaths) of heat and decreasing impact of cold in future. Compared to station-based data, the uncertainty in heat impact using the predicted data was lower under all scenarios in all decades. Along the observed data measured by weather stations the satellite-based exposure should be addressed in the studies of the projection of climate change impact on mortality. Our findings specifically highlight the urgent need for adaptive strategies to mitigate the impacts of extreme heat events, particularly in the cities like Ilam where adaptation scenario had an important role on the projection analysis.