Effect of Climate Change on Heat- and Cold-Related Mortality
Effect of Climate Change on Heat- and Cold-Related Mortality
Background High and low ambient temperatures are associated with increased mortality in temperate and subtropical climates. Temperature-related mortality patterns are expected to change throughout this century because of climate change.
Objectives We compared mortality associated with heat and cold in UK regions and Australian cities for current and projected climates and populations.
Methods Time-series regression analyses were carried out on daily mortality in relation to ambient temperatures for UK regions and Australian cities to estimate relative risk functions for heat and cold and variations in risk parameters by age. Excess deaths due to heat and cold were estimated for future climates.
Results In UK regions, cold-related mortality currently accounts for more than one order of magnitude more deaths than heat-related mortality (around 61 and 3 deaths per 100,000 population per year, respectively). In Australian cities, approximately 33 and 2 deaths per 100,000 population are associated every year with cold and heat, respectively. Although cold-related mortality is projected to decrease due to climate change to approximately 42 and 19 deaths per 100,000 population per year in UK regions and Australian cities, heat-related mortality is projected to increase to around 9 and 8 deaths per 100,000 population per year, respectively, by the 2080s, assuming no changes in susceptibility and structure of the population.
Conclusions Projected changes in climate are likely to lead to an increase in heat-related mortality in the United Kingdom and Australia over this century, but also to a decrease in cold-related deaths. Future temperature-related mortality will be amplified by aging populations. Health protection from hot weather will become increasingly necessary in both countries, while protection from cold weather will be still needed.
Scientific consensus indicates that anthropogenic climate change is likely to cause a range of direct and indirect effects on human health in developed and developing countries (Intergovernmental Panel on Climate Change 2014). These effects include an increase in heat-related mortality and morbidity in many parts of the world (Haines et al. 2006; McMichael et al. 2012). In the United Kingdom and Australia, annual and seasonal mean temperatures are generally projected to increase significantly over the 21st century, although these increases will not be geographically homogeneous [Australian Bureau of Meteorology (BoM) 2014; Jenkins et al. 2009]. The frequency of hot days (e.g., daily mean Central England Temperature > 20°C) has also substantially increased since 1900 and is likely to increase further in the future (Vardoulakis and Heaviside 2012). Similar temperature patterns have been observed in other regions in Europe and North America (Meehl and Tebaldi 2004).
Heat-related mortality is a matter of great public health concern, especially in the context of climate change (Huang et al. 2011). Climate change is expected to exacerbate the health impacts of heat through rising temperatures and higher frequency and severity of heat waves (Fischer and Schar 2010; Nitschke et al. 2011; Tong et al. 2010). Climate models also predict that extreme cold weather events are still likely to occur over European continental areas and other middle- and high-latitude regions under 21st-century warming scenarios (Kodra et al. 2011).
The magnitude of climate change–related impacts will vary substantially between countries and population groups. For example, the elderly are much more vulnerable to heat and cold than are younger age groups (Hajat et al. 2007, 2014). Heat- and cold-related health risks can also vary considerably across or within countries (Analitis et al. 2008; McMichael et al. 2008). Comparing health impacts in two or more countries, regions, or cities with different climatic or socioeconomic profiles can provide insights into risk factors (Gosling et al. 2009a; McMichael et al. 2008). There is evidence showing lower temperature thresholds for heat-related effects in "cooler" cities exhibiting lower mean summer temperatures than in "warmer" cities exhibiting higher temperatures (Gosling et al. 2009a). This suggests that populations can acclimatize and adapt to a warmer climate to some extent through physiological, spontaneous behavioral (e.g., wearing lighter clothes) and planned adaptation (e.g., thermal insulation, passive cooling, and ventilation in buildings, and planting of trees in cities) (O'Neill et al. 2009).
The scale and the pace of this adaptation are likely to depend on many location-specific parameters (e.g., built environment characteristics). Studies assessing future health impacts of climate change have often considered changes in mean temperature in the absence of any physiological, behavioral, or planned adaptation of the population to higher temperatures (Gosling et al. 2009a; Kinney et al. 2008). Currently, there is no standard method to account for the effect of acclimatization and adaptation to changing thermal conditions, which limits the predictive capacity of health impact assessment techniques (Hajat et al. 2014). A range of methods have been proposed for accounting for this effect, such as the analog cities (i.e., cities with different average temperatures but similar sociodemographic characteristics) and analog years (i.e., hottest years in past records) approaches (Gosling et al. 2009a; Huang et al. 2011; Kinney et al. 2008).
Although several studies have reported associations between ambient temperatures and mortality (Armstrong et al. 2011; Barnett et al. 2012; Basu 2009; Basu and Samet 2002; Gosling et al. 2009b; Hajat et al. 2007), there is less evidence on the likely future impacts of climate change on temperature related mortality (Christidis et al. 2010; Huang et al. 2011; Kinney et al. 2008). We have addressed this gap by estimating the direct effects of temperature exposure on public health in the United Kingdom and Australia over the 21st century. We modeled mortality impacts of current patterns of weather variability by region or city and age group, and applied these relationships to climate and population projections to estimate temperature-related health burdens in UK regions and large Australian cities during the 2020s, 2050s, and 2080s, under three emissions scenarios. Furthermore, we provided a systematic comparison of health burden estimates between the two countries and between age groups.
Abstract and Introduction
Abstract
Background High and low ambient temperatures are associated with increased mortality in temperate and subtropical climates. Temperature-related mortality patterns are expected to change throughout this century because of climate change.
Objectives We compared mortality associated with heat and cold in UK regions and Australian cities for current and projected climates and populations.
Methods Time-series regression analyses were carried out on daily mortality in relation to ambient temperatures for UK regions and Australian cities to estimate relative risk functions for heat and cold and variations in risk parameters by age. Excess deaths due to heat and cold were estimated for future climates.
Results In UK regions, cold-related mortality currently accounts for more than one order of magnitude more deaths than heat-related mortality (around 61 and 3 deaths per 100,000 population per year, respectively). In Australian cities, approximately 33 and 2 deaths per 100,000 population are associated every year with cold and heat, respectively. Although cold-related mortality is projected to decrease due to climate change to approximately 42 and 19 deaths per 100,000 population per year in UK regions and Australian cities, heat-related mortality is projected to increase to around 9 and 8 deaths per 100,000 population per year, respectively, by the 2080s, assuming no changes in susceptibility and structure of the population.
Conclusions Projected changes in climate are likely to lead to an increase in heat-related mortality in the United Kingdom and Australia over this century, but also to a decrease in cold-related deaths. Future temperature-related mortality will be amplified by aging populations. Health protection from hot weather will become increasingly necessary in both countries, while protection from cold weather will be still needed.
Introduction
Scientific consensus indicates that anthropogenic climate change is likely to cause a range of direct and indirect effects on human health in developed and developing countries (Intergovernmental Panel on Climate Change 2014). These effects include an increase in heat-related mortality and morbidity in many parts of the world (Haines et al. 2006; McMichael et al. 2012). In the United Kingdom and Australia, annual and seasonal mean temperatures are generally projected to increase significantly over the 21st century, although these increases will not be geographically homogeneous [Australian Bureau of Meteorology (BoM) 2014; Jenkins et al. 2009]. The frequency of hot days (e.g., daily mean Central England Temperature > 20°C) has also substantially increased since 1900 and is likely to increase further in the future (Vardoulakis and Heaviside 2012). Similar temperature patterns have been observed in other regions in Europe and North America (Meehl and Tebaldi 2004).
Heat-related mortality is a matter of great public health concern, especially in the context of climate change (Huang et al. 2011). Climate change is expected to exacerbate the health impacts of heat through rising temperatures and higher frequency and severity of heat waves (Fischer and Schar 2010; Nitschke et al. 2011; Tong et al. 2010). Climate models also predict that extreme cold weather events are still likely to occur over European continental areas and other middle- and high-latitude regions under 21st-century warming scenarios (Kodra et al. 2011).
The magnitude of climate change–related impacts will vary substantially between countries and population groups. For example, the elderly are much more vulnerable to heat and cold than are younger age groups (Hajat et al. 2007, 2014). Heat- and cold-related health risks can also vary considerably across or within countries (Analitis et al. 2008; McMichael et al. 2008). Comparing health impacts in two or more countries, regions, or cities with different climatic or socioeconomic profiles can provide insights into risk factors (Gosling et al. 2009a; McMichael et al. 2008). There is evidence showing lower temperature thresholds for heat-related effects in "cooler" cities exhibiting lower mean summer temperatures than in "warmer" cities exhibiting higher temperatures (Gosling et al. 2009a). This suggests that populations can acclimatize and adapt to a warmer climate to some extent through physiological, spontaneous behavioral (e.g., wearing lighter clothes) and planned adaptation (e.g., thermal insulation, passive cooling, and ventilation in buildings, and planting of trees in cities) (O'Neill et al. 2009).
The scale and the pace of this adaptation are likely to depend on many location-specific parameters (e.g., built environment characteristics). Studies assessing future health impacts of climate change have often considered changes in mean temperature in the absence of any physiological, behavioral, or planned adaptation of the population to higher temperatures (Gosling et al. 2009a; Kinney et al. 2008). Currently, there is no standard method to account for the effect of acclimatization and adaptation to changing thermal conditions, which limits the predictive capacity of health impact assessment techniques (Hajat et al. 2014). A range of methods have been proposed for accounting for this effect, such as the analog cities (i.e., cities with different average temperatures but similar sociodemographic characteristics) and analog years (i.e., hottest years in past records) approaches (Gosling et al. 2009a; Huang et al. 2011; Kinney et al. 2008).
Although several studies have reported associations between ambient temperatures and mortality (Armstrong et al. 2011; Barnett et al. 2012; Basu 2009; Basu and Samet 2002; Gosling et al. 2009b; Hajat et al. 2007), there is less evidence on the likely future impacts of climate change on temperature related mortality (Christidis et al. 2010; Huang et al. 2011; Kinney et al. 2008). We have addressed this gap by estimating the direct effects of temperature exposure on public health in the United Kingdom and Australia over the 21st century. We modeled mortality impacts of current patterns of weather variability by region or city and age group, and applied these relationships to climate and population projections to estimate temperature-related health burdens in UK regions and large Australian cities during the 2020s, 2050s, and 2080s, under three emissions scenarios. Furthermore, we provided a systematic comparison of health burden estimates between the two countries and between age groups.
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