Marie McKenzie - Academia.edu (original) (raw)

Papers by Marie McKenzie

Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–... more Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–6. Although numerous studies report increased mortality associated with extreme heat events 1–7 , quantifying the global risk of heat-related mortality remains challenging due to a lack of comparable data on heat-related deaths 2–5. Here we conducted a global analysis of documented lethal heat events to identify the climatic conditions associated with human death and then quantified the current and projected occurrence of such deadly climatic conditions worldwide. We reviewed papers published between 1980 and 2014, and found 783 cases of excess human mortality associated with heat from 164 cities in 36 countries. Based on the climatic conditions of those lethal heat events, we identified a global threshold beyond which daily mean surface air temperature and relative humidity become deadly. Around 30% of the world's population is currently exposed to climatic conditions exceeding this deadly threshold for at least 20 days a year. By 2100, this percentage is projected to increase to ∼48% under a scenario with drastic reductions of greenhouse gas emissions and ∼74% under a scenario of growing emissions. An increasing threat to human life from excess heat now seems almost inevitable, but will be greatly aggravated if greenhouse gases are not considerably reduced. Sporadic heat events, lasting days to weeks, are often related to increased human mortality 1,2 , raising serious concerns for human health given ongoing climate change 1–3,8–16. Unfortunately, a number of challenges have hampered global assessments of the risk of heat-related death. First, heat illness (that is, severe exceedance of the optimum body core temperature) is often underdiagnosed because exposure to extreme heat often results in the dysfunction of multiple organs, which can lead to misdiagnosis 2,3,5,17. Second, mortality data from heat exposure are sparse and have not been analysed in a consistent manner. Here we conducted a global survey of peer-reviewed studies on heat-related mortality to identify the location and timing of past events that caused heat-related deaths. We used climatic data during those events to identify the conditions most likely to result in human death and then quantified the current and projected occurrence of such deadly climatic conditions. Hereafter, we use 'lethal' when referring to climatic conditions during documented cases of excess mortality and 'deadly' when referring to climatic conditions that are projected to cause death. We make this distinction to acknowledge that climatic conditions which have killed people in the past are obviously capable of causing death, but whether or not they result in human mortality in the future could be affected by adaptation. We do not quantify human deaths per se because the extent of human mortality will be considerably modified by social adaptation (for example,

Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–... more Climate change can increase the risk of conditions that exceed human thermoregulatory capacity 1–6. Although numerous studies report increased mortality associated with extreme heat events 1–7 , quantifying the global risk of heat-related mortality remains challenging due to a lack of comparable data on heat-related deaths 2–5. Here we conducted a global analysis of documented lethal heat events to identify the climatic conditions associated with human death and then quantified the current and projected occurrence of such deadly climatic conditions worldwide. We reviewed papers published between 1980 and 2014, and found 783 cases of excess human mortality associated with heat from 164 cities in 36 countries. Based on the climatic conditions of those lethal heat events, we identified a global threshold beyond which daily mean surface air temperature and relative humidity become deadly. Around 30% of the world's population is currently exposed to climatic conditions exceeding this deadly threshold for at least 20 days a year. By 2100, this percentage is projected to increase to ∼48% under a scenario with drastic reductions of greenhouse gas emissions and ∼74% under a scenario of growing emissions. An increasing threat to human life from excess heat now seems almost inevitable, but will be greatly aggravated if greenhouse gases are not considerably reduced. Sporadic heat events, lasting days to weeks, are often related to increased human mortality 1,2 , raising serious concerns for human health given ongoing climate change 1–3,8–16. Unfortunately, a number of challenges have hampered global assessments of the risk of heat-related death. First, heat illness (that is, severe exceedance of the optimum body core temperature) is often underdiagnosed because exposure to extreme heat often results in the dysfunction of multiple organs, which can lead to misdiagnosis 2,3,5,17. Second, mortality data from heat exposure are sparse and have not been analysed in a consistent manner. Here we conducted a global survey of peer-reviewed studies on heat-related mortality to identify the location and timing of past events that caused heat-related deaths. We used climatic data during those events to identify the conditions most likely to result in human death and then quantified the current and projected occurrence of such deadly climatic conditions. Hereafter, we use 'lethal' when referring to climatic conditions during documented cases of excess mortality and 'deadly' when referring to climatic conditions that are projected to cause death. We make this distinction to acknowledge that climatic conditions which have killed people in the past are obviously capable of causing death, but whether or not they result in human mortality in the future could be affected by adaptation. We do not quantify human deaths per se because the extent of human mortality will be considerably modified by social adaptation (for example,