| Background:In the context of global warming and climate change,it is speculated that cold spells will gradually decrease,but it is undeniable that climate change has increased the frequency and intensity of extreme weather events,and winter cold waves will continue to occur.The cold spells have huge impacts and threats to people’s health and life.Compared with heat waves,there has been less attention and related research on cold waves,and existing studies are still controversial or insufficient in terms of the definition of cold waves and the heterogeneity of population impacts.In particular,the understandings on the impacts of cold waves on the health of residents in China are very limited.Therefore,a comprehensive and systematic assessment of the impact of cold waves,as an extreme weather event,on the health of the population is of important public health significance.Objectives:(1)Based on historical temperature data collected by 791 meteorological stations in China from 1951 to 2018,to analyze the long-term trend and spatial characteristics of the cold wave in 31 provincial cities across China;(2)Based on the daily death data and meteorological data in 31 provincial capital cities during 2007-2013,to assess the impact of cold waves on population deaths,identify vulnerable groups,and determine the best definition of cold waves;explore the modification effects of characteristics of cold waves;(3)To project the excess mortality risk of the cold wave during the period from 2000 to 2100 in different climate change scenarios.Methods:(1)Change trend of cold waves:based on 6 descriptive trend indicators,we used the ArcGIS software to display spatial distribution,and applied Mann-Kendall test method to test long-term change trend;(2)Estimations oft he death impacts of cold spells:In a two-stage model strategy,we first fitted the Quasi-Poisson regression model to estimate the city-specific effect,then obtained the the pooled effect through a random effect meta-analysis model;Afterwards,we performed subgroup analysis according to the diseases,age group,gender,and education level,and test the significance of the subgroup difference;(3)Estimation and projection of death risks of future cold wave:The generalized Poisson model was used to estimate the baseline death risk,and the future temperature time series data obtained from the simulation of the global climate models(GCMs)was used to identify future cold waves.Finally,we estimated the excess deaths of future cold wave.Results:The characteristics(intensity,duration,and time of occurrence)of cold waves have certain geographical differences across the country.The frequency,intensity,and duration of cold waves in the north were higher than those in the south;The frequency,intensity and duration of historical cold waves decreased due to the global warming.Detailly,the occurrence times,total days,duration,single-day intensity,single-time intensity and total intensity of cold wave per decade decreased by 0.233 times(P≤0.001),0.915 days(P≤0.001),0.195 days(P=0.003),0.115℃(P≤0.001),0.719℃(P<0.001)and 2.413℃(P<0.001),respectively.The cold wave caused an increase in the mortality rate of residents(RR=1.55,95%CI:1.40-1.70),and respiratory and cardiovascular patients(RR=1.88,95%CI:1.65～2.11),the elderly(RR=1.62,95%CI:1.42-1.81),people with low education level(RR=1.63,95%CI:1.44～1.82)and southern residents(RR=1.76,95%CI:1.61～1.91)were detected as vulnerable groups.The mortality risks are positively correlated with the intensity and duration of cold waves,but negatively correlated with the time of occurrence;The health threat of the future cold waves will gradually decrease,and the higher the population growth rate,the higher the risk of death from the cold wave in the future;and the future mortality risks with the population adaption were higher than those without the people adaption;The SSP high emission scenario was significantly lower than the low emission scenario in the later period of the future;Taking the scenario with high population growth,SSP 4-8.5 carbon emissions,and the population adaption as an example,non-accidental excess deaths during 2081-2100 were 190(95%CI:99～293).Conclusion:The cold wave will pose a huge threat to the health of residents;The characteristics of cold waves will modify the health impacts of cold spells;More attention should be paid to protecting the vulnerable population;The threat of the cold wave to the health of the population is projected to be weakened in the future.The study can help formulate public health intervention policies to address climate change. |
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