Comprehensive assessment of climate change risks
Authors: Jae Young Lee, Ho Kim
Journal: The Lancet Planetary Health (2017)

The world population faces various types of climate-related hazards, and both the frequency and intensity of hazards are projected to increase in the future because of climate change. Since climate change could increase human health risks, many previous studies1Li T Ban J Horton RM et al.Heat-related mortality projections for cardiovascular and respiratory disease under the changing climate in Beijing, China.Sci Rep. 2015; 5: 11441Crossref PubMed Scopus (46) Google Scholar, 2Kingsley SL Eliot MN Gold J Vanderslice RR Wellenius GA Current and projected heat-related morbidity and mortality in Rhode Island.Environ Health Persp. 2016; 124: 460-467PubMed Google Scholar, 3Schwartz JD Lee M Kinney PL et al.Projections of temperature-attributable premature deaths in 209 U.S. cities using a cluster-based Poisson approach.Environ Health. 2015; 14: 85Crossref PubMed Scopus (50) Google Scholar, 4Petkova EP Horton RM Bader DA Kinney PL Projected heat-related mortality in the U.S. urban northeast.Int Environ Res Public Health. 2013; 10: 6734-6747Crossref PubMed Scopus (47) Google Scholar, 5Murari KK Ghosh S Patwardhan A Daly E Salvi K Intensification of future severe heat waves in India and their effect on heat stress and mortality.Reg Environ Change. 2015; 15: 569-579Crossref Scopus (95) Google Scholar first estimated future temperatures or weather-related extreme events on the basis of global circulation models under climate scenarios, such as representative concentration pathways. Then, they projected the elevated future mortality caused by climate change on the basis of the relationship between temperature and mortality obtained from historical data. Additionally, population changes and adaptation scenarios were also considered to accurately address future health risks. Mortality changes linearly with total population.6Petkova EP Vink JK Horton RM et al.Towards more comprehensive projections of urban heat-related mortality: estimates for New York City under multiple population, adaptation, and climate scenarios.Environ Health Persp. 2017; 125: 47-55PubMed Google Scholar, 7Martinez GS Baccini M Ridder KD et al.Projected heat-related mortality under climate change in the metropolitan area of Skopje.BMC Public Health. 2016; 16: 407Crossref PubMed Scopus (22) Google Scholar, 8Wu J Zhou Y Gao Y Fu et al.Estimation and uncertainty analysis of impacts of future heat waves on mortality in the eastern United States.Environ Health Persp. 2014; 122: 10-16Crossref PubMed Scopus (10) Google Scholar Demographic composition changes in ageing countries can increase future mortality because of the increasing proportion of vulnerable elderly groups,9Lee JY Kim H Projection of future temperature-related mortality due to climate and demographic changes.Environ Int. 2016; 94: 489-494Crossref PubMed Scopus (56) Google Scholar, 10Li T Horton RM Bader DA et al.Aging will amplify the heat-related mortality risk under a changing climate: projection for the elderly in Beijing, China.Sci Rep. 2016; 6: 28161Crossref PubMed Scopus (66) Google Scholar whereas adaptation scenarios can compensate death burdens.6Petkova EP Vink JK Horton RM et al.Towards more comprehensive projections of urban heat-related mortality: estimates for New York City under multiple population, adaptation, and climate scenarios.Environ Health Persp. 2017; 125: 47-55PubMed Google Scholar, 10Li T Horton RM Bader DA et al.Aging will amplify the heat-related mortality risk under a changing climate: projection for the elderly in Beijing, China.Sci Rep. 2016; 6: 28161Crossref PubMed Scopus (66) Google Scholar Although projection of future mortality due to climate change has been actively studied during this decade, achievement of a comprehensive understanding of climate change risks is not yet close. This absence of understanding is partly because the heterogeneity in previous studies makes it hard to synthesise their results. Additionally, little research has been done into the integrated effects of various climate-related hazards. In The Lancet Planetary Health, Giovanni Forzieri and colleagues11Forzieri G Cescatti A e Silva FB Feyen L Increasing risk over time of weather-related hazards to the European population: a data-driven prognostic study.Lancet Planet Health. 2017; 1: e200-e208Summary Full Text Full Text PDF Scopus (149) Google Scholar present the future effects of the seven most harmful weather-related extreme events in Europe due to climate change. These seven events are heatwaves, cold waves, droughts, wildfires, river and coastal floods, and windstorms. They estimated the occurrence and intensity of the seven disasters as well as demographic changes in Europe until the year 2100 under business-as-usual climate and socioeconomic scenarios. Human vulnerability to extreme weather was obtained from disaster databases. This study has two strengths. First, it presents a comprehensive assessment of climate change risks by estimating the human cost from the seven most harmful extreme weather events, whereas previous studies mostly focused on projecting only the temperature-attributable mortality. Additionally, because of the consistency in study design, such as target population, location, and projection periods for each disaster, the effects of the disasters can be compared fairly with each other. Such fair comparison cannot be achieved from previous studies because of their heterogeneity. This comparison allows valuable information to be obtained to guide how mitigation efforts should be prioritised and focused. Second, this study also considered demographic changes in the projection of future human costs. Although most previous projection studies estimated the population on the scale of a nation or city, the authors incorporated a 1 ha-scale population projection, which is based on the dynamics of population and land use. Such fine-scale processing enables accurate estimation of population change in coastal flood-prone areas or of increases in city dwellers due to urbanisation. Forzieri and colleagues found that, first, two-thirds of the European population are expected to be exposed to weather-related disasters due to climate change annually by the year 2100, and disaster-attributable deaths are expected to increase by roughly 50 times. For the increased weather-related death toll, population change accounts for 10%, whereas climate change accounts for the remaining 90%. Second, among the seven disasters, heatwaves are the most lethal, accounting for 99% of the total future disaster-related mortality. Mortalities due to heatwaves are expected to increase by 5400%, due to coastal floods by 3780%, due to wildfires by 138%, due to river floods by 54%, and due to windstorms by 20%, whereas mortality due to cold waves is projected to decrease by 98%. The effects of heatwaves will be augmented by urbanisation (18% increase in city dwellers in Europe by 2050) and urban heat island effects. Similarly, the effects of coastal flooding will be amplified by population growth in coastal flood-prone areas (14% more than total population growth). In consulting the results presented in this study, readers should be aware of its assumptions. The study assumed that human vulnerability at baseline remains constant throughout the study period. People are known to adapt and become less vulnerable than previously to extreme weather conditions because of advances in medical technology, air conditioning, and thermal insulation in houses. Therefore, the results could be overestimated. Additionally, this study assumed that the effects of single hazards are independent, ignoring the combined effects, if any, of multihazard events. Despite its assumptions and limitations, the findings of the study will be useful for policy makers and urban planners to slow down climate change and mitigate its effects. We declare no competing interests. Increasing risk over time of weather-related hazards to the European population: a data-driven prognostic studyGlobal warming could result in rapidly rising costs of weather-related hazards to human beings in Europe unless adequate adaptation measures are taken. Our results could aid in prioritisation of regional investments to address the unequal burden of effects on human beings of weather-related hazards and differences in adaptation capacities. Full-Text PDF Open Access