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Uncertainties in Modeling Health Outcomes in Response to High Temperatures Sharon L. Harlan presented at the National Center for Atmospheric Research Uncertainties.

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Presentation on theme: "Uncertainties in Modeling Health Outcomes in Response to High Temperatures Sharon L. Harlan presented at the National Center for Atmospheric Research Uncertainties."— Presentation transcript:

1 Uncertainties in Modeling Health Outcomes in Response to High Temperatures Sharon L. Harlan presented at the National Center for Atmospheric Research Uncertainties in Climate Change Research Colloquium July 21 - August 6, 2014 GEO-0816168 BCS-1026865 1

2 Recent overviews and resources on climate change and human health and... Chapter 9 “Human Health” in the National Climate Assessment 2

3 A broad conceptual framework 3

4 Complex ecological networks disrupted by climate change 4

5 Climate sensitive disease at the urban scale Courtesy of Jeremy Hess Variability 5

6 Heat... The Silent Killer 2010 Moscow 11,000 dead 2003 Europe 70,000 dead 2010 Ahmedabad 1,344 dead India 1978 – 1999: 225 heat waves, uncounted deaths 6

7 Heat illness – human physiological response to high environmental temperature Direct Effects Mild: heat rash, heat edema, heat cramps Moderate: heat exhaustion (thirst, headache, weakness, fainting) Severe: heat stroke (nausea, increased heart rate, loss of consciousness) Indirect Effects Dehydration and consequences (e.g. renal) Cardiac atherosclerosis and stroke Congestive heart failure Respiratory diseases Diabetes 7

8 High confidence in more hot weather... On the other hand, casualties depend on many things CLIMATE CHANGE and EXTREME HEAT EVENTS 8

9 Scientific consensus on heat and health outcomes 1.The epidemiological signal of environmental heat (high temperature) on human health is clear. 2.Susceptibility to heat illness varies among different groups and some groups are more susceptible than others. 3.Social factors (e.g., isolation, occupation, access to AC, etc.) mediate heat risk. 4.Humans can acclimatize to higher environmental temperatures but there are physiological limits to survival. Workshop Participants, Urban Climate Institute, Georgia Institute of Technology, July 2014 9

10 Key scientific uncertainties about heat and health outcomes 1.What is the temperature ‘threshold’ for heat-related illness and death? 2.What are the types of heat hazards and temperature metrics that affect health? 3.How do we determine what is a heat-caused or heat- related death or illness? 4.Can we separate the epi heat signal from social vulnerabilities? 5.Are outdoor or indoor temperatures more related to health? 6.How might societal adaptations to climate change affect health outcomes? 10

11 Climate/Weather Consensus and Uncertainties 11

12 Temperature-mortality relative risk functions for 11 US cities, 1973–1994 Curriero F C et al. Am. J. Epidemiol. 2002;155:80-87 ©2002 by Oxford University Press Mortality rises steeply with temperature above a threshold 12

13 McMichael A J et al. Int. J. Epidemiol. 2008;37:1121-1131 International study of temperature, heat and urban mortality: the ‘ISOTHURM’ project 13

14 CLIMATE CHANGE and EXTREME HEAT EVENTS Possible displacement Steep rise, short delay 14

15 Threshold > = 97.5 th percentile above ‘normal’ 45°C (113°F) Range: 0-24 hours out of 4 days (96 hr) Mean: 12.65 Std Dev: 7.9 Hours of neighborhood exposure to threshold temperatures July 15-19, 2005 Ruddell et al. 2010. in Showalter and Lu (eds.) Geospatial Techniques in Urban Hazard and Disaster Analysis Weather Research Forecast model simulation 15

16 Summary: weather and climate uncertainties 1.Is high temperature or apparent temperature a better predictor of death? 2.Is maximum, mean, or minimum daily temperature a better predictor? 3.How much of a displacement effect do extreme heat events have on mortality? 4.Is there a cumulative effect of heat exposure on deaths? 5.Is everyone in a city exposed to the temperature that is being measured at the weather station(s)? Is more spatial resolution possible? 6.Could land surface temperature substitute for air temperature in order to get more spatial resolution? 7.Is it possible to generalize any of these answers or are they specific to city, neighborhood, person? 16

17 Heat-Related Health Consensus and Uncertainties 17

18 Temperature-mortality relationship for Maricopa County, AZ residents: 2000-2008 (May-October) Harlan et al. 2014. International Journal of Environmental Research and Public Health 11: 3304-3326. Direct exposure to environmental heat 10% days > 109 o 38% days > 104 o  Average daily deaths at AT max 34 C Cardiac disease/stroke 18

19 Harlan et al. 2014. International Journal of Environmental Research and Public Health 11: 3304-3326. Temperature – mortality thresholds and relative risk for males and females, under and over 65 year 19

20 Deaths are only the tip of the heat severity pyramid for health events Evidence that extreme temperature events (heat and cold) affect the use of medical services (including doctor services, ED services and hospital services) ED increasingly the primary source of acute care in U.S. and highly utilized by populations vulnerable to heat Maricopa County, AZ: Annualized heat-related ED visits are 4-fold higher than in-patient hospitalizations and hospitalizations are 10-fold higher than deaths. Hess et al. 2014. Environmental Health Perspectives DOI:10.1289/ehp.1306796 Petitti et al. in review 20

21 The 2006 California heat wave: impacts on hospitalizations and emergency department visits Knowlton et al. 2009. Environmental Health Perspectives 117: 61- 67. 21

22 Spatial composite heat vulnerability index scores in Atlanta, GA metro area Heat vulnerability variables: Heat exposure (2-day HI) Pct impervious surface Pct pop below poverty Pct pop elderly living alone Pct dialysis patients Pct hospital insufficiency 22

23 (by census block groups) Harlan et al. 2013. Environmental Health Perspectives 121: 197-204 Index Factors Socioeconomic Status Elderly / Living Alone Unvegetated Land Cover Heat vulnerability index scores and heat-associated deaths by census block groups in Phoenix metro area (2000-2008) 23

24 Mortality data collected from official U.S. death certificate Human decisions: potential cause of misclassification 24

25 Morbidity data collected from administrative claims (billing) records Dehydration HEAT ED Factors that Affect ED Use Severity of symptom Proximity of ED Income Age Insurance Etc., etc., etc. Home Admit Factors that Affect Hospital Admission Same 25

26 . Spatial indexes: social disadvantage or heat? “Our results suggest that the Heat Vulnerability Index may be a marker of health vulnerability in general, although it may indicate greater vulnerability to heat in some cases.” Colleen Reid “Compared with low-sensitivity groups, individuals living in neighborhoods with medium heat sensitivity are almost twice as likely to be hospitalized due to heat, while those in high sensitivity neighborhoods are almost four times as likely to be hospitalized. Two distinct sub-populations are found to be most sensitive to heat hazards: low-income, ethnic minorities in sparsely-vegetated urban core neighborhoods, and elderly people in retirement communities in the suburban fringe.” Juan Declet-Barreto Reid et al. 2012. Environmental Health Perspectives 120: 715-720 Declet-Barreto. 2013. Ph.D. Dissertation 26

27 Summary: health uncertainties In order to plan better intervention strategies, we want to know more about heat-health risks: 1.Are different types of illnesses/deaths associated with different types of hot weather/climates (temperature thresholds, exposure times, lags, etc.)? 2.Are effects of heat different for groups of susceptible people? Age, gender, and location-specific relationships are important to estimating impacts Very little to nothing is certain about ethnicity/race differences. 3.Do the models represent the data well enough? Are the anomalies in temperature/health outcome overlooked and unexplained? 4.Are more multi-city studies a priority or should researchers focus on individual cities? 5.Is indoor temperature more important than outdoor temperatures in determining health outcomes? (most people spend majority of time indoors, especially at night) 6.Can we disentangle and address the effects of heat vulnerability from other forms of social disadvantage? 27

28 The Future Consensus and Uncertainties in Projections Sherwood and Huber. 2010. PNAS 107:9552-9555 28

29 3 scenarios, 7 global climate models, ~ 166 – 2,217 excess annual heat wave deaths in Chicago, IL (2081-2100) Peng, RD et al. 2011. Environmental Health Perspectives 119: 701-706. 29

30 Projected annual net temperature-related deaths in Manhattan, NY 2 scenarios, 16 downscaled global climate models, seasonal temperature-related mortality Increase in heat deaths outweigh decrease in cold deaths The box symbols represent, from bottom to top, the minimum, 25th percentile, 50th percentile, 75th percentile and maximum across 16 models. Li, Horton & Kinney. 2013. Nature Climate Change 3: 717-721. 30

31 Adaptation = adjustments in socio-ecosystems systems to offset changes in climate systems Ebi et al. Outdoor Cooling Indoor Cooling Social Networks Social Institutions Illness and Death Temperature Poverty 31

32 CDC provides funding for state, territorial, and tribal health departments to conduct analytic and programmatic activities aimed at reducing the health consequences of climate change and variability by developing public health adaptation strategies using the BRACE framework. Piloting 16 states, 2 cities partner with scientists use models to predict, monitor, identify most vulnerable. Marinucci et al. 2014. Int. J. Environ. Res. Public Health 11, 6433-6458. itytoclimatechange.pdf BRACE: CDC framework for improving adaptive capacity of states and localities 32

33 Traditional Public Health and Safety Strategies 1.Identifying vulnerabilities - City works w/agencies to identify where elders live; Neighbors check on elderly via “buddy system” in heatwaves 2.Tracking - National Weather Service and excessive heat warning systems 3.Dept of Public Health, other agencies, and news media are in contact when heat wave is predicted, frequent public alerts; free “Heatline” 4. Public education – hot weather behavior 5. Activation of emergency measures - Cooling centers opened; no utility service suspensions; more Fire, EMS, Homeless service staff available Urban Planning and Remediation in Cities 5.Urban Heat Island Mitigation Program (EPA) - Trees and vegetation, cool roofs, cool pavement 6.Climate-Smart Design Cool Homes Program (EPA) encourages energy- efficient design; free energy audits 7.Federal Weatherization Assistance Program (DOE) for low-income households Local initiatives for adaptation to warmer cities 33

34 34

35 David Fink, Climate Resolve Los Angeles, EPA Webcast Keeping Your Cool: How Communities Across the Country are Reducing the Heat Island Effect, June 26 2014. 35

36 Heat deaths that occurred indoors in 2013 in Maricopa County, AZ – small sample, big problem 41% of heat-associated deaths in 2013 occurred indoors Air conditioning was installed in all but 1 case (3 unknown) Air conditioning was either not functioning, residence had no electricity, or AC was shut off 36

37 Barreca, A. et al. 2013. Adapting to Climate Change: The Remarkable Decline in the U.S. Temperature-Mortality Relationship over the 20 th Century, MIT Center for Energy and Environmental Policy Research. Decline of 80% in mortality effect of extremely hot days in the 20 th century Estimated reduction from 3,600 to 600 premature annual deaths due to hot days in second half of the century 37

38 Residential air conditioning explains almost entire decline in temperature-mortality Barreca, A. et al. 2013. Adapting to Climate Change: The Remarkable Decline in the U.S. Temperature-Mortality Relationship over the 20 th Century, MIT Center for Energy and Environmental Policy Research. 38

39 Apartment building with air conditioners in China (web) Can we repeat that? Potential demand for air conditioning in world’s 50 largest metropolitan areas AC in developing countries is rare but rising income is expected to increase demand. 38 of 50 largest metro areas are in developing countries. Energy implication: Potential annual cooling demand in Mumbai is 24% of demand for entire US (at current populations). Sivak M. 2009. Energy Policy 37: 1382-1384. 39

40 Quiz: A newspaper reporter calls you from the Arizona Daily Star in Tucson and says, “I received this press release about a new national study called Risky Business that was sponsored by some big foundations to assess the Economic Risks of Climate Change in the United States. I'm trying to find out if the forecasts in this report are realistic for Arizona. They say heat deaths in Arizona are going to increase by a large amount. The additional death figures seem high to me -- 14 to 43 additional deaths per 100,000 people. That compares to 139 heat-related deaths in 2013 in Arizona, which comes to a little more than two per 100,000 given the state's current population of something like 6.48 million. Can you comment on whether this is a credible estimate? 40

41 How do you respond? What are the uncertainties? “The report forecasts a seemingly modest increase of 2 to 6.4 percent in deaths related directly or indirectly to heat in various parts of Arizona by the end of the 21st century. But numerically, that amounts from 924 to more than 2,800 additional deaths in Arizona each year, assuming the current population. Last year, the Arizona Department of Health Services reported 139 deaths from heat induced illness. But that number typically includes only those linked to heat stroke and related symptoms caused directly by high temperatures, says Sharon Harlan, a senior sustainability scientist at Arizona State University’s Global Institute of Sustainability. The Risky Business estimates include all deaths directly or indirectly related to temperature — cardiovascular and respiratory diseases, and other underlying medical conditions. “There are many more deaths that are indirectly related to high temperatures than those caused by heat stroke,” she says. ASU’s Harlan says she believes the report is backed by high-quality research and should be taken seriously. The authors have thoroughly reviewed literature on temperature mortality relationships and selected the best national long-term studies to estimate deaths in individual states, she says.” 41

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