Climate Change and Human Health: an overview

1. Climate Change and Human Health:an overview Sari Kovats Centre on Global Change and Health, Department of Public Health and Policy, London School of Hygiene and Tropical Medicine. 17 October 2005 RSS Meeting

2. International environment agenda • 1972 Club of Rome Limits to Growth . • 1972 UN World Conference on the Human Environment. • 1987. World Commission on Environment and Development “Our Common Future” • WSSD. [World Summit on Sustainable Development] Rio 1992 • Framework Conventions on Climate Change, Biodiversity and others. • Agenda 21 • 1997 Kyoto Protocol • WSSD - Johannesburg 2002 [Rio+10] • UN Kofi Annan proposed five key areas for particular focus: WEHAB [Water, Energy, Health, Agriculture, Biodiversity] • 2005 Kyoto Protocol comes into force. US opts out. • Millennium Development Goals

3. Shifting environmental burdens Local Global Immediate Delayed Risks to human health Risks to life support systems Smith et al. 1999

4. Source: WHO, 2003: Climate change and human health: risks and responses.

6. Past changes in global mean temperature

7. Global mean temperature.. future projections Source: IPCC, 2001

8. 1990 Reasons for concern 6 Several models - All SRES Envelope Observed A1F1 5 A1B A1T 4 A2 B1 3 B2 Temperature change (oC) IS92A 2 1 0 -1 1900 2000 2100 I II III IV V I Risks to Unique and Threatened Systems II Risks from Extreme Climate Events III Distribution of Impacts IV Aggregate Impacts V Risks from Future Large-Scale Discontinuities

9. IPCC WORKING GROUP I Third Assessment Report 2001

10. Climate change may entail change in variance, as well as a change in mean

11. Mortality in Paris during 2003 heat wave : 1999 - 2002 versus2003 Source: Institute de Vieille Sanitaire, France

12. approx 27,720 deaths

13. Impacts of climate change • Agriculture and food security • Sea level rise, coastal flooding and coastal areas. • Biodiversity and ecosystems • Water resources • Human health • Infrastructure, industry and human settlements • Weather disasters (floods, storms).

14. How climate change affects health Moderating influences HEALTH EFFECTS Heat-related illness, death Flood, storm-related health effects Air pollution effects Water- and food borne diseases Vector-borne and rodent-borne disease REGIONAL WEATHER CHANGES: - extreme weather - temperature - precipitation CLIMATE CHANGE Air pollution levels Contamination pathways Transmission dynamics Adaptation measures

15. three research tasks Empirical studies [epidemiology] predictive modelling learn ?analogues mechanisms responses detection attribution Future 2020s, 2050+ past present

16. Complexity: different types of evidence for health effects • Health impacts of individual extreme events (heat waves, floods, storms, droughts); • Spatial studies, where climate is an explanatory variable in the distribution of the disease or the disease vector • Temporal studies, • inter-annual climate variability, • short term (daily, weekly) changes (weather) • longer term (decadal) changes in the context of detecting early effects of climate change. • Experimental laboratory and field studies of vector, pathogen, or plant (allergenic) biology.

17. Assessment of causality… • measure and control confounders; • describe the geographical area from which the health data are derived; • use appropriate observed meteorological data for population of interest (the use of reanalysis data may give spurious results for studies of local effects); • have plausible biological explanation for association between weather parameters and disease outcome; • remove any trend and seasonal patterns when using time-series data prior to assessing relationships; • report associations both with and without adjustments for spatial or temporal autocorrelation.

18. Detection and attribution • What is the scientific evidence that global climate change is affecting human health? • Where and how should we be looking for evidence? • Considering the paucity of data, what do we accept as evidence within this context?

19. Tick-borne Encephalitis, Sweden: 1990s vs 1980s: winter warming trend Early1980s Mid-1990s White dots indicate locations where ticks were reported. Black line indicates study region. (Lindgren et al., 2000)

20. Evidence on biological effects of observed climate change • effects on physiology: metabolic or development rates of animals, and plant processes; • effects on distributions: response to shifts in mean temperature and precipitation conditions • Effect on phenology: timing of life-cycle events, e.g. budding of flowers or egg laying; • Adaptation: species with short generation times and rapid population growth rates may undergo some micro-evolution. Hughes 2000

21. Evidence of northward shifts: Europe • Bluetongue virus- disease and vector in Europe – (Mellor and Hamblin, 2004; Purse et al., 2005) • Leishmaniasis (which also affects humans) in dog reservoir • ? role of previous underreporting (Lindgren and Naucke, 2005) • Tick vectors- • Sweden (Lindgren and Talleklint, 2000; Lindgren and Gustafson, 2001) • Denmark (Skarphedinsson et al., 2005) • Canada (Barker and Lindsay, 2000)

22. How CC differs from other environmental health risk assessments • Scenario based. • Population not individual exposure assessment • Future worlds: • Population growth • Development pathway • disease baseline • relationship between climate and impacts (adaptive capacity)

23. Global Burden of Disease • Standard method developed by WHO. • Based on best-availablequantitative evidence • Estimates by region, age, sex • Combined metric – DALY • Disability adjusted life year • Identifies global and regional health priorities…

24. 2050 2100 Time 2020s 2050s 2080s Modelling impacts of climate change Greenhouse gas emissions scenarios Defined by IPCC Global climate scenarios: Generates series of maps of predicted future distribution of climate variables 30 year averages • Impact models • Estimates of populations at risk • hunger • water stress • coastal flooding • malaria • dengue 2020s 2050s 2080s

25. Assumptions: e.g. heat-related mortality • Adaptive capacity • Climate change concept, reflects ability of a population to cope with impacts of climate change • Acclimatization • Threshold of mortality response moves • Changes in exposure response relationship • E.g. due to changes in air conditioning access, etc. • Evident for both heat and cold effects • ?independent of aging population • Evidence base • Published studies that show observed changes since 1900….Heat (Davies, Keatinge) and cold (Kunst, Keatinge, Carson)

27. World Health Report 2002 Global Burden of Disease World Health Organization World Africa

28. Applying the relative risk to baseline incidence

29. Three eras of public health practice Source: Brown et al. 2005, p 5.

30. Conclusions • Estimates of near term impacts for health policy decision makers • Need scenarios of extremes • Downscaling • Interactions between cc and UHI [urban heat island] • Importance of population projections • Competing trends • Importance of metrics • Deaths, YLL, dollars. • Modifiers and adaptive capacity • Must be evidence based, but up to a point….