Climate Change and its Impact on Health

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  • See also: Diarmid Campbell-Lendrum and Rosalie Woodruff 2006, “Comparative Risk Assessment of the Burden of Disease from Climate Change” Environ Health Perspect 114:1935–1941 DOI: doi:10.1289/ehp.8432
  • WHO has identified five major health consequences of climate change. 1. Malnutrition Rising temperatures and more frequent droughts and floods can compromise food security. Increases in malnutrition are expected to be especially severe in countries where large populations depend on rain-fed subsistence farming. 2. Deaths and injuries caused by storms and floods. In addition, flooding can be followed by outbreaks of diseases, such as cholera, especially when water and sanitation services are damaged or destroyed. Storms and floods are already among the most frequent and deadly forms of natural disasters. 3. Water scarcity / contamination Both scarcities of water, which is essential for hygiene, and excess water due to more frequent and torrential rainfall will increase the burden of diarrhoeal disease, which is spread through contaminated food and water. Diarrhoeal disease is already the second leading infectious cause of childhood mortality and accounts for a total of approximately 1.8 million deaths each year. 4. Heatwaves Heatwaves, especially in urban “heat islands”, can directly increase morbidity and mortality, mainly in elderly people with cardiovascular or respiratory disease. Apart from heatwaves, higher temperatures can increase ground-level ozone and hasten the onset of the pollen season, contributing to asthma attacks. 5. Vector-borne disease Changing temperatures and patterns of rainfall are expected to alter the geographical distribution of insect vectors that spread infectious diseases. Of these diseases, malaria and dengue are of greatest public health concern.
  • Chronic medical conditions (include pre-existing illnesses, e.g. cardiovascular, cerebrovascular and respiratory diseases, blood & metabolic/endocrine gland, cardio-pulmonary and genitourinary disorders) Service users/clients with special needs (Learning Disability, Physical Disability and Sensory Impairment, Older People, Mental Health & Substance Abuse)
  • Air quality: Main drivers of air pollution include emissions & meteorological conditions Although air pollution is thought to decline over the next 50 years, background concentrations of ozone are likely to increase, leading to at least 1500 extra deaths and hospital admissions Any decline in air quality could pose serious health problems for asthmatics. There is currently a public alert system advising the public according to the alert level reached Ozone levels in the UK are dependent on pollution control in Europe
  • Infectious diseases : Cases of food poisoning (salmonellosis, campylobacter) and water borne disease (cryptosporidiosis) linked to warm weather are likely to increase
  • Sunburn, skin cancer and cataract: Are likely to increase as people are going to sunbathe more/ greater sun & UV exposure because of the warmer weather.
  • River, Coastal Flooding & Flash Floods : The risk of major flooding disasters caused by severe winter gales, heavy rainfall and coastal erosion is likely to result in: Contamination of drinking water, Rise in waterborne infections Exposure to toxic pollutants, accompanied with Psychological consequences, disruption, injuries and deaths. Later effects of flooding include stress and mental health problems. River floods or storm surges, which can be forecast several days in advance, have fewer casualties compared to flash floods where there is no prior warning.
  • Rates of skin cancer are projected to show an upward trend in the coming years. It is difficult to know how much of this is related to global climatic change but it is not inconceivable that such change might make the upward trend even steeper. These are the England & Wales projections.
  • Possible ancillary health benefits : Such as increased physical activity due to extended warm weather.But, outcomes could be worse due to extreme heat. Reduced obesity and road traffic injuries through active transport Possibly healthy eating through adoption of sustainable farming & food policy and diets containing less animal products Reduced respiratory illness by improvements in air quality Increased home energy efficiency reducing temperature-related illness Possibly healthy eating if sustainable farming and food policy are adopted.


  • 1. Climate Change and its Impact on Health (JPCFM, Feb. 16, 2010) Ghaiath Hussein MBBS, MHSc. (Bioethics)
  • 2. Overview
      • Climate Change, Greenhouse Effect, and Global Warming Defined
      • Greenhouse gases
      • Evidence of global warming
      • Impact(s) of climate change
      • Impact on health
  • 3. Climate change
      • refers to any distinct change in measures of climate lasting for a long period of time, including major changes in temperature, rainfall, snow, or wind patterns lasting for decades or longer. Climate change may result from:
      • natural factors, such as changes in the Sun’s energy or slow changes in the Earth’s orbit around the Sun;
      • natural processes within the climate system (e.g., changes in ocean circulation);
      • human activities that change the atmosphere’s make-up (e.g, burning fossil fuels) and the land surface (e.g., cutting down forests, planting trees, building developments in cities and suburbs, etc.).
  • 4. Global warming
      • is an average increase in temperatures near the Earth’s surface and in the lowest layer of the atmosphere.
      • Increases in temperatures in our Earth’s atmosphere can contribute to changes in global climate patterns.
      • Global warming can be considered part of climate change along with changes in precipitation, sea level, etc.
  • 5. Greenhouse Effect
      • The greenhouse effect is a natural process that sees the Earth's atmosphere insulate the Earth. 
      • Incoming solar radiation (short-wave radiation) is absorbed at the Earth's surface.  The Earth's climatic system then redistributes this energy around the globe, through atmospheric and oceanic circulation patterns.  Energy is then radiated back from the Earth's surface into the atmosphere as long-wave radiation
      • Over time there is an approximate balance in this incoming (short-wave) and outgoing (long-wave) radiation.  Changes to this balance, such as changes in the amount of radiation received or lost by the system, or changes to the distribution cycles within the system, can affect climate.
  • 6.  
  • 7. Greenhouse gases
      • water vapor and carbon dioxide (CO2), occur naturally. human activities are adding large amounts of:
      • carbon dioxide, methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6).
      • Since 1750, atmospheric concentrations of CO2, CH4 and N2O have increased by over 36 percent, 148 percent and 18 percent, respectively. Scientists have concluded
  • 8.  
  • 9.  
  • 10. Global warmth…so what?
      • The heating of the Earth's surface and atmosphere affects these climate variables to produce extreme weather and climate events. 
      • Climate change is already being observed in a range of climate variables , such as: temperature, rainfall, atmospheric moisture, snow cover, land and sea ice, sea level, wind patterns and ocean circulation patterns. 
  • 11. Major global killers are affected by climate
    • Each year:
      • Weather– related disasters kill over 60,000
      • Undernutrition kills 3.5 million
      • Diarrhoea kills 2.2 million
      • Malaria kills 900,000
    • (WHO, 2003, 2008)
  • 12.  
  • 13. Global warming increases the likelihood it will be hot or very hot and decreases, but does not eliminate, the likelihood it will be cold or very cold. Source: IPCC, 2007
  • 14. Past and projected global average sea level. The gray shaded area shows the estimates of sea level change from 1800 to 1870 when measurements were not available. The red line is a reconstruction of sea level change measured by tide gauges with the surrounding shaded area depicting the uncertainty. The green line shows sea level change as measured by satellite. The purple shaded area represents the range of model projections for a medium growth emissions scenario (IPCC SRES A1B). For reference 100mm is about 4 inches. Source: IPCC, 2007
  • 15.  
  • 16. Agriculture and Forestry
      • The supply and cost of food may change as farmers and the food industry adapt to new climate patterns. A small amount of warming coupled with increasing CO2 may benefit certain crops, plants and forests, although the impacts of vegetation depend also on the availability of water and nutrients. For warming of more than a few degrees, the effects are expected to become increasingly negative, especially for vegetation near the warm end of its suitable range.
  • 17. Water Resources
      • In a warming climate, extreme events like floods and droughts are likely to become more frequent.
      • More frequent floods and droughts will affect water quality and availability.
      • increases in drought in some areas may increase the frequency of water shortages and lead to more restrictions on water usage.
      • An overall increase in precipitation may increase water availability in some regions, but also create greater flood potential.
  • 18. Energy
      • : Warmer temperatures may result in higher energy bills for air conditioning in summer, and lower bills for heating in winter. Energy usage is also connected to water needs. Energy is needed for irrigation, which will most likely increase due to climate change. Also, energy is generated by hydropower in some regions, which will also be impacted by changing precipitation patterns.
  • 19. Coasts
      • : If you live along the coast, your home may be impacted by sea level rise and an increase in storm intensity. Rising seas may contribute to enhanced coastal erosion, coastal flooding, loss of coastal wetlands, and increased risk of property loss from storm surges.
  • 20. Wildlife
      • Warmer temperatures and precipitation changes will likely affect the habitats and migratory patterns of many types of wildlife.
      • The range and distribution of many species will change, and some species that cannot move or adapt may face extinction.
  • 21.  
  • 22.  
  • 23. Anthroponotic Infections Zoonotic Infections Direct Exposure Indirect Exposure Environmental Exposures Vehicle Humans Source Stream pollutants Air Particulates Legionella Humans Humans STDs Measles Hepatitis B Vehicle Humans Humans Vehicle Malaria Dengue Roundworm Vehicle Vehicle Animals Animals Humans Lyme Disease Hantaviral Disease Most arboviral diseases Animals Animals Humans Anthrax Ebola (?) CJD Environment and Exposure Source Humans Solar UV EM Radiation Tetanus
  • 24. WHO: five major health impacts of climate change
      • Malnutrition
      • Deaths and injuries caused by storms and floods. (Flooding can also be followed by outbreaks of diseases, such as cholera)
      • Water scarcity / contamination (droughts and sudden floods) – increased burden of diarrhoeal disease.
      • Heatwaves – direct increases in morbidity and mortality; indirect effects via increases in ground-level ozone, contributing to asthma attacks.
      • Vector-borne disease – malaria and dengue.
  • 25. Vulnerable population groups
      • Chronic medical conditions including mentally ill, clients with special needs
      • Social isolation
      • Poor & vulnerable communities
      • Being confined to bed
      • Certain medical treatments
      • Some types of occupation, outdoor workers
      • Very young children
      • Elderly suffer the greatest effects of heat-waves (impact on mortality greater in women)
  • 26. Health impact of climate change
      • Air pollution - a reduction in the cold, calm winter weather associated with winter air pollution episodes together with reduced emissions of key pollutants including particles, oxides of nitrogen and sulphurdioxide could lead to a reduction (up to 50%) in the adverse health effects of winter air pollution.
      • A small overall increase in the number of summer ozone episodes coupled with a longer-term increase in background levels of ozone could cause a rise in the number of premature deaths.
  • 27. Air Pollution
      • Pollution determined by emissions & weather
      • Increases in ozone:
        • extra deaths &
        • hospital admissions
      • Air quality decline:
        • severity of asthma
      • Ozone levels dependent on pollution control in Europe
      • Between 2003 – 2020, increase in ozone levels will result in a 51-53% increase in attributable deaths and hospital admissions for respiratory diseases, threshold assumptions of 35-50ppb (attributable to climate change)
  • 28. Salmonellosis and temperature rise Modelled association between temperature and number of reported cases of salmonellosis in England and Wales (adjusted for outbreaks, seasonal factors and holidays) © S. Kovats (Data supplied by HPA)
  • 29. Infectious diseases – foodborne and waterborne diseases
    • Foodborne diseases
      • Likely increase in cases of food poisoning
      • incidence dependent on future food hygiene behaviour
      • evidence confirms the effect of temperature on salmonellosis
      • role of temperature in Campylobacter transmission remains uncertain
    • Waterborne diseases
      • Likely increase in cases of Cryptosporidiosis
      • Impact of increased temperature on water quality & disinfection
  • 30. Health impact of climate change
      • Extremes of temperature - heat-related deaths could increase to around 2,800 cases per year.
      • This is likely to be offset by milder winters leading to a fall in cold-related winter deaths of up to 20,000 cases per year.
  • 31.
    • Likely increases in:
      • Sunburn
      • Skin cancer
      • Possibly cataracts
    Exposure to ultra violet radiation
  • 32. Health impact of climate change
      • Flooding – increased frequency of severe coastal and river floods,
      • Analysis of more recent river flooding shows that mental health problems are the most important health impact among flood victims due to experience of personal and economic loss and stress.
  • 33. River, Coastal Flooding & Flash Floods
      • Few direct deaths
      • Full effect in terms of mortality and morbidity not known
        • Accidents – drowning, electrical
        • Contamination of drinking water
        • Rise in waterborne infections
        • Exposure to toxic pollutants
        • Psychological consequences
        • Disruption, injuries & deaths
        • Late effects include stress &
          • mental health problems
      • Food and water safety concerns
      • Effects on health and social service delivery
    UK floods of summer 2007
  • 34. Health impact of climate change
      • • UV exposure – levels of UV radiation reaching the earth’s surface may increase due to sunnier summers,
      • a decline in cloud cover and ozone depletion (which
      • reduces the capacity of the ozone layer to absorb UV).
      • predicted an extra 5,000 cases of skin cancer and 2,000 of cataract per year by 2050.
  • 35. Incidence of ‘All Skin Cancer’ England and Wales 1993-2002, and projections to 20251 Males, Females and all persons Directly aged standardised registration rates (DSR) Source: Health & Social Care Information Centre (2006). Compendium of Clinical & Health Indicators / Clinical & Health Outcomes Knowledge Base Note: International Classification of Disease and related health problems (ICD) definition of all skin cancers - ICD9 172-173, ICD10 C43-C44. Males Persons Females Year 1 Exponential projections based on data for the ten years 1993-2002
  • 36. Health impact of climate change
      • Vector-borne diseases – various diseases transmitted by mosquitoes or ticks are climate-sensitive and can increase or be introduced due to climate change.
      • Malaria might be re-established in non-endemic areas.
      • Potential emergence of other vector-borne diseases, such as West Nile Fever.
  • 37. Vector-borne diseases
      • Outbreaks of malaria likely to be rare
      • Tick borne likely to be more common, but relate to land use/leisure activities rather than climate change
        • Lyme disease – no observed correlation between temperature and incidence
        • Tick-borne encephalitis – low chances of occurrence
      • Possible increase in flies
    • (diarrhoeal disease), midges, fleas, stinging insects
      • Need to be alert to possibility of emerging infections
  • 38. Health impact of climate change
      • Food poisoning - higher temperatures in summer could cause an estimated 10,000 extra cases of salmonella infection per year.
      • Storms – any increase in the frequency of severe winter storms could lead to an increase in personal injuries from flying debris and falling trees.
  • 39. Health impact of climate change
      • Water-borne disease – climate change might increase levels of cryptosporidium and campylobacter in water.
      • Secure sanitation systems should safeguard supplies of drinking water, but possible contamination of stormwater outflows could carry disease into basements and nearby rivers, affecting the health of residents and river users.
  • 40. What diseases are the most climate sensitive?
      • heat stress
      • effects of storms
      • air pollution effects
      • asthma
      • vector-borne diseases
      • water-borne diseases
      • food-borne diseases
      • sexually-transmitted diseases
    High Low Sensitivity
  • 41. Health impact of extreme events
  • 42.
    • Lead to:
      • Social disruption
      • Homelessness
      • Injuries, deaths, disability
      • Impacts on food and water supply
    Extreme weather-related events (natural disasters)
  • 43. Health impact of extreme events
  • 44. Health impact of extreme events
  • 45.
    • Due to both direct & indirect effects:
      • Increased physical activity due to extended warm weather. But, outcomes could be worse due to extreme heat
      • Reduced obesity and road traffic injuries through active transport
      • Possibly healthy eating through adoption of sustainable farming & food policy and diets containing less animal products
      • Reduced respiratory illness by improvements in air quality
      • Increased home energy efficiency reducing temperature-related illness
    Potential health benefits
  • 46. Knowing is not enough; we must apply. Willing is not enough; we must do. (Goethe)
  • 47.
    • Discussion…
      • What diseases might have a climate link and what climate variables might impact on which diseases?
      • How would these be investigated/researched?
      • What additional information would you seek?
      • How would you integrate this into OTHER determinants of risk?
      • What other factors should be considered and why?
  • 48. Q & A