Protecting our Health from Climate Change: a Training Course for Public Health Professionals Chapter 4: Overview of the Health Impacts of Climate Change

Overview: This Module



Reviews the major health impacts of climate change, including increases in the frequency and intensity of extreme weather events (heatwaves, floods, windstorms, droughts); alterations in the transmission dynamics of food-, water-, and vectorborne diseases; and changes in the concentrations of air pollutants (including aeroallergens)

Health Impacts of Climate Change

McMichael et al. 2003a

Direction and Magnitude of Change of Selected Health Impacts of Climate Change (IPCC, 2007a) Very High Confidence

Malaria: Contraction and expansion, changes in transmission season

High Confidence

Increase in malnutrition Increase in the number of people suffering from deaths, disease and injuries from extreme weather events Increase in the frequency of cardio-respiratory diseases from changes in air quality Change in the range of infectious disease vectors Reduction of cold-related deaths

Medium Confidence

Increase in the burden of diarrheal diseases

Negative Impact Positive Impact

Pathways for Weather to Affect Health: Example = Diarrheal Disease Distal Causes Temperature Humidity Precipitation Living conditions (water supply and sanitation) Food sources and hygiene practices Proximal Causes Survival/ replication of pathogens in the environment Contamination of water sources Infection Hazards Consumption of contaminated water Consumption of contaminated food Contamination of food sources Contact with infected persons Rate of person to person contact Health Outcome Incidence of mortality and morbidity attributable to diarrhea Vulnerability (e.g., age and nutrition)

Multiple Factors Affect Climate Sensitive Health Outcomes

  

Biophysical factors

– – –

Baseline climate Elevation Natural resources (e.g., water bodies, soil moisture) Biological sensitivity

– – –

Concomitant diseases Acquired immunity Genetic factors Socioeconomic status

Intergovernmental Panel on Climate Change 4th Assessment

  

Health impacts due to climate change are occurring

–

Impacts unevenly distributed Impacts will increase with increasing climate change

–

All regions will be affected Mitigation and adaptation needed now

– –

Inertia in the climate system means change will continue for decades after successful control of greenhouse emissions Extent of health impacts over next few decades will depend on the design and implementation of effective adaptation measures

IPCC AR4 Health Impacts of Climate Change



Emerging evidence of climate change impacts:

–

Altered distribution of some vectors

– –

Altered seasonal distribution of some pollen species Increased risk of heatwave deaths

Annual Consequences of Diarrheal Diseases, Malaria, and Malnutrition in Children in Developing Countries

  

Diarrheal diseases cause nearly 2 million deaths, most attributable to contaminated water and inadequate sanitation and hygiene Malaria causes about 300 1



3 million deaths



500 million infections, leading to approximately Malnutrition is an underlying cause of approximately 50% of the 10.5 million deaths in children under the age of 5

Infant Mortality 1–4 Years

Worldmapper 2008f

World Population 1960

Worldmapper 2008e

World Population 2050

Worldmapper 2008b

Total CO 2 Emissions

UNEP 2009

Health Burden of Climate Change Impacts

Deaths from malaria and dengue fever, diarrhoea, malnutrition, flooding, and (in OECD countries) heatwaves

Greenhouse Gases and Air Pollutants

   

Most sources of greenhouse gas emissions also emit “conventional” air pollutants (PM, SO 2 , NO x , VOC), which have negative impacts on human health.

Many — but not all — GHG mitigation measures reduce also these air pollutants. Positive (side-)impacts on

–

Human health through reduced air pollution,

–

Air pollution emission control costs.

Some measures have important trade-offs.

Economic Co-Benefits of GHG Mitigation on Health

Findings of IPCC AR4



Health benefits make up between 50% and 400% of carbon mitigation costs



Benefits range from 7 $/t C (USA) to several 100 $/t C (China)

Climate Change Is about Children

And Other Vulnerable Groups

Sum of Years of Life Lost and Years of Life Lived with Disability

Pitcher et al. 2008

Impacts Will Depend on the Local Context

Philip Wijmans, LWF/ACT Mozambique, March 2000

Possible Impact Scenarios

    

Single large-scale disasters Repeated smaller disasters Continuous temperature increase producing gradual, linear increase in climate-sensitive health outcomes Any combination of the above Adverse health impacts of mitigation and adaptation measures

Climate Change Is Adding More Energy to the Atmosphere

http://earthobservatory.nasa.gov

Heatwave: August 2003 35,000 extra deaths over a two-week period

http://earthobservatory.nasa.gov

Emission Pathways, Climate Change, and Impacts on California

Scenario Heatwave days (Los Angeles) Length of heatwave season Heat-related mortality (Los Angeles) Hayhoe et al. 2004 B1 4X 5  7 weeks 2  3X A1fi 6  8X 9  13 weeks 5–7X

Floods in Europe

1992: 1,346 killed in Tajikistan 1993: 125 died in Yekaterinburg, Russia 1996: 86 died in the Biescas campsite, Spain 1998: 147 died in Sarno, Italy 2002: 120 died in Central Europe "EM-DAT: The OFDA/CRED International Disaster Database, www.em-dat.net – Université Catholique de Louvain – Brussels – Belgium." Created on: May-23-2005. Data version: v05.05

Trends in Disasters over Time

Projected Changes in Ozone and Related Deaths, New York Metro Area 1990 2020s 2080s 2050s

Kinney et al. 2006

2050s

Climate Change Will Affect Flora and Fauna

Temperature and Enteric Disease

Temp Alberta Salmonella Temp Alberta Campylobacter Temp Alberta E. coli -30 -20 -10 meanlag1 0 10 20 -30 -20 -10 meanlag1 0 10 20 Temp Nfld-Lab Salmonella Temp Nfld-Lab Campylobacter

RR of

Salmonella

increased by 1.2% per degree above 10˚C

-30 -20 -10 meanlag1 0 10 20

RR of Campylobacter

increased by 2.2% (4.5% in Newfoundland) per degree above 10˚C

RR of E. coli

increased by 6.0% per degree above 10˚C

Fleury et al. 2006 -20 -10 0 meanlag1 10 20 -20 -10 0 meanlag1 10 20

Distribution of Lyme Disease, 1991–2000 and 2020 Tick abundance at model equilibrium

Ogden et al., 2005, 2006a, 2006b

Figure 3. Model -derived temperature limits f or as limits in mean annual degree -days > 0°C . Estimated present day limits (using 1971 -2000 data) are indicated by dark blue and green lines respectively f or regions unaff ected and aff ected by summer cooling by the Great Lakes. Standard errors in pale blue and brow n lines f or regions unaff ected by summer cooling, and pink and red lines f or areas affected by

Spread of Lyme Disease with

conditions suitable for

I. scapularis

Climate Change

populations are indicated by green triangles. (f rom Ogden et al., 2005a,c)

Modeled geographic limits projected for the establishment of I. scapularis ticks, in degree-days above 0 ºC. Present modeled limits in blue or red (considering Great Lakes cooling effect). Triangles indicate endemic tick populations. Red dotted lines indicated projected change in the modeled geographic limits in three future time periods according to climate change scenarios (Ogden et al., 2005).

Malaria in India 1980 to 2000 2050’s

Bhattacharya et al. 2006

IPCC AR4 Health Impacts of Climate Change

 

Health co-benefits from reduced air pollution as a result of actions to reduce greenhouse gas emissions can be substantial and may offset a substantial fraction of mitigation costs Actions to reduce methane will decrease global concentrations of surface ozone

IPCC AR4 Health Impacts of Climate Change (cont.)

  

Adaptive capacity needs to be improved everywhere

–

Even high-income countries not prepared for extreme weather events Adverse impacts will be greatest in low-income countries

–

Those at greatest risk include the urban poor, the elderly and children, traditional societies, subsistence farmers, and coastal populations Economic development is important, but is insufficient to protect the world’s population against the health impacts of climate change

–

Critical factors include the manner in which growth occurs, the distribution of benefits, public health infrastructure, and other factors that determine population health

Epidemiologic Research Tasks

   

Exposure-response relationships between background climate variation and health outcomes Estimate the current health burden (e.g., annual deaths) attributable to climate change Develop scenario-based modeling to project health risks Assess health harms and benefits of proposed mitigation and adaptation policy options