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)

Negative Impact Positive Impact

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

Pathways for Weather to Affect Health: Example = Diarrheal Disease

TemperatureHumidityPrecipitation

Distal Causes Proximal Causes Infection Hazards Health Outcome

Living conditions(water supply andsanitation)

Food sources andhygiene practices

Survival/ replicationof pathogens in theenvironment

Contamination ofwater sources

Rate of personto person contact

Consumption ofcontaminated water

Consumption ofcontaminated food

Contact withinfected persons

Incidence of mortality andmorbidityattributableto diarrhea

Vulnerability(e.g., age andnutrition)

Contamination of food sources

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 300500 million infections, leading to approximately 13 million deaths

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 CO2 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, SO2, NOx, 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

Hayhoe et al. 2004

Scenario B1 A1fi

Heatwave days (Los Angeles) 4X 68X

Length of heatwave season

57 weeks

913 weeks

Heat-related mortality (Los Angeles) 23X 5–7X

Floods in 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

1992: 1,346 killed in Tajikistan1993: 125 died in Yekaterinburg, Russia1996: 86 died in the Biescas campsite, Spain1998: 147 died in Sarno, Italy2002: 120 died in Central Europe

Trends in Disasters over Time

1990 2020s

2050s 2080s

2050sKinney et al. 2006

Projected Changes in Ozone and Related Deaths, New York Metro Area

Climate Change Will Affect Flora and Fauna

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Temp Alberta Salmonella

meanlag1

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Temp Alberta Campylobacter

meanlag1

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Temp Alberta E. coli

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Temp Nfld-Lab Salmonella

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Temp Nfld-Lab Campylobacter

RR of Salmonella increased by 1.2% per degree above - 10˚C

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

Temperature and Enteric Disease

Distribution of Lyme Disease, 1991–2000 and 2020

00 1-461-46

47-9047-90

91-15991-159

160-266

160-266

267-433

267-433

434-694

434-694

695-1101

695-1101

1102-1738

1102-1738

1739-2145

1739-2145

Tick abundance at model equilibriumOgden et al., 2005, 2006a, 2006b

2020s

2050s

2080s

AB SK MB

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QC

LNF

PEINSNB

2020s

2050s

2080s

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PEINSNB

2020s

2050s

2080s

2020s

2050s

2080s

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Figure 3. Model-derived temperature limits for I. scapularis establishment in Canada mapped 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 for regions unaffected and affected by summer cooling by the Great Lakes. Standard errors in pale blue and brown lines for regions unaffected by summer cooling, and pink and red lines for areas affected by summer cooling. Broken red lines indicate projected geographic range of temperature conditions suitable for I. scapularis establishment in the 2020s, 2050s and 2080s using climate change projections (CGCM2 Scenario ‘A2’). Approximate locations of established I. scapularis populations are indicated by green triangles. (from Ogden et al., 2005a,c)

Modeled geographic limits projected for the establishment of I. scapularis ticks, in degree-days above 0ºC. 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).

Spread of Lyme Disease with Climate Change

Malaria in India

Bhattacharya et al. 2006

2050’s1980 to 2000

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