Tony McMichaelNational Centre for Epidemiology and Population

HealthThe Australian National University

Global Climate Change: Health Risks – and

Preventive Strategies

Climate Change 101• The world’s climate is an integrated system

• Many factors (‘forcings’) influence the atmosphere’s uptake and distribution of energy (heat)

• Energy-trapping gases (esp CO2, water vapour, CH4) absorb outgoing re-radiated infrared radiation

– This raises Earth’s surface temperature

• Human activity is increasing the concentration of these ‘greenhouse’ gases

• CO2 concentration has increased from 275 ppm to 380 ppm over past century

– Current trend: 450 ppm by ~2030 (= + 2oC)

As humanity’s resource consumption increases, World Overshoot Day occurs earlier each year. The first Overshoot Day was Dec 19, 1987. Today, it is on October 9 – i.e., our Ecological Footprint is almost 30% larger than the planet’s biocapacity.  

World Overshoot Day = [World biocapacity / World Ecological Footprint ] x 365

This year, in just 282 days, we consume the biosphere’s entire capacity for 2006.

  www.footprintnetwork.org/gfn_subphp?content=overshoot

1987

2006

2000

October 9, 2006

Flo o d s

M a lar ia

D ia rr h oea

M a ln u tri tio n

02 04 06 08010 01 2 0 0 2 4 6 8 1 0

Deaths (thousands) DALYs (millions)

2000 2030

Estimated deaths and DALYs attributable to climate changeSelected health outcomes in developing countries

WHO, 2004: Global Burden of Disease

Now (2000)

Future (2030)

Total = 150,000 deaths/yr

Climate Change: Relevance to Med Students

• Professional– Advice to patients and families– Awareness of shifts in differential diagnosis– Contribution to organisational policy/advocacy– Participation in research– Health sector: energy efficiency, technology choices

• Citizen– Participation in public debate and political decisions– Community, family and personal decisions/behaviours

Doctors for the Environment

Australia

http://www.dea.org.au/

Poster Campaign 2005-2006

Recent Review Articles

McMichael AJ, Woodruff R, Hales S. Climate change and human health: present and future. Lancet, 2006; 367: 859-69.

Website of Intergovernmental Panel on Climate Change (IPCC) – Working Gp 2: chapter on Health Impacts (McMichael & Githeko)http://www.grida.no/climate/ipcc_tar/wg2/347.htm

Summary of Direction, Magnitude, and Certainty of Projected Health Impacts [IPCC: draft only]

Negative Impact Positive Impact

Very High Confidence

Effects on geographic range & incidence of malaria

High Confidence

Undernutrition & consequent disorders

Extreme events (heatwaves, storms, floods, droughts)

Illness/death due to (amplified) poor air quality

Cold-related deaths

Medium Confidence

Diarrhoeal diseases

Research at NCEPH

• Daily temperature + air pollution mortality & hospital admissions

• Weather patterns and asthma occurrence• Daily/weekly temp and food poisoning• Climatic and environmental influences on Ross

River Virus disease• Drought severity and mental health (suicides)• Modelling future changes in health risks w.r.t.

climate-change scenarios

Variations of the Earth’s surface temperature for the past 1,000 years: 1000-2000 AD

IPCC (2001): SPM 1b

Grey area shows statistical uncertainty range

2000

Past Climate Mean surface temperature, 1855-2004

Climate Research Unit, UEA, 2005

Temperature variation from 1961-90 average oC

Causes of Global Climate Change• Natural variability: wobbles of Earth’s axis and

changes in orbit (20K-100K yrs), solar activity, volcanoes, ENSO cycle

• Human activities: increases in greenhouse gases & aerosols, ozone depletion, land clearing

• IPCC: Most global warming since 1950 due to human activities (incr. greenhouse gas emissions)– Evidence for this:

• land-ocean temperature contrasts• annual cycle of terrestrial temperature• hemispheric temperature contrast• regional warming• height of tropopause (between troposphere/stratosphere) • pattern of ocean heating

Australia: Recent climate change [CSIRO]

• Warming of 0.9oC since 1910, mostly since 1950

• Minimum temperatures have risen twice as fast as maximum temperatures

• 2005 was Australia’s warmest year on record

• More heatwaves, fewer frosts

• More rain in north-west since 1950; less in south and east

Trend in mean temp, 1950-2005 (oC/10 yrs)

Annual total rainfall, 1950-2005 (mm/10 yrs)

Causes of climate change in Australia

• Warming since 1950 mostly due to global increases in greenhouse gases

• Rainfall trends: uncertain causes:– Increases in northwest: ? natural variability and

shift in weather patterns due to increases in northern hemisphere aerosols

– Decreases in south: ? natural variability plus greenhouse gas increases

– Decreases in east: ? increase in El Niño events since 1975 (uncertain cause)

131900 21002000

20

15

14

16

17

18

19Earth’s Average Surface Temp (OC)

Year205019501860

Central estimate:

2.5 oC increase

Band of 1200-yr historical climatic variability

Most of warming since 1950 is due to human actions (IPCC, 2001)

IPCC (2001) estimate:+ 1.4-5.8 oC by 2100

Climate Change ProjectionsInstead of simple extrapolation, CSIRO uses computer models of

the climate system, driven by future emissions scenarios for greenhouse gas and aerosols (and ozone depletion)

Emission scenarios (e.g. IPCC ‘SRES’) make assumptions about future demographic, economic & technology changes

Global CO2 Emissions Atmospheric CO2 Concentrations

Changes in Earth’s temperature over past 80 m years, and upper/lower estimates for next several centuries

Millions of years

2100

Barrett, Nature, 2003

Hundreds of years

Hominins appear

Now

Homo genus

PAST

FUTURE

Greenland Ice Sheet: Increase in Area Melted in Summer, from 1992 to 2002 (Arctic Climate Impact Assessment, 2004)

Orange area = melt-zone

1992 2002

Great Barrier Reef Annual bleaching by 2030-50 (CSIRO, 2006)

Two Important Perspectives

• Health risks are influenced by both ‘natural climate variability’ and by (human-induced) climate change

• Climate change typically acts in concert with other environmental changes

Worldwide Capture-Fisheries

Global fisheries harvest has declined since late ’80s

Global fisheries

Grand Banks cod fishery

Fish account for a high proportion of animal protein in the world’s diet – especially in many developing-country coastal communities.

Global marine fish harvest

25% of commercially exploited marine fish stocks are now seriously over-harvested (Millennium Ecosystem Assessment, 2005)

“… the distributions of both exploited and non-exploited North Sea fishes have responded markedly to recent increases in sea temperature…over 25 years. … Further temperature rises are likely to have profound impacts on commercial fisheries…”

Climate Change and Ocean Acidity Report by (UK) Royal Society, 30 June 2005

Increase in atmospheric carbon dioxide has significantly increased ocean acidity.

Report chairman: "Failure to cut CO2 emissions may mean that there is no place in the oceans of the future for many of the species and ecosystems that we know today.“

(Calcification – zooplankton, crustaceans, shellfish – is very sensitive to pH. These species are base of marine food web. )

That is, in combination:

• Over-fishing

• Ocean warming

• Ocean acidification

… are all impairing the food web and the future productivity of ocean fisheries

Illustrates problem of emerging global non-sustainability

Climate change

Social, economic, demographic disruptions

Biological changes: processes, timing

Changes to ecosystem structure and function

Direct impact

Mediating processes(indirect)

Health impacts

e.g. heatwaves, floods, fires

e.g. fisheries; constraints on microbes; nutrient cycles; forest productivity

Changes to physical systems/processes

e.g. urban air pollution

e.g. mosquito numbers,range; photosynthesis crop yields

Climate Change and Health: Pathways1

2

3

Three Types of Study

Past FuturePresent

Learn DetectEstimation, modelling

Empirical studies

Natural climate variation:- identify ‘effect’ - quantify risks

Current climate change:- detect effects- quantify effects- attribute burden

Future climate change:- estimate risks- est. attrib burden

Monthly cases of Salmonella food-poisoning in relation to monthly temperature

Australian cities, 1991-2001 (modelled best-fit graphs)

0

10

20

30

40

50

60

70

80

90

100

10 15 20 25 28

Temperature oC

Salmonella cases / month Perth

Brisbane

Adelaide

Melbourne

Sydney

D’Souza, Hall, et al., NCEPH/ANU, 2003

12-day Heatwave, 3-14 Aug, 2003

Maximum Temperature, Aug 10Excess Mortality:

France: 14,800

Italy: 10,000

Spain & Portugal: 5,000

Etc.

Total = 30,000+

Paris, Heatwave (Aug 2003): Daily Mean Temps and Deaths

30Mean daily temp, 2003

Mean daily temp 1999-2002

~12oC above season norm 25

15 oC

20

35 oC

~900 extra deaths during heatwave

350

300

250

200

150

100

0

Daily deaths

50

+8 oC

+12 oC

Based on: Vandentorren S, et al. AJPH 2004;94:1518-20.

Daily death rate

Average Warm Hot Extremely hot

We already have sufficient observations within this ‘normal’ temperature range

Daily temperature

?

c

b

a

Young adults

Old adults

Impact of Europe 2003 heat-wave suggests graph c, not b, applies at unusually hot

temperatures

Daily temperature and deaths: what happens at temperature extremes?

Tick-borne (viral) Encephalitis, Sweden: 1990s v 1980s (winter warming)Changing Distribution of the Tick Vector

Early 1980s

Mid-1990s

Lindgren et al., 2000, 2001

White dots indicate locations where ticks were reported. Black line indicates study region.

Baima lake Hongze lake

Freezing zone 1960-1990

Freezing zone 1970-2000

Schistosomiasis: Potential transmission of S japonicum in Jiangsu province due to raised avg January temperature. [Red lines = part of planned Sth-Nth water canal.]

Recent studies in China indicate that the increase in recorded incidence of schistosomiasis over the past decade may in part reflect recent warming. The “freeze line” limits survival of the intermediate host (Oncomelania water snails) and hence limits transmission of Schistosomiasis japonica. This parasite has moved northwards, putting 20.7 million extra people at risk (Yang, Vounatsou, et al. 2005).

Temperature change in China from 1960s to1990s

0.6-1.2 oC

1.2-1.8 oC

Yangtze River

Shanghai

Hurricane Katrina crossing Gulf of Mexico

Yellow/orange/red areas at or above 82°F (27.8°C) – the temperature needed for hurricanes to strengthen.

(NASA, 2005)

Estimating Future Influences of Climate Change on Health and

Health Risks

DroughtCSIRO estimates:• By 2030, drought frequency

increases by up to 20% over most of Australia

• By 2070, drought frequency increases by 20-80% in south, 20-40% in Qld, 0-20% elsewhere (except central WA)

CSIRO Mk2 model: 2030 (high)

% change in drought frequency

+80

+60

+40

+20

0

-20

-40

+80

+60

+40

+20

0

-20

-40

Mpelasoka et al. (in preparation)

Evidence of El Niño: 1997, 2006Sept 15 2006 Sept 20 1997

Sept 20 1997

Note: Warm surface equatorial waters are flowing east across the Pacific, brining rain to Central and South America coasts,

and leaving drought in Australia (and beyond)

TRANSMISSION POTENTIAL

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0.8

1

14 17 20 23 26 29 32 35 38 41

Temperature (°C)

Plasmodium Incubation period

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10

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50

15 20 25 30 35 40

(day

s)

Biting frequency

0

0.1

0.2

0.3

10 15 20 25 30 35 40

Temp (°C)(p

er d

ay)

Survival probability

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0.2

0.4

0.6

0.8

1

10 15 20 25 30 35 40

(per

day

)

Temp (°C) Temp (°C)

Malaria Transmissibility: Temperature and Biology

P.vivaxP.falciparum

Also: Pascual et al 2006

Baseline 2000 2025 2050

Ebi et al., 2005

Climate Change & Malaria (potential transmission) in Zimbabwe

Harare

Baseline 2000 2025 2050

Ebi et al., 2005

Climate Change & Malaria (potential transmission) in Zimbabwe

Baseline 2000 2025 2050

Ebi et al., 2005

Climate Change & Malaria (potential transmission) in Zimbabwe

Dengue Fever: Modelling of receptive geographic region for Ae. Aegyptii mosquito, under alternative

climate-change scenarios for 2050

Risk region for mediumemissions scenario, 2050

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome ..

....

..Carnarvon.

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome..

.

...

..

Brisbane.Current risk region for dengue transmission Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome..

..

..

..

Carnarvon. Risk region for high emissions scenario, 2050

NCEPH/CSIRO/BoM, 2003

Environmental Refugees UN projection (2006)

• By 2020: up to 50 million people escaping effects of environmental deterioration. – order-of-magnitude increase vs. 2005

• Inevitable spectrum of health risks – physical, nutritional, infectious, mental, and conflict situations

CO2 Stabilisation & Global Warming

0

1

2

3

4

5

6

1980 2000 2020 2040 2060 2080 2100

Year

Tem

pera

ture

ch

ang

e (o C

) SRES highSRES lowIPCC 450 ppm lowIPCC 450 ppm highIPCC 550 ppm lowIPCC 550 ppm high

1.21.41.5

2.3

2.9

5.8

Stabilising CO2 at:

550 ppm by 2150 could limit warming to 1.5-2.9°C by 2100.

450 ppm by 2090 could limit warming to 1.2-2.3°C by 2100.Note: Current level = 380 ppm (vs 275 pre-industrial)

Major Domains of Adaptation• Strengthening natural and infrastructural defences

against physical disasters– Institutional disaster preparedness

• Advance warning of epidemic outbreaks (Colombia, Indonesia, etc.)

• Managing water resources– Safety/quality and access– Mosquito breeding

• Reducing urban vulnerability– Protecting energy systems (decentralisation?)– Minimising heat islands

• Protecting food-producing systems and food access• Data systems: Monitoring, surveillance, analysis,

dissemination• Health-care system: structure, staffing, connectedness

Tasks for formal health sector1. Disease prevention

2. Public education

3. Disaster Preparedness

4. Early warning systems

5. Surveillance of disease occurrence and risk factors

6. Forecasting of likely future health risks

7. Engage in inter-sectoral discussions & policy devt

8. Minimise greenhouse gas emissions by health system infrastructure

- Resource-intensive hospitals: ~60% of public consumption

- Vic DHS: “HERO”; green hospitals

That’s all