Tony McMichael

National Centre for Epidemiology and PopulationHealth

The Australian National University

Global Environmental Changesand Human Health

Can We Detect, Measure and Controlthe Risks?

Proposition 1The great gains in population health overthe past 1-2 centuries have come fromsystemic changes in social and economicconditions, civic infrastructure, foodsupplies, education, and domesticmodernization.

Proposition 2As for animal herds, the healthprofile of a human communityreflects much about the conditions ofthe local environment and nature’s‘goods and services’.

Proposition 3Human pressures – a function ofpopulation size and economicactivities – are now changing variousof the planet’s regional and globallife-support systems (e.g. climate,biodiversity stocks, water supplies).

Challenge to populationhealth researchers

How to identify, attribute,quantify and reduce theresultant, often indirect, risksto human health.

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NB differentscale of y axis

1950-55 2000-05 1950-55 2000-05 1950-55 2000-05

Lif

e ex

pec

tan

cy a

t b

irth

, in

yea

rsTrends in life expectancy, 1950-now 3 categories: rising, flattening/plateauing, falling

From McMichael et al, Lancet, in press

Year

35 35

Hunter-gatherer

Industrialising

Agrarian

Human CarryingCapacity

Population Demandon Environment

“Over-developed”

1960s 1970s 1980s 1990s0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

One Earth is available(The planet’s total bio-capacity = 1.0)

Number of Earthsused by humanity

Based on Wackernagel et al, 2002

Num

ber

of E

arth

s

From: Steffen et al. 2003

Population Total real GDPForeign direct

investment

Damming of rivers Fertiliser consumption

Motor vehicles

Water use

MacDonalds Restaurants Urban population

From: Steffen et al. In press 2004

Atmos CO2 conc

Domesticated landLoss of trop forest, woodland

Coastal shrimp farmsFully exploited fisheries

Climate disastersAv surface temp (NH)Atmos ozone loss

Atmos CH4 concAtmos N2O conc

Coastal N2 flux

Global biodiversity

Changes in environmental indicators, 1750 - 2000

Climate Change: the “debate”Skepticism is now receding. We know that:

• GHG concentrations are increasing

• GHGs affect the climate system (thankfully!)

• World average temperature has risen relativelyfast over the past 30 years

• Sea-level rise is gradually accelerating

• Many temperature-sensitive systems/processeshave changed over the past two decades

Kilimanjaro 1970

Kilimanjaro 2000

Ice on Kilimanjaro

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10

15

1900 1920 1940 1960 1980 2000 2020

Year

Kilimanjaro 2020?

Are

a (k

m2 )

L.Thompson, in prep.

Source: Petit J.R., et al. Climate and atmospheric history of the past 420,000 years fromthe Vostok ice core, Antarctica. Nature 1999; 399: 429-436

10,000 yrsago: farmingbegins

Band of historical climatic variability

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15

1900 21002000

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16

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13

19Average GlobalTemperature (OC)

Year205019501860

IPCC (2001)estimatesa 1.4-5.8 oC increase

Low

High

Central estimate = 2.5 oC(plus increased variability)

This presents a rate-of-changeproblem for many naturalsystems/processes

GCM-Modelledincreases intemperatureunder the B2SRES Scenario

(UK Hadley CentreCM3 climatemodel)

2020s

2050s

2080s

GCM-Modelledchanges inprecipitationunder the B2SRES Scenario(UK Hadley CentreCM3 climatemodel)

2020s

2050s

2080s

Sea-level rise over coming centuriesfollowing 70 years of excess greenhouse gas emissions

200 400 600 800 Time from start (years)

0.0

0.5

1.0

1.5S

ea-l

evel

ris

e (m

) Total sea level rise

Ocean Expansion

Ice-melt

Greenhouse gas emissions

IPCC 2001IPCC, 2001

Sea-Level Rise, over the coming millennium

Peaking in 2050

Thank YouAn island of the Maldives, December 2003

Risks to Small Island-States

• Flooding

• Amplified storm surges

• Damaged coastal infrastructure (roads, etc.)

• Salination of island fresh-water

• Impaired crop production

• Population displacement: diverse healthrisks (nutrition, infection, mental health)

Health effects

Temperature-relatedillness and death

Extreme weather-related health effects

Air pollution-relatedhealth effects

Water and food-bornediseases

Vector borne and rodent borne diseases

Health Effects

Temperature-relatedillness and death

Extreme weather-related (floods, storms,etc.) health effects

Air pollution-relatedhealth effects

Humanexposures

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•Precipitation

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•Precipitation

•Sea-level rise

Contaminationpathways

Transmissiondynamics

----rodent

Microbial changes:

Contamination paths

Transmission dynamics

Water and food-bornediseases

Vector borne and borne diseases

Climate ChangeClimate Change

Changes in agro-ecosystems, hydrology

Socioeconomic anddemographic disruption

Effects of food andwater shortages

Mental, nutritional,infectious-disease andother effects

Modulatinginfluences

Daily temperatures and deaths in major Parisian hospitals, July-August 2003

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2 4 6 8 10 12 14 16 1825 27 29 31July August

Max daily temp

Min dailytemp

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Deaths Temp oC

(preliminary data from INVS, Paris)

Coexistentozone exposure?

Excess mortality, by department, in France during 1-15 August 2003, vs mean period-mortality in 2000-02

Excess mortalityUp to 25%25-49%50-74%75-100%> 100%

Heat wave, August 2003

• France >11,000 excess deaths• Portugal 1,316 excess deaths• Italy reports 20% more than average in July/Aug• Spain: 100 deaths reported• UK: 900 excess deaths reported

But- No standard method to estimate excess

Vulnerability in heat-waves

• Physiological• Pre-existing disease• Demographic

– Ageing population

• Social– Isolation– Housing quality

Climate change impacts on rain-fedcereal production, 2080

(IIASA: Fischer et al, 2001)

Need to convert estimates of regionalfood yields into estimates of changes in

numbers of malnourished people

What about the small island-states?

VECTOR-BORNE DISEASE

1990

2085

Estimated population at risk of dengue fever under“standard” climate change scenario: 1990, 2085

Source. Hales S et al. Lancet (online) 6 August 2002. http://image.thelancet.com/extras/01art11175web.pdf

Baseline 2000 Courtesy: Kris Ebi

Modelling Malaria Transmissibility in Zimbabwe. I

Baseline 2000 2025 Courtesy: Kris Ebi

Modelling Malaria Transmissibility in Zimbabwe. II

Baseline 2000 2025 2050Courtesy: Kris Ebi

Modelling Malaria Transmissibility in Zimbabwe. III

Prevention Options• Primary prevention

– Must cancel our collective ecological debt; live within thebiosphere’s limits

– Some radical choices needed, to achieve sustainability

• Adaptation (secondary prevention)– Too late to avert all adverse impacts; GEC processes are

prolonged and, sometimes, irreversible– Take action (preferably win-win action) to lessen adverse

impacts now and into the future

• IT MUST BE UNDERSTOOD THAT THE GOALSOF SUSTAINABILITY ARE TO DO WITH HUMANEXPERIENCE, NOT JUST WITH OUR CULTURALAND ECONOMIC ACCOUTREMENTS

The End