Tony McMichael

Colin Butler

National Centre for Epidemiology and Population Health

The Australian National University

Canberra

• Global health indicators have been improving - with some localand temporary exceptions

• World population size has been growing rapidly• So have aggregate economic activity and consumption levels• Simultaneously, many large-scale environmental and ecological

indices have been declining• Can we explain this apparent paradox?• What is the relationship of population health to sustainable

development?• Anticipatory versus empirical approaches: Is “evidence and

information” (the WHO orthodoxy) adequate for Big Policy?

Mortality Trends, Sweden, 1750-2000

Val

ue

Year

1750 1800 1850 1900 1950 2000

0

0.1

0.2

0.3

0.4

0.5

Male 5q0Female 5q0

Val

ue

Year

1750 1800 1850 1900 1950 2000

0

0.2

0.4

0.6

0.8

1

Male 45q15Female 45q15Probability, at birth,

of dying by age 5 yrsProbability, at age 15,of dying by age 60 yrs

Based on: Murray C, WHO, 2002

Males Females

Developing Countries, 1990s

Age-standardised death rate by socialclass (I-V), adult males, England and

Wales, 1911-1991

0

200

400

600

800

1,000

1,200

1,400

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Dea

ths

per

100

,000

Based on ONS UK:Based on ONS UK: Health Inequalities Health InequalitiesDecennial SupplementDecennial Supplement

I

IIIII

V

IV

Year

0

0.2

0.4

0.6

0.8

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

5q0Infant/child mortality

Adu

lt m

orta

lity

Based on: WHO, 2002

1% by 10%

0

20

40

60

80

100

1750 1800 1850 1900 1950 2000

Ind

ex o

f G

lob

al E

nvi

ron

men

tal

Ch

ang

e (%

)

Year Extension of earlieranalysis, of CD Butler

270

290

310

330

350

1966 1976 1986 1996

kgs

gra

in p

er c

apita

0

Time trend in global per-person production of cereal grain

2001

Three possible explanations:

• Modern societies, via technological, economic and politicalachievements, have become immune to environmental adversity.

• Adverse health effects are already occurring, but we cannot yetsee them.

• Lag period between environmental decline and health impacts.Lag reflects: (i) living off “capital”, (ii) buffering by culture.

Explanation 1 is untenable. Historically, the experience of manysocieties shows that, eventually, all are accountable within anecological sustainability calculus. A combination of explanations2 and 3 seems most plausible.

Human Population CarryingCapacity

• Non-human species: CC = f [natural capital]

• Humans: CC = f [NC, FC, BC, SC, HC]

– Inter-convertibility of types of capital

– Ability to expand HCC via culture/technology

– But: need to conserve the essential NC

• The environment sets limits on the size ofthe supportable local human population(given its particular level of “demands”).

• Societies find ways to extend that limit.

• Sustainable societies achieve a trade-offbetween supportable population size andsustainable environmental impact.

– Financial capital: international coffee price

– Social capital: resurgent tribal tensions

– Natural capital: shortage of arable land

�

Hunter-gatherer

Industrialising

Agrarian

Human CarryingCapacity

Population Demandon Environment

Globally “developed”

Will economic globalisation, and wealth creation, facilitate theHealth Transition – and help us achieve Sustainable Development?

Assumption: That the global “human carrying capacity” issufficiently elastic - to technology and greater wealth - to support,in future, a bigger and richer (higher consuming) population.

Probably erroneous!

Current modes of wealth creation are also eroding Earth’s life-supports, thus jeopardising the sustainability of current and futurehealth gains.

Tension between the Health Transitionand Sustainable Development

Consumptionpatterns

Technologies

Environmentalimpact

Wastes

Populationhealth status

Social capital

Knowledge

Recent Past Present Future

Population size, and distribution

Culture

Economic activityCarrying capacity:

critical thresholds

Healthgains

Healthlosses

?

• A change in human health/survival is responsive, notpredictive

• Further, this biological response is delayed by theinterposing of culture and technology – which expandsHCC, usually at the expense of natural capital.

• Deferral of ecological debt – e.g.:– Succession of ocean fisheries– Irrigation of drylands– Cyclone-proof housing

Trends in selected causes of death for womenaged 30-59 years in Russia 1965-1999

0

20

40

60

80

100

120

140

160

180

1965 1970 1975 1980 1985 1990 1995 2000

Year

SD

R p

er 1

0000

0

Accidents and violence

Ischaemic heart disease

Stomach cancer Breast cancer

Rheumatic heart disease

Shkolnikov & Leon

1950 1975 2000

Botswana

Uganda

SouthAfrica

35

45

55

65

75

Lifeexpectancy(yrs)

Year

• HCC has a prospective (“carrying”) dimension

• Can today’s population, with its current lifeexpectancy, and demands, be “carried”?– Global Years of Life Expectancy (GYLE) = Global

Population x Life Expectancy at birth

– i.e., current demand + committed demand on NC

• If so, can this demand be met without detriment tofuture generations?

0.1

10

1000

1750 1800 1850 1900 1950 2000

Population (billions)

GYLE (billions)

Global population and global years of lifeexpectancy (GYLE), 1750-2000

Year

Po

pu

lati

on

an

d G

YL

E (

bill

ion

s)(l

og

sca

le)

Po

pu

lati

on

an

d G

YL

E (

bill

ion

s)(l

og

sca

le)

Population (billions)

GYLE(billions)

Global population, global years of life expectancy(GYLE), and Index of Global Env Change (IGEC):

1750-2000

0.1

10

1000

1750 1800 1850 1900 1950 2000

IGEC (%)

Year

100

1

• Reduced rate of increase in life expectancy– But, alternative explanations

• Increased infant mortality (classical indicator)

• Resurgence of infectious diseases

• Reduced fertility (state- or family-initiated)

• Increased tension and conflict, relating toenvironmental assets (space, resources, food)

70

74

78

82

1964 1969 1974 1979 1984 1989 1994 1999

Gin

i co

effi

cien

t (%

)

Global income distribution (US$), 1964-1999

Butler CD, 2001

Inequality

Great wealth

Medium wealth

Poverty

NOW FUTURE

Environmental brinkmanshipbetween countries

(Resource extraction, trade patterns, wastes)

Arrested(?reversed)healthgains

Affluent consumption

Gains in lifeexpectancy

Gains in lifeexpectancy

Environmentaldamage

Poor health Health losses

Over-use oflocal naturalresources

Band of historical climatic variability

20

15

1900 21002000

14

16

17

18

13

19Average GlobalTemperature (OC)

Year205019501860

Low

High

Central estimate = 3.0 oC

IPCC (2001) estimatesa 1.4-5.8 oC increase

This presents a rate-of-change problem for manynatural systems/processes

0

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150

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1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25Temperature Increase

Ad

dit

ion

al m

illi

ons

of

peo

ple

at

ris

k o

f h

un

ge

r, m

ala

ria

an

d f

loo

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3500

1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25

Ad

dit

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al m

illi

ons

of

peo

ple

at

ris

k o

f in

cre

as

ed w

ate

r s

ho

rta

ge

Sta

bili

satio

n @

750

pp

mv

Un

miti

ga

ted

Sta

bili

sa

tion

@ 5

50

pp

mv

Risk of flooding

Risk of hunger

Risk of malaria

Risk of water shortage

Legend

Malaria

Water shortage

Hunger

Flooding

Temperature increase1 oC 2 oC 3 oC

Additional millions of people at risk of increased water shortage

Additionalmillions of people at risk of hunger, malariaand flood

150

250

Preliminary Estimates of Risk Functions for 4 Major Health-Related Consequences of Climate Change (DETR, UK, 20010 )

Estimates of Additional, Global, Numbers of People at Risk of 4Major Health-related Impacts of Climate Change by circa 2050-80

Based on a setof studiescommissionedby UK Govt.

Gains in health and longevity over the past century have followedurbanisation, social modernisation, industrialisation and increasingmaterial wealth, plus advances in public health and health care.

However, those health gains have depended, to an uncertain extent,on the depletion and degradation of the world’s naturalenvironment.

Theory, personal experience, and an increasing body of empiricaldata* suggest the existence of critical thresholds beyond which liedangers to society and risks to population health.

* Scheffer et al., 2001; Rauch, 2002

• Cause-effect lag times• Multiplicity of influences on population health• Uncertain determinants of the environment’s human carrying

capacity

Recent mortality/health trends, globally andregionally, actually cannot tell us if our socio-economic development path is “sustainable”.

Health outcomes are responsive, not predictive.

Further difficulties are:

We must therefore use an anticipatory approach.