Climate Change, Environmental Change and Health:

Extending the Environment-Health Research and Policy Agenda

Tony McMichael

National Centre for Epidemiology and Population HealthThe Australian National University

Canberra

Environmental Health Risks Scale and Type

Acid rain (regional)

Global Climate-Environmental

changes

Direct, toxic, hazard

Disruption of life/health-support systems

Environmental tobacco smoke

Ambient air pollution

Environment & Health: Background

• Industrialization and urbanization continuation of ‘classic’ direct-acting environmental exposures: → chemicals, physical hazards and microbes (food/water)

• WHO: one-quarter of global disease burden (and one-third of burden in children) due to modifiable environmental factors (Pruss-Ustun & Corvalan, 2006)

→ main contributors: diarrhoea, lower respiratory infections, unintentional injuries, malaria

→ burden much higher in low-income than in high-income countries (25% of all deaths, versus 17%)

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MediumLow

Postnatal blood lead up to age 2 years

Gen. CognitiveIndex (McCarthy)IQ (WISC)

IQ (WISC)

2 yrs

11-13 yrs

7 yrs

4 yrsVariation in confounder-adjusted score(one pointapproximates to a one percent change in IQ)

Environmental Lead Exposure and Early Childhood Cognitive Development (McMichael et al)

5 IQ points per 20 ug/dl PbB

Age:

c. 5 ug/dl c. 25 ug/dlc. 15 ug/dlHigh

Motor DevtIndex (Bayley)

Globalisation

Mental hlth and psych disorders

Industrialisation Modernisation Future19001800 2000

Infectious diseases

Obesity

Urban air pollution

Road trauma

Greenhouse gas emissions climate change

Rise and Fall of Urban Health Penalties

Globalisation

Mental hlth and psych disorders

Industrialisation Modernisation Future

1900

1800 2000

Infectious diseases

Obesity

Urban air pollution

Road trauma

Greenhouse gas emissions climate change

Rise and Fall of Urban Health Penalties

Sanitation (infrastructure)

Food safety: laws/regs

Clean air laws

Road/car design

Seat-belt laws Drink/drive

laws

??? Displace responsibility to individuals

Delay, myopia, techo-optimism?

Garden City movementGerm Theory New Towns

WHO Healthy Cities

Education: domestic hygiene

Smoke control: Zoning, best-practice, etc.

Populations

Sub-groups

Individuals

1800 1850 1900 1950 2000

Esp. occupational groupings, industries

Epidemiology since ~1850: Changes in emphasis on different levels/units of analysis

Germ Theory,Micronutrients

Non-Infectious Dis:Esp. individual-level exposures, risk factors

Molecules and genes

Social epi

Sustaining population health: Understanding the effects of systemicchanges

Specific (measured) exposures

Urban v rural

Rich v poor

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 consumed the biosphere’s entire capacity for 2006.www.footprintnetwork.org/gfn_sub

php?content=overshoot

1987

2006

2000

October 9, 2006

Global Environmental Changes: Health Impacts, Social Responses

Global Environmental Changes, affecting:• Climate• Water• Food• Useful materials• Physical envtl. safety• Microbial patterns• Cultural assets• Aesthetics

Natural processes and forcings Impacts on human

society: • livelihoods• economic productivity• social stability• wellbeing• health

Mitigation: changes in social priorities, technology, culture

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2

3

Human society: • culture, institutions• economic activity• demography

Feedback change

Feedback change

Adaptation: risk management

Variations in Earth’s surface temperature for past 1,000 years: Northern hemisphere

IPCC (2001): SPM 1b

Grey area shows statistical uncertainty range

2000

131900 21002000

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15

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16

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19Earth’s Average Surface Temp (oC)

Year205019501860

Band of long-term historical climatic variability

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

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Changes in Earth’s temperature over past 80 million years, and upper/lower estimates for

next several centuries

Millions of years

2100Hundreds of years

Homininsappear

Homo genus

PAST

FUTURE

Barrett, Nature, 2003

Warmest IPCC scenario

Coolest IPCC scenario

Now

Greenland Ice Sheet: Increase in Area Melted in Summer, from 1992 to 2002

(Arctic Climate Impact Assessment, 2004)

Orange area = melt-zone

1992 2002

Climate change

Warming

Warming, plus rainfall changes, etc.

Glaciers meltingSea-ice recedingCoral reefs bleached/dying? More variable weather patterns

Birds, bugs and buds:Nesting timeMigration time/pathsBuds openingEtc.

Direct/indirect impacts on human biology and health

Many other factors

Difficulties with causal attribution

Simplepathways

Complexpathways

Climate Change Impacts on Natural Environment and Biological Systems

Rain Forest, with seasonal fruiting – bat diet

Forest clearing

Fruit orchards

Pig farming

Virus-contaminated fruit, bat droppings

Eaten by pigsInfected (sick) pigs

265 humans infected:JE-like illness~40% fatal~105 deaths

Nipah Virus Disease: Outbreak in Malaysian Pig Farmers, 1997-1999

El Niño drying

Forest-fire smoke (?)

i.e., ?? influencesDeforestation, El Niño conditions, Smoke haze:Decline in fruit

Fruit bats (with “their”virus: ~40% positive)

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

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

30Mean daily temp, 2003

Mean daily temp 1999-2002

~12 oC above season norm25

15 oC

20

35 oC

~900 extra deaths during heatwave

350

300

250

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150

100

0

Daily deaths

50

Kalkstein et al, in press

+8oC

+12oC

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?

Estimated deaths due to hot days

in 2100

Deaths due to hot days in

2000

Independent effect of ageing

Combined (additive) effect of

temperature+ ageing

Possible synergistic

effect of temperature

& ageing (esp. at higher temperatures

than previously encountered)

Independent effect of highertemperature

+ ???

+ 6,900

+ 600

+ 6,300

Baseline (current) no. of annual deaths due to heat = 1,100

+ 11,900

+ 14,000

+ 2,100

+ ???

Forecast heat-related deaths in people aged 65+, due to higher mean annual temperatures:

Australian capital cities, 2100

Woodruff et al. (2005) Climate Change Health Impacts by 2100

High GHG emissionsLow GHG emissions

‘Heat Island’ effect: Comparison of annual mean temperature in urban vs rural Shanghai

Tan Jianguo, 2005 (Beijing)

urban rural

Temperature (oC)

Urban

1.5 oC

Since mid-70s (as world has warmed by 0.5oC),

urban Shanghai has warmed by 2.5 oC,

versus 1.0 oC in rural

Rural

Food Systems: Yields, Access, Health

FAO data: ~840 million under-nourished personsAbsolute increase since 2000

• Over-worked soils (organic matter, etc.)• Chemicalisation (fertilisers)• Irrigation (water-logging, salination) • Climate change → temperature, soil moisture, monsoon systems, floods/droughts, etc.

• Ecosystem disruption (e.g. weeds, pollinators)• Mono-culture vulnerability to pests/infections• Livestock: pests/infections (CC and blue-tongue virus?)

• Access ‘(entitlement’) – social institutions, policies

Worldwide Capture-Fisheries

Global fisheries

Grand Banks cod fishery

Fish account for high proportion of animal protein in world diet –especially in developing-country coastal communities.

25% of commercial marine fish stocks now seriously over-harvested

(Millennium Assessment, 2005)

Global fisheries harvest has declined

since late ’80s

“… 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.”

Increase in atmospheric carbon dioxide has increased ocean acidity (pH 0.1 units).

Chair: “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 – in zooplankton, crustaceans, shellfish – is very sensitive to pH.These species are base of marine food web.

Climate Change and Ocean AcidityReport by (UK) Royal Society, June 2005

That is, in combination:

• Over-fishing• Ocean warming• Ocean acidification…all impair productivity of ocean fisheries

Illustrates well the (often) multi-causal nature of environmental non-sustainability

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 indicate that recent increase in recorded incidence of schistosomiasis may in part reflect warming. “Freeze line” limits survival of intermediate host (Oncomelania water snails), limiting transmission of Schistosomiasis japonica. Parasite has moved northwards, putting 20.7 million extra people at risk (Yang et al. 2005).

Temperature change in China from 1960s to1990s

0.6-1.2 oC

1.2-1.8 oC

Yangtze River

Shanghai

Risk Map (current) for Dengue: average of 100 bootstrap models

Green (prob < 0.5) = not suitable. Yellow Red = increasing suitability

For comparison: WHO map for dengue, 2003, is shown

with black linesRogers D, et al. Advances in Parasitology 2006

NCEPH/CSIRO/BoM, 2003

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 highemissions scenario, 2050

1990

2085

Estimated population at risk of Dengue Fever (i.e. vector climate envelope) under mid-range climate change scenario: 2085 (vs 1990)

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

TRANSMISSION POTENTIAL

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Temperature (°C)

Plasmodium Incubation period

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(day

s)

Biting frequency

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10 15 20 25 30 35 40Temp (°C)

(per

day

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Survival probability

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10 15 20 25 30 35 40

(per

day

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Temp (°C) Temp (°C)

Malaria Transmissibility: Temperature and Biology

P.vivaxP.falciparum

See also: Pascual et al 2006

Ebi et al., 2005

Climate Change & Malaria (potential transmission) in Zimbabwe

Baseline 2000 2025 2050

Harare

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

Baseline 2000 2025 2050

Environmental RefugeesUN 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 –infectious, nutritional, physical, mental, and conflict situations

Global warming: scenarios

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. Stabilising CO2 at 450 ppm by 2090 could limit warming to 1.2-2.3°C by 2100. Pre-industrial CO2 = 275 ppm; Current level = 385 ppm

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1980 2000 2020 2040 2060 2080 2100Year

Tem

pera

ture

cha

nge

(o C) IPCC (SRES) high

IPCC (SRES) lowIPCC 450 ppm lowIPCC 450 ppm highIPCC 550 ppm lowIPCC 550 ppm high

Now

Low-high range

Human pressures on environment

Impact on local envt:ContaminationResource depletion

Long-term impacts on human wellbeing, health and survival

The real reason for seekingSustainability

Near-term direct health impacts

Regional/Global environment:Disruption of natural systems

Impaired life-support processes(soil regeneration, climate stability; flood control; microbe constraints; nutrient cycling; etc.)

“Triple Bottom Line” – the focus of much current discussion

Reducedenvironmental assets: recreational, aesthetic, spiritual losses

Social disruption:jobs, institutions, etc.

Impaired economic productivity

Population Health as Key Criterion of Sustainability

…The future will depend on the nature of human aspirations, values, preferences and choices…The End

Health and Sustainability

Population health is both: • input to sustainable development, and• criterion (especially in the long term) for

the achievement of sustainability

i.e. Population health is the real bottom line (i.e., the purpose) of Sustainability

Tick-borne (viral) Encephalitis, Sweden: 1990s v 1980s (winter warming)Northward Trend in Distribution of Tick Vector

Early 1980s

Mid-1990s

Lindgren et al., 2000, 2001

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

Global Environmental Change & Health: causes, impacts, linkages

Immune suppressionEyes (cataracts, etc.)Skin damage/cancer

Land cover change

Direct impactsThermal stress: death, disease events, injuryStorms, cyclones, floods, firesSea-level rise: phys hazards, displacement

Changes in vector species (mosquitoes, etc.)

Infectious disease risks (emerging and resurging/spreading)

Food yields: nutrition and health

Predation by humans

Slums, hygiene; physical hazards; infectious disease risks (mobility, contact networks, density)

e.g. pollination

Avian ‘flu, Nipahvirus, BSE, etc.

Land use

Carbon cycle & Climate Change

Water systems, watersheds: management

Urbanisation; human settlements

Direct impactsStrat ozone depletion

(vulnerability)

Spread of invasive species

Food-production systems, methods (+ fisheries?)

Biodiversity changes

Climate change blamed for surge in Legionnaires' Disease

The Independent, UK, 18 October 2006

“Britain has suffered its first deaths from infectious disease attributable to global warming, official figures suggest.

“Cases of Legionnaires' disease, the bacterial lung infection which kills more than one in 10 of those it infects, reached record levels in August and September and experts say the extreme summer weather is the most likely cause of the rise.”

http://news.independent.co.uk/uk/health_medical/article1886640.ece

Monthly Salmonella food-poisoning cases in relation to monthly temperature

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

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10 15 20 25 28Temperature oC

Salmonella cases / month Perth

Brisbane

Adelaide

MelbourneSydney

D’Souza et al., NCEPH/ANU, 2003