Climate Change and

HealthWith special reference to risks facing small island-

statesAnthony J McMichael

National Centre for Epidemiology & Population HealthThe Australian National University

Canberra, ACT 0200

Climate Change: the “debate”

Skepticism is now receding. We know that:• Greenhouse gas (GHG) concentrations are

increasing• GHGs affect the climate system (thankfully!)• World average temperature has risen relatively fast

over the past 30 years• Sea-level rise is gradually accelerating• Many temperature-sensitive systems/processes have

changed over the past two decades

Kilimanjaro 1970

Kilimanjaro 2000

Ice on Kilimanjaro

0

5

10

15

1900 1920 1940 1960 1980 2000 2020

Year

Are

a (k

m2 )

Climate Change: Basic Issues

• Earth’s climate varies naturally – because of a variety of cosmological and geological processes.

• “Climate change” refers to an additional, and relatively rapid, change induced by human actions.

• The additional change – several degrees C within a century – will disrupt the foundations of life on Earth.

• Ecosystems and life in general have evolved within a narrow band of climatic-environmental conditions.

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 Earths used by humanity

Based on Wackernagel et al, 2002

Nu

mb

er o

f E

arth

s

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

Band of historical climatic variability

20

15

1900 21002000

14

16

17

18

13

19Average Global Temperature (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-change problem for many natural systems/processes

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

200 400 600 800

Time from start (years)

0.0

0.5

1.0

1.5

Sea

-lev

el r

ise

(m) Total sea level rise

Ocean Expansion

Ice-melt

Greenhouse gas emissions (“super-Kyoto” action)

IPCC 2001IPCC, 2001

Sea-Level Rise, over the coming millennium

Peaking in 2050

SLR Risks to Small Island-States

• Coastal flooding• Amplified storm surges• Damaged coastal infrastructure (roads, etc.)• Salination of island fresh-water (esp.

subterranean cells)• Impaired crop production• Population displacement: diverse health

risks (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

Human exposures

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•Precipitation

Regional weatherchanges

•Heat waves•Extreme weather•Temperature•

•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 and demographic disruption

Effects of food and water shortages

Mental, nutritional,infectious-disease and other effects

Modulating influences

ENSO and climate change

• The effect of global climate change on the future frequency and/or amplitude of El Niño is uncertain .

• Events may become more frequent or more intense. • However, even with little change in amplitude,

climate change is likely to lead to greater extremes of drying and heavy rainfall, and to increase the risk of droughts and floods that occur with El Niño

[IPCC 2001].

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 2025Courtesy: Kris Ebi

Modelling Malaria Transmissibility in Zimbabwe. II

Baseline 2000 2025 2050Courtesy: Kris Ebi

Modelling Malaria Transmissibility in Zimbabwe. III

What Should Health Ministries Do?• Commission/conduct national assessments of risks to

health from CC (and SLR)• Participate in emergency management preparedness

(communications, facilities, skills) • Argue the centrality of population health as the real

“bottom line” in the sustainability debate• Make links with other ministries – education, primary

industry (agriculture), fisheries, development planning, etc.

• Highlight the sense and cost-savings of adaptation strategies, to lessen adverse impacts

ThatThat’s All’s All

Global average temperature (oC) over the past millennium

The International Energy Agency predicts that theincrease in greenhouse gas emissions from 2000 to 2030 in China alone will almost equal the increase from the entire industrialized world.

China is the world's second largest emitter of such gases, after the United States – even though China's per-person emissions are, for example, still only one-eighth of those in the United States.

GHG: Coming Decades

From: Steffen et al. 2003

Population Total real GDPForeign direct

investment

Damming of rivers Fertiliser consumption

Motor vehicles

Water use

MacDonalds Restaurants Urban population

International tourism

Climate change impacts on rain-fed cereal production, 2080

(IIASA: Fischer et al, 2001)

Need to convert estimates of regional food yields into estimates of changes in

numbers of malnourished people

Scenario: A1F1 (high) CSIROMK2

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Headland

Broome..

....

..Carnarvon.

Scenario: A1B (mid) CSIROMK2

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Headland

Broome..

....

..Carnarvon.

Darwin

Katherine

Cairns

Mackay

Rockhampton

Townsville

Port Headland

Broome..

..

....

Brisbane.Model Estimate: Current Dengue Risk Region

NCEPH/CSIRO/BoM, 2003

Dengue Fever: Estimated geographic region suitable for maintenance of Ae. aegypti, alternative climate scenarios for 2050

Categories of climate extremes

• Simple extremes based directly on climate statistics– Hot day = day with temperature > 95th

centile

• Complex, event-driven extremes– Droughts– Floods– Hurricanes/typhoons/tropical cyclones

Changes in climatic phenomenon

Confidence in observed changes

(latter half of 1900s)

Probability of projected

changes to 2100

Higher maximum temperatures - more hot days

Likely Very likely

Higher minimum temperatures, - fewer cold days and frost days

Very likely Very likely

Increase of heat index over land areas

Likely Very likely

More intense precipitation events Likely, (N mid to high

latitudes)

Very likely

Increased summer continental drying and associated risk of drought

Likely, in a few areas

Likely, over most mid-latitude continental interiors.

Increase in tropical cyclone peak wind intensities

Not observed in the few analysis

available

Likely, over some areas

Increase in tropical cyclone mean and peak precipitation intensities

Insufficient data Likely, over some areas

IPCC WORKING GROUP I, Third Assessment Report, 2001