Climate Change and
HealthWith special reference to risks facing small
island-states
Anthony 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