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Climate Change, Prolonged
Drought Conditions, and Health
Implications for Rural Australia
A.J McMichael
National Centre for
Epidemiology and Population Health
The Australian National University
Canberra
Outline of Presentation
• Global climate change: state of knowledge
• Implications for human health
• Climate change, drought conditions and
rural health . . . . . . .
• Need for coordinated research program,
including development of adaptive strategies
• Conclusion
Climate Change: Getting
the Science Right
Modelled projections of warming, for six
future greenhouse emissions scenarios
IPCC, Feb 2007: Wkg Gp I, Summary for Policy Makers
3 of the 6 GHG
emissions scenarios
Potential
error, to
one SD
Warming in ‘pipeline’ from
current GHG levels (~0.5oC)
A1F1
A2
1.8 - 4.0 oC
A1B
B1
1980-99 baseline
models
16-21 models
No. of
used for each
models
scenario
used
6 different GHG
emissions scenarios
Increased Weather Variability?
Canberra: Tues Feb 27, 2007
Climate Change: Faster
than Expected?
• IPCC 4 (2007) is somewhat conservative
 Limited to science published by late 2005
• Subsequent research* shows increasing
rates of:
 Global GHG emissions
 Temperature rise - especially in polar regions
 Ice melt
 Sea-level rise
* e.g. Rahmstorf, Church, et al., Science 2007
CC Impacts and Adaptation:
Relationships and Rationale
Applied
Research:
Primary Research
Response, Evaluation
Observed impacts
Predicted impacts
Prevent/slow
climate change
(mitigation)
Modify impacts
(adaptation)
Climate Change and Health: Pathways
1
Direct
impact
e.g. heatwaves,
floods, bushfires
Changes to physical
systems/processes
e.g. urban air pollution;
freshwater supply
Climate
change
2
Mediating
processes
(indirect)
Changes to biological
processes, timing
e.g. mosquito numbers, range;
photosynthesis, crop damage
 reduced food yields
Changes to
ecosystem structure
and function
e.g. fisheries; nutrient
cycles; forest productivity
3
Social,
economic,
demographic
disruptions
Health
impacts
(McMichael, 2005)
Sydney, Heatwave-related
Death Rates: Now and in 2100
For persons aged over 65:
• Now: 40 per 100,000
• 2100:
→ Low emissions scenario: 79/100,000
→ High emissions scenario: 239/100,000
450 ppm and SRES A2 scenarios:
CSIROMK2 & HADCM2
NCEPH/CSIRO, 2005
(ACF/AMA Report)
Dengue Fever: Estimated region suitable
for Ae. Aegypti mosquito, under alternative
climate-change scenarios for 2050
.
.
Darwin
Katherine
.
Darwin
.
.
Katherine
.
.
Broome
Port Headland
.
..
Current risk region for
dengue transmission
Townsville
Port Headland
Cairns
Townsville
.
Mackay
.
.
Cairns
Broome
.
Mackay
.
Risk region for medium Rockhampton
Carnarvon
emissions scenario, 2050
.
.
Rockhampton
.
.
.
Darwin
Brisbane
Katherine
.
Broome
.
Port Headland
.
.
Cairns
Townsville
.
.
Mackay
Rockhampton
Risk
region
for
high
Carnarvon
emissions scenario, 2050
.
NCEPH/CSIRO/BoM/UnivOtago, 2003
Australia’s Drought,
2001-2007
Trend in Mean Temperature,
1950-2005, Australia
Trend in Mean Temperature
1950-2005 (oC/10yrs)
Bureau of Meteorology (2006)
Trend in Annual Rainfall,
1950-2005, Australia
Trend in Annual Total Rainfall
1950-2005 (mm/10yrs)
Bureau of Meteorology (2006)
Rainfall in Dry Period: 2001-2006
Rainfall
Decile
Ranges
Highest on
record
Very much
> average
Above
average
Average
Below
average
Very much
< average
Lowest on
record
Sources of Rainfall
Variability
Known major causes
Approximate time scale
Weather patterns
Day/week
Southern Annular Mode
Weeks
Madden-Julian Oscillation
Month/s
Seasonal shifts in circulations Seasonal
El Niño (Southern Oscillation)
Inter-annual
Indian Ocean Dipole
Inter-annual
Inter-decadal Pacific
Oscillation
Inter-decadal
Drought: Related to
Climate Change?
• CC is causing a decline in winter rainfall
 Latitude (southwards) shift in rainfall system
• Higher temperature affects evaporation
– but complex relationship:
 Drier soils (?)
 Reduced capture/storage of water
• Higher sea-surface temp may cause
intensified El Niño events
Seasonal rainfall zones
And here?
Are the zones
being pushed
south, by
warming?
Summer dominant
Marked wet
summer and dry
winter
Winter
Wet winter and
low summer
rainfall
Summer
Wet summer
and low
winter rainfall
Winter dominant
Marked wet
winter and
dry summer
Uniform
Uniform
rainfall
Arid
Low rainfall
Drought: Recent expansion and likely
future expansion under climate change
Percentage of world’s land area in drought
50
Severe drought (5% circa 2000)
Extreme drought (1% circa 2000)
40
% in drought
30
20
10
0
1960
1980
2000
2020
2040
2060
2080
2100
Burke EJ, Brown SJ, Christidis N. 2006. Journal of Hydrometeorology
Climate Change: Impacts
on Rural Environment
• Climate conditions and food yields





Photosynthesis
Chills and frosts
Livestock health and growth
Extreme weather events: damage
Pests and diseases: plants and animals
• Invasive species: “weeds”
• Drought severity and duration
 Due to (?) shift in rainfall systems, evaporation, and
intensification of El Niño cycle
 Additional impacts because of reduced irrigation
Drought Conditions and
Long-Term Drying:
Risks to Health in Rural
Australia
NSW: Annual rainfall and
suicide rate, 1964-2001
Deaths per 100,000
Nicholls et al. Int J Biometeorol 2005
Low
Annual rainfall
High
Prolonged Drought Conditions:
Rural Health Risks
• Adult mental health problems
• Child emotional and material experiences:
impacts on development and health
• Exposures to extremes: heat, dusts, smoke
• Reduced freshwater supply: hygiene
• Local food production, prices: family diets,
nutrition and health
• Community erosion, income loss, low morale:
changes in health-related behaviours
• Remote indigenous communities: above, plus
loss of traditional plant/animal food species
• …. and benefits? (e.g. reduced mozzie numbers)
Outline of a Comprehensive
National Research Program
• Secondary (‘opportunistic’) analyses -from existing, large, population-based
epidemiological data sets
• Survey-research in selected rural
communities gathering information at
individual, family and community levels
• Develop/assess appropriate methods
and levels of intervention (‘adaptive
strategies’) -- to prevent or alleviate
adverse health impacts
The End
…The future will depend on the
nature of human aspirations,
values, preferences and choices…