Health Impacts of Climate Change and Health
Conference: Public health benefits of strategies to reduce
greenhouse gas emissions
London School of Hygiene and Tropical Medicine
25 Nov 2009
A.J. McMichael
National Centre for Epidemiology and Population Health
The Australian National University
Canberra, Australia
Outline
1. Political context
2. Climate change: summary of recent science
3. Health Risks and Impacts
1. Research tasks; impact pathways
2. Examples: infectious disease, food yields/under-nutrition
4. Adaptation, Mitigation – and ‘Co-Benefits’
5. Conclusion
Climate and Health Council
Letter to Yvo de Boer, Exec Sec, UN Framework
Convention on Climate Change, Nov 10, 2009
“Whilst human-induced climate change looms as the
greatest threat to public health this century, the hopeful
health message is:
“What is good for the climate is good for health.
“There is ample evidence to support this.”
The Cassandra Effect
One who foresees, on available evidence,
a likely disaster; yet judges that this can’t
be prevented – and, that anyway, others
won’t believe the forecast.
• CC is counter-intuitive: How could
humans do that?
• ‘Climate’ vs. ‘weather’ confusion
• Cover-up of ignorance
• Influence of hired pens/lobbyists
• Resistance (esp. from ideological Right)
to calls for collective action and
government intervention. Spectre of
“world government”.
LSHTM as ‘epicentre’: Potted History
 1993-95: Health chapter, IPCC Second Assessment Report (1996)*: McMichael
(co-chair), Haines, Kovats, et al
 1996: WHO/UNEP book Climate Change and Human Health (eds: McMichael,
Haines, Slooff, Kovats)
 1999: McMichael AJ, Haines A (eds) Climate Change and Impacts on Human
Health. London: Royal Society
 1995-2000: LSHTM as international leader in CC/Hlth research; MRC (first)
Program Grant awarded, 2000 (LSHTM, Univ East Anglia)
 1998-2000: Health chapter, IPCC Third Assessment Report (2001)
•
2003-06: Health chapter, IPCC Fourth Assessment Report (2007)
 2001-2004: WHO contract: estimation of burden of disease attributable to CC
 2000s: Special reports with/for WHO – Vulnerability, Adaptation, etc.
 2008: UK Dept Health: Health Effects of Climate Change in UK: ed. Kovats
* no health chapter in IPCC First Assessment Report
Correlation between atmospheric carbon dioxide
concentration and Earth’s average surface temperature
14.5
390
370
350
CO2
ppm
14.3
Earth’s Temperature
(background wobble due
to natural influences)
CO2
concentration
330
310
14.1
13.9
Temp
oC
290
13.7
270
13.5
250
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
Year
Graph from: Hanno, 2009
Greenhouse Gas Concentrations and
Temperature Rise: Recent Science
• Global av temperature: clearcut (albeit naturally wobbly) uptrend
• Geophysical ‘fingerprints’ implicate increased GHG concentration as
main cause of 0.7oC rise since 1950
• Global climate models, now highly-coupled, perform well on record
of past ‘forcings’/temperature relationship – globally and regionally
• Six internationally-agreed plausible ‘human futures’ scenarios (i.e.
story-lines yielding GHG emissions at high, medium, low levels)
• Repeated runs with many models yield a range of best central
estimates for the 6 scenarios of 1.8-4.0oC, by 2100 [IPCC 2007]
• Range in projected temperature rise to 2030-40 mostly due to
residual uncertainties about climate system response to existing or
imminent atmospheric GHGs
• Uncertainties re warming in later decades mostly reflect unknowable
‘human futures’
Earth’s Temperature Chart, since
Dinosaur Extinction 65m yrs ago
Arctic ice
sheets
East Antarctic
West Antarctic
ice sheet
ice sheet
Paleocene
12
?
8
+5oC
4
0
Temp oC * (vs
+3oC
+1.5oC
last 2m yr
= ice-age
1961-90 av temp)
60myr
50myr
40myr
30myr
20myr
Millions of Years Before Present
* Temp measured
at deep ocean
10myr
Now
Sea level 25-40
metres higher
than today
Tripati et al Science 2009
Climate Change
occurring faster
than expected
IPCC’s Fourth Assessment Report (2007) now looks
conservative [in addition to cautious review process]
Subsequent research shows increasing rates of:
 Global Greenhouse Gas emissions
 Ice melting (Arctic sea ice, Greenland/Antarctic ice-sheets, alpine glaciers)
 Sea level rise
1m: half of Bangladesh rice fields
2m: most of Mekong Delta
Also:
 Increasing saturation of carbon ‘sinks’ (land and oceans)
 Estimated amount of carbon stored in permafrost
= twice the atmospheric carbon
Cyclone Ketsana,
Sept 2009
Approaching Vietnam
Hoi An,
Central Vietnam
Northern Cambodia
Rainfall estimates,
NOAA(USA), Sept 29
Climate Change and Health
Research Tasks and Policy Foci
Unintended
health effects
Natural
environmental
processes
Human pressure
on environment
Human society:
4
Adaptation: Reduce
health impacts/risks
3
Climate - environmental
changes, affecting:
Human impacts:
• Livelihoods
• Meteorological conditions
• Water flows
• Food yields
• Physical (protective) buffers
• Microbial activity
• Extreme weather events
• Population size
• Economic activity
• Culture, governance
• Social stability
1a-c
• Health
Health Cobenefits?
2
Mitigation of Climate
Change: Reduce
GHG emissions
Based on: McMichael et al., Brit med J, 2008
Need for local
prevention
Risks to
humans better
understood
Climate Change: Health Impact Pathways
Physical
systems
(river flows, soil
moisture, ocean temp)
Climate
Change
Impacts
Direct impacts
(extreme weather
events, heatwaves,
air pollutants, etc.)
Biological
cycles, in
nature … &
Ecological
links/function
Human Health:
•
•
•
•
•
•
Injuries/deaths
Thermal stress
Infectious diseases
Under-nutrition
Mental stresses
Other disorders
Economic/social
impacts: infrastructure,
farm/factory production, GDP
growth, jobs, displacement
Indirect
health
impacts –
ecologically
mediated
Indirect
health
impacts
– socially
mediated
Climate Change: Multiplier of
Conflicts and Regional Tensions
Regions afflicted by problems
due to environmental stresses:
• population pressure
• water shortage
• climate change affecting crops
• sea level rise
• pre-existing hunger
•
armed conflict, current/recent
From UK Ministry of Defence
[May RM, 2007 Lowy Institute Lecture. Sydney]
Deaths and DALYs attributable to Climate Change, 2000 & 2030
Selected conditions in developing countries
Deaths
Total Burden
Floods
Malaria
Now (2000)
Diarrhoea
Future (2030)
Malnutrition
120 100 80
60
40
20
Deaths (thousands)
0
2
4
6
8
10
DALYs (millions)
2000
2030
WHO/McMichael,Campbell-Lendrum, Kovats et al, 2004
Climate and Infectious Disease
• Climatic conditions set geographic and
seasonal limits of potential transmission.
• Other environmental, social and
behavioural factors – and public health
strategies – determine where/when
actual transmission occurs.
Model-fitted relationship of monthly Salmonellosis
case counts in relation to monthly av. temperature in
five Australian cities, 1991-2001
100
Sydney
Melbourne
Brisbane
Perth
Adelaide
Salmonella count
90
80
70
60
50
40
30
20
10
0
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Average MonthlyTemperature oC
D’Souza et al., 2003
Daily hospitalizations for diarrhoea, by daily
temperature: Lima, Peru.
(Shaded region is 1997-98 El Niño event)
Checkley et al, Lancet 2000
Daily Hospitalisations
Overall estimate from
regression analysis:
7% increase in daily cases
o C rise
per
1
Daily temperature
1993
1997
Estimated Mortality Impacts of Climate Change: Year 2000
Estimated annual deaths due to climate change: malnutrition
(~80K), diarrhoea (~50K), malaria (~20K), flooding (~3K)
14 WHO regions scaled according to estimated annual death rates
due to the change in climate since c.1970.
(Patz, Gibbs et al, 2007: based on McMichael, Campbell-Lendrum, Kovats, et al, 2004)
Bluetongue virus: Has
climate change caused a
northwards extension,
in Europe, of Culicoides
midge vectors?
2004: Northern range* of virus (in sheep)
2004: Northern limit C. imicola midge
1998: Northern range of virus (in sheep)
1998: Northern limit C. imicola midge
* Suggests additional
midge species are also
now contributing
Midge species: potential vectors of BT Virus
C. pulcaris
C. obselitus
C. imicola
Northern limit
Current northern limit
Southern limit
Northern limit < 1998
[“European” Midge species]
Source: Purse et al, 2005
Nature Reviews Microbiology
Schistosomiasis: Modelled Future Impact of Climate
Change on Schistosoma japonicum Transmission in China
Now
oC
2030:
+
0.9
Northwards drift, over past 4
decades, of the winter
‘freezing zone’ that limits
water-snail survival –
associated with 1-1.5oC
temperature
rise in SE China
o
2050: + 1.6 C
“Recent data suggest that
schistosomiasis is re-emerging in
some settings [with previous
successful disease control]. ….
“Along with other reasons,
climate change and ecologic
transformations have been
suggested as the underlying
causes.”
Source: Zhou et al., Potential Impact of Climate
Change on Schistosomiasis Transmission in China
Am J Trop Med Hyg 2008;78:188–194.
DENGUE FEVER: Estimated geographic region suitable
for A. aegypti vector, and hence transmission:
Climate conditions now and in alternative scenarios for 2050
Darwin
Darwin
.
Broome
.
.
.
Katherine
.
.
Katherine
.
..
.
Cairns
Townsville
Port Hedland
Townsville
.
2050 risk region: Medium GHG.
.
Port Hedland
Mackay
Rockhampton
.
emissions scenario
Carnarvon
Mackay
.
Current risk region, for
.
.
Cairns
Broome
Brisbane
Rockhampton
dengue transmission
.
.
Brisbane
Darwin
.
Katherine
.
.
Townsville
Port Hedland
Global statistical model (Hales), applied to
Australia: mosquito survival in relation to
water vapour pressure (rainfall, humidity).
.
.
Cairns
Broome
Mackay
2050 risk region: High GHG
Carnarvon
emissions scenario
.
.
.
Rockhampton
Brisbane
NCEPH/CSIRO/BoM/UnivOtago, 2003
Malaria Transmissibility: Temperature and Biology
Plasmodium
---------------- Mosquito -----------------Survival probability
Biting frequency
Incubation time
1
50
30
20
(per day)
0.3
P.vivax
P.falciparum
(per day)
(days)
40
0.2
0.1
0
15
20
25
30
35
40
0.4
0
10
Temp (°C)
0.6
0.2
10
0
0.8
15
20
25
30
35
40
10
Temp (°C)
15
20
25
30
35
Temp (°C)
TRANSMISSION POTENTIAL
1
0.8
0.6
0.4
0.2
0
14 17 20 23 26 29 32 35 38 41
Temperature (°C)
Based on Martens
WJM, 1998
40
Climate Change and Malaria
Potential transmission in Zimbabwe
Baseline 2000 2025 2050
Climate suitability:
red = high; blue/green = low
Harare
Low probability
Highlands
Medium probability
High probability
Bulawayo
Ebi et al., 2005
Climate Change and Malaria
Potential transmission in Zimbabwe
Baseline 2000 2025 2050
Climate suitability:
red = high; blue/green = low
Harare
Bulawayo
Ebi et al., 2005
Climate Change and Malaria
Potential transmission in Zimbabwe
Baseline 2000 2025 2050
Climate suitability:
red = high; blue/green = low
Harare
Bulawayo
Ebi et al., 2005
Food Yields: General Relationship
of Temperature and Photosynthesis
100%
Photosynthetic
activity
+2oC
+2oC
0%
20o C
Plus:
• Floods, storms, fires
• Droughts – range, severity
• Pests
o C
o C
30
40
• Diseases
Example: Field & Lobell. Environmental Research Letters, 2007:
Globally averaged: +0.5oC reduces crop yields by 3-5%.
So: +2oC would mean 12-20% fall in global grain production.
Modelled impact of climate change on
global cereal grain production:
Percent change, 1990-to-2080
% Change (range)
World
-0.6 to
-0.9
Developed countries
+2.7 to +9.0
Developing countries
-3.3 to
-7.2
Southeast Asia
-2.5 to -7.8
South Asia
-18.2 to -22.1
Sub-Saharan Africa -3.9 to -7.5
Latin America
+5.2 to +12.5
From: Tubiello & Fischer, 2007
Australia: Climate change, seasonal rainfall
zones, farm yields, health impacts
… and here?
Health
Consequences?
Are the zones
being pushed
south, by
warming?
Crucial for
wheat-belt
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
Avoiding the
Unmanageable
Mitigation and
Adaptation
Managing the
Unavoidable
‘Vulnerability’ and ‘Adaptation’
D Schroter et al, 2004
Vulnerability, Adaptation and Malaria Risk
External exposure:
climatic and
environmental conditions
Adaptive Capacity:
Local governance
Community cohesion
Funds available
Sensitivity of exposed population:
immune status, nutritional status,
housing conditions, etc.
Potential health impact risk of occurrence
of malaria
Public health capacity
Actual adaptive actions e.g.
Regional government
Meteorological forecasts
Community
Surface-water control
Mosquito spraying
Rapid case treatment
Household/personal
House repairs
Bed-nets
Net Vulnerability
to risk of malaria
Population
Health Impact:
actual outcome
Reducing Health Impacts of
Climate Change … Health CoBenefits as ‘bonus’
Disease
burden
Mitigation begins
emissions reduction (etc.)
Health impact
averted by mitigation
Impact avoidance
via adaptation
Baseline burden
now
Health Co-Benefits (local/regional)
2050
2100
Urgent Policy Tasks – to reduce:
• Atmospheric GHG concentrations
• Vulnerability of populations
• Pre-existing (amplifiable)
disease rates
Watch out on
Starboard !!
WAIT: We are in the
middle of a conference
on iceberg avoidance