Download Global Climate Change

Global Climate Change:
Health Risks – and
Preventive Strategies
Tony McMichael
National Centre for Epidemiology and Population Health
The Australian National University
Climate Change 101
• The world’s climate is an integrated system
• Many factors (‘forcings’) influence the atmosphere’s
uptake and distribution of energy (heat)
• Energy-trapping gases (esp CO2, water vapour, CH4)
absorb outgoing re-radiated infrared radiation
– This raises Earth’s surface temperature
• Human activity is increasing the concentration of
these ‘greenhouse’ gases
• CO2 concentration has increased from 275 ppm to
380 ppm over past century
– Current trend: 450 ppm by ~2030 (= + 2oC)
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
1987
2000
This year, in just 282 days, we
consume the biosphere’s entire
capacity for 2006.
2006
October 9, 2006
www.footprintnetwork.org/gfn_sub
php?content=overshoot
Estimated deaths and DALYs attributable to climate change
Selected health outcomes in developing countries
Floods
Malaria
Total =
150,000
deaths/yr
Now (2000)
Diarrhoea
Future (2030)
Malnutrition
120 100 80
60
40
20
Deaths (thousands)
0
2
4
6
8
DALYs (millions)
WHO, 2004: Global
Burden of
2000
2030
Disease
10
Climate Change: Relevance to
Med Students
• Professional
–
–
–
–
–
Advice to patients and families
Awareness of shifts in differential diagnosis
Contribution to organisational policy/advocacy
Participation in research
Health sector: energy efficiency, technology choices
• Citizen
– Participation in public debate and political decisions
– Community, family and personal decisions/behaviours
Doctors for the
Environment
Australia
http://www.dea.
org.au/
Poster Campaign
2005-2006
Recent Review Articles
McMichael AJ, Woodruff R, Hales S. Climate
change and human health: present and
future. Lancet, 2006; 367: 859-69.
Website of Intergovernmental Panel on
Climate Change (IPCC) – Working Gp 2:
chapter on Health Impacts (McMichael &
Githeko)
http://www.grida.no/climate/ipcc_tar/wg2/347.htm
Summary of Direction, Magnitude, and Certainty
of Projected Health Impacts [IPCC: draft only]
Negative Impact Positive Impact
Very High Confidence
Effects on geographic range & incidence of
malaria
High Confidence
Undernutrition & consequent disorders
Extreme events
(heatwaves, storms, floods, droughts)
Illness/death due to (amplified) poor air quality
Cold-related deaths
Medium Confidence
Diarrhoeal diseases
Research at NCEPH
• Daily temperature + air pollution  mortality &
hospital admissions
• Weather patterns and asthma occurrence
• Daily/weekly temp and food poisoning
• Climatic and environmental influences on Ross
River Virus disease
• Drought severity and mental health (suicides)
• Modelling future changes in health risks w.r.t.
climate-change scenarios
Variations of the Earth’s surface temperature
for the past 1,000 years: 1000-2000 AD
2000
Grey area shows
statistical
uncertainty range
IPCC (2001): SPM 1b
Past Climate
Mean surface temperature, 1855-2004
Temperature variation
from 1961-90 average oC
Climate Research Unit, UEA, 2005
Causes of Global Climate Change
• Natural variability: wobbles of Earth’s axis and
changes in orbit (20K-100K yrs), solar activity,
volcanoes, ENSO cycle
• Human activities: increases in greenhouse gases &
aerosols, ozone depletion, land clearing
• IPCC: Most global warming since 1950 due to
human activities (incr. greenhouse gas emissions)
– Evidence for this:
•
•
•
•
•
•
land-ocean temperature contrasts
annual cycle of terrestrial temperature
hemispheric temperature contrast
regional warming
height of tropopause (between troposphere/stratosphere)
pattern of ocean heating
Australia: Recent climate change
• Warming of 0.9oC since 1910,
mostly since 1950
• Minimum temperatures have
risen twice as fast as
maximum temperatures
Trend in mean temp,
1950-2005 (oC/10 yrs)
• 2005 was Australia’s warmest
year on record
• More heatwaves, fewer frosts
• More rain in north-west since
1950; less in south and east
Annual total rainfall,
1950-2005 (mm/10 yrs)
[CSIRO]
Causes of climate change
in Australia
• Warming since 1950 mostly due to global
increases in greenhouse gases
• Rainfall trends: uncertain causes:
– Increases in northwest: ? natural variability and
shift in weather patterns due to increases in
northern hemisphere aerosols
– Decreases in south: ? natural variability plus
greenhouse gas increases
– Decreases in east: ? increase in El Niño events
since 1975 (uncertain cause)
20
Earth’s
Average
19
Surface Temp (OC)
18
IPCC (2001)
estimate:
+ 1.4-5.8 oC by 2100
17
16
15
Most of warming since
1950 is due to human
actions (IPCC, 2001)
14
13
1860
Central
estimate:
2.5 oC
increase
Band of 1200-yr historical
climatic variability
1900
1950
2000
Year
2050
2100
Climate Change Projections
Instead of simple extrapolation, CSIRO uses computer models of
the climate system, driven by future emissions scenarios for
greenhouse gas and aerosols (and ozone depletion)
Emission scenarios (e.g. IPCC ‘SRES’) make assumptions about
future demographic, economic & technology changes
Global CO2 Emissions
Atmospheric CO2 Concentrations
Changes in Earth’s temperature over past 80 m years,
and upper/lower estimates for next several centuries
Hundreds
of years FUTURE
2100
Now
Homo genus
Hominins
appear
PAST
Millions
of years
Barrett, Nature, 2003
Greenland Ice Sheet: Increase in Area Melted in Summer,
from 1992 to 2002 (Arctic Climate Impact Assessment, 2004)
1992
Orange area = melt-zone
2002
Great Barrier Reef
Annual bleaching by 2030-50 (CSIRO, 2006)
Two Important Perspectives
• Health risks are influenced by both
‘natural climate variability’ and by
(human-induced) climate change
• Climate change typically acts in
concert with other environmental
changes
Worldwide Capture-Fisheries
Fish account for a high proportion of animal protein in the world’s diet –
especially in many developing-country coastal communities.
Global fisheries
25% of commercially exploited marine fish
stocks are now seriously over-harvested
(Millennium Ecosystem Assessment, 2005)
Grand Banks cod fishery
Global marine
fish harvest
Global fisheries harvest
has declined since late ’80s
“… the distributions of both exploited and nonexploited 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…”
Climate Change and Ocean Acidity
Report by (UK) Royal Society, 30 June 2005
Increase in atmospheric carbon dioxide has
significantly increased ocean acidity.
Report chairman: "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 – zooplankton, crustaceans, shellfish –
is very sensitive to pH. These species are base of
marine food web. )
That is, in combination:
• Over-fishing
• Ocean warming
• Ocean acidification
… are all impairing the food web and the
future productivity of ocean fisheries
Illustrates problem of emerging
global non-sustainability
Climate Change and Health: Pathways
1
Direct
impact
e.g. heatwaves,
floods, fires
Changes to physical
systems/processes
Climate
change
e.g. urban air pollution
2
Mediating
processes
(indirect)
Biological changes:
processes, timing
e.g. mosquito numbers,range;
photosynthesis  crop yields
Changes to
ecosystem structure
and function
e.g. fisheries; constraints on
microbes; nutrient cycles;
forest productivity
3
Social,
economic,
demographic
disruptions
Health
impacts
Three Types of Study
Empirical studies
Learn
Detect
Estimation,
modelling
Past
Present
Future
Natural climate
variation:
- identify ‘effect’
- quantify risks
Current climate
change:
- detect effects
- quantify effects
- attribute burden
Future climate
change:
- estimate risks
- est. attrib burden
Monthly cases of Salmonella food-poisoning in
relation to monthly temperature
Australian cities, 1991-2001 (modelled best-fit graphs)
100
Sydney
Melbourne
Brisbane
Perth
Adelaide
90
Salmonella
80
cases / month
70
60
50
40
30
20
10
0
10
15
20
25
Temperature oC
28
D’Souza, Hall, et al., NCEPH/ANU, 2003
12-day Heatwave, 3-14 Aug, 2003
Maximum Temperature, Aug 10
Excess
Mortality:
France:
14,800
Italy:
10,000
Spain &
Portugal:
5,000
Etc.
Total =
30,000+
Paris, Heatwave (Aug 2003): Daily Mean Temps and Deaths
35 oC
350
300
250
30
Mean daily
temp, 2003
200
150
Daily deaths
+12 oC
25
+8 oC
Mean daily
temp 1999-2002
~12oC above
season norm
20
15 oC
100
50
0
~900 extra deaths
during heatwave
Based on: Vandentorren S, et al. AJPH 2004;94:1518-20.
Daily temperature and deaths:
what happens at temperature extremes?
Impact of Europe 2003 heatwave suggests graph c, not
b, applies at unusually hot
temperatures
Daily
death
rate
We already have sufficient
observations within this
‘normal’ temperature range
c
b
?
a
Old adults
Young adults
Average
Warm
Hot
Daily temperature
Extremely hot
Tick-borne (viral) Encephalitis, Sweden: 1990s v 1980s (winter warming)
Changing Distribution of the Tick Vector
Early
1980s
Mid1990s
White dots indicate locations where ticks were reported. Black line indicates study region.
Lindgren et al., 2000, 2001
Schistosomiasis: Potential transmission of S japonicum in Jiangsu province
due to raised avg January temperature. [Red lines = part of planned Sth-Nth water canal.]
Freezing zone 1970-2000
Temperature change in
China from 1960s to1990s
0.6-1.2 oC
Freezing zone 1960-1990
Hongze lake
1.2-1.8 oC
Baima lake
Yangtze River
Recent studies in China indicate that the increase in recorded incidence
of schistosomiasis over the past decade may in part reflect recent
warming. The “freeze line” limits survival of the intermediate host
(Oncomelania water snails) and hence limits transmission of
Schistosomiasis japonica. This parasite has moved northwards, putting
20.7 million extra people at risk (Yang, Vounatsou, et al. 2005).
Shanghai
Hurricane Katrina crossing Gulf of Mexico
Yellow/orange/red areas at or above 82°F (27.8°C) –
the temperature needed for hurricanes to strengthen.
(NASA, 2005)
Estimating Future
Influences of Climate
Change on Health and
Health Risks
Drought
CSIRO estimates:
• By 2030, drought frequency
increases by up to 20% over
most of Australia
• By 2070, drought frequency
increases by 20-80% in
south, 20-40% in Qld, 0-20%
elsewhere (except central
WA)
CSIRO Mk2 model: 2030 (high)
% change in drought frequency
+80
+60
+40
+20
0
-20
-40
+80
+60
+40
+20
0
Mpelasoka et al. (in preparation)
-20
-40
Evidence of El Niño: 1997, 2006
Sept 15 2006
Sept 20 1997
Sept 20 1997
Note: Warm surface equatorial waters are flowing east across
the Pacific, brining rain to Central and South America coasts,
and leaving drought in Australia (and beyond)
Malaria Transmissibility: Temperature and Biology
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
0.6
0.4
0
10
Temp (°C)
0.8
0.2
10
0
Survival
probability
1
Biting frequency
Plasmodium
Incubation period
50
15
20
25
30
35
40
10
Temp (°C)
TRANSMISSION POTENTIAL
1
0.8
0.6
Also:
Pascual et al
2006
0.4
0.2
0
14 17 20 23 26 29 32 35 38 41
Temperature (°C)
15
20
25
30
Temp (°C)
35
40
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
Ebi et al., 2005
Dengue Fever: Modelling of receptive geographic
region for Ae. Aegyptii mosquito, under alternative
climate-change scenarios for 2050
.
.
Darwin
Katherine
.
.
.
.
Darwin
Katherine
Broome
.
.
.
.
.
Mackay
Townsville
.
Mackay
Current risk region for
dengue transmission
Townsville
Port Hedland
Cairns
Port Hedland
.
.
Cairns
Broome
.
.
.
Risk region for medium Rockhampton
Carnarvon
emissions scenario, 2050
Rockhampton
.
.
.
Darwin
Brisbane
Katherine
Broome
.
.
.
.
Cairns
Townsville
Port Hedland
.
.
Mackay
Rockhampton
Risk
region
for
high
Carnarvon
emissions scenario, 2050
.
NCEPH/CSIRO/BoM, 2003
Environmental Refugees
UN 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 –
physical, nutritional, infectious, mental,
and conflict situations
CO2 Stabilisation & Global Warming
o
Temperature change ( C)
6
5
4
3
5.8
SRES high
SRES low
IPCC 450 ppm low
IPCC 450 ppm high
IPCC 550 ppm low
IPCC 550 ppm high
2.9
2.3
2
1.5
1.4
1.2
1
0
1980
2000
2020
2040
2060
2080
2100
Year
Stabilising CO2 at:
550 ppm by 2150 could limit warming to 1.5-2.9°C by 2100.
450 ppm by 2090 could limit warming to 1.2-2.3°C by 2100.
Note: Current level = 380 ppm (vs 275 pre-industrial)
Major Domains of Adaptation
• Strengthening natural and infrastructural defences
against physical disasters
– Institutional disaster preparedness
• Advance warning of epidemic outbreaks (Colombia,
Indonesia, etc.)
• Managing water resources
– Safety/quality and access
– Mosquito breeding
• Reducing urban vulnerability
– Protecting energy systems (decentralisation?)
– Minimising heat islands
• Protecting food-producing systems and food access
• Data systems: Monitoring, surveillance, analysis,
dissemination
• Health-care system: structure, staffing, connectedness
Tasks for formal health sector
1. Disease prevention
2. Public education
3. Disaster Preparedness
4. Early warning systems
5. Surveillance of disease occurrence and risk factors
6. Forecasting of likely future health risks
7. Engage in inter-sectoral discussions & policy devt
8. Minimise greenhouse gas emissions by health
system infrastructure
- Resource-intensive hospitals: ~60% of public consumption
- Vic DHS: “HERO”; green hospitals
That’s
all